Utilization of Synthetic Near-Infrared Spectra via Generative Adversarial Network to Improve Wood Stiffness Prediction.

Near-infrared (NIR) spectroscopy is widely used as a nondestructive evaluation (NDE) tool for predicting wood properties. When deploying NIR models, one faces challenges in ensuring representative training data, which large datasets can mitigate but often at a significant cost. Machine learning and deep learning NIR models are at an even greater disadvantage because they typically require higher sample sizes for training. In this study, NIR spectra were collected to predict the modulus of elasticity (MOE) of southern pine lumber (training set = 573 samples, testing set = 145 samples). To account for the limited size of the training data, this study employed a generative adversarial network (GAN) to generate synthetic NIR spectra. The training dataset was fed into a GAN to generate 313, 573, and 1000 synthetic spectra. The original and enhanced datasets were used to train artificial neural networks (ANNs), convolutional neural networks (CNNs), and light gradient boosting machines (LGBMs) for MOE prediction. Overall, results showed that data augmentation using GAN improved the coefficient of determination (R2) by up to 7.02% and reduced the error of predictions by up to 4.29%. ANNs and CNNs benefited more from synthetic spectra than LGBMs, which only yielded slight improvement. All models showed optimal performance when 313 synthetic spectra were added to the original training data; further additions did not improve model performance because the quality of the datapoints generated by GAN beyond a certain threshold is poor, and one of the main reasons for this can be the size of the initial training data fed into the GAN. LGBMs showed superior performances than ANNs and CNNs on both the original and enhanced training datasets, which highlights the significance of selecting an appropriate machine learning or deep learning model for NIR spectral-data analysis. The results highlighted the positive impact of GAN on the predictive performance of models utilizing NIR spectroscopy as an NDE technique and monitoring tool for wood mechanical-property evaluation. Further studies should investigate the impact of the initial size of training data, the optimal number of generated synthetic spectra, and machine learning or deep learning models that could benefit more from data augmentation using GANs.

Genotype-dependent changes of cell wall composition influence physiological traits of a long and a non-long shelf-life tomato genotypes under distinct water regimes.

Water shortage strongly affects plants' physiological performance. Since tomato (Solanum lycopersicum) non-long shelf-life (nLSL) and long shelf-life (LSL) genotypes differently face water deprivation, we subjected a nLSL and a LSL genotype to four treatments: control (well watering), short-term water deficit stress at 40% field capacity (FC) (ST 40% FC), short-term water deficit stress at 30% FC (ST 30% FC), and short-term water deficit stress at 30% FC followed by recovery (ST 30% FC-Rec). Treatments promoted genotype-dependent elastic adjustments accompanied by distinct photosynthetic responses. While the nLSL genotype largely modified mesophyll conductance (gm ) across treatments, it was kept within a narrow range in the LSL genotype. However, similar gm values were achieved under ST 30% FC conditions. Particularly, modifications in the relative abundance of cell wall components and in sub-cellular anatomic parameters such as the chloroplast surface area exposed to intercellular air space per leaf area (Sc /S) and the cell wall thickness (Tcw ) regulated gm in the LSL genotype. Instead, only changes in foliar structure at the supra-cellular level influenced gm in the nLSL genotype. Even though further experiments testing a larger range of genotypes and treatments would be valuable to support our conclusions, we show that even genotypes of the same species can present different elastic, anatomical, and cell wall composition-mediated mechanisms to regulate gm when subjected to distinct water regimes.

Stress distribution and fracture resistance of green reprocessed polyetheretherketone (PEEK) single implant crown restorations compared to unreprocessed PEEK and Zirconia: an in-vitro study.

BACKGROUND: It is unclear which crown materials are optimum to disperse the generated stresses around dental implants. The objective of this study is to assess stress distribution and fracture resistance of green reprocessed Polyetheretherketone (PEEK) in comparison to un-reprocessed PEEK and zirconia single implant crown restorations. METHODS: Twenty crowns (n = 20) were obtained, five from zirconia and fifteen from pressed PEEK that were subdivided into 3 groups of five specimens each (n = 5) according to weight% of reprocessed material used. A 100% new PEEK was used for the first group, 50% new and 50% reprocessed PEEK were used for the second group, and a 100% reprocessed PEEK was used for the third group. Epoxy resin model with dental implant in the second mandibular premolar was constructed with strain gauges located mesially and distally to the implant to record strain while a load of 100 N was applied with 0.5 mm/min then specimens of all groups were vertically loaded till failure in a universal testing machine at cross head speed 1 mm/min. Data was statistically analyzed by using One-way Analysis of Variance (ANOVA) followed by Post-hoc test when ANOVA test is significant. RESULTS: No significant difference between strain values of tested groups (p = 0.174) was noticed. However, a significant difference between fracture resistance values was noticed where the zirconia group recorded a significantly higher value (p < 0.001). CONCLUSIONS: Implant restorative materials with different moduli of elasticity have similar effects regarding stresses distributed through dental implant and their surrounding bone. Reprocessed PEEK implant restorations transmit similar stresses to dental implant and surrounding bone as non-reprocessed PEEK and zirconia restorations. Zirconia failed at higher load values than all tested PEEK restorations but all can be safely used in the posterior area as crown restorations for single implants. CLINICAL RELEVANCE: Applying "green dentistry" principles may extend to include reprocessing of pressed PEEK restorative materials without affecting the material's shock absorption properties.

Comparison of Stress Distribution in Fixed Partial Prosthesis Restored with Different Combination of Support: A Finite Element Study.

AIM: This study was conducted to evaluate the distribution of stress in the bone around the natural tooth, endodontically treated tooth having post and core, and implant as an abutment in different combinations in fixed partial prosthesis using two-dimensional finite element analysis (FEA). MATERIALS AND METHODS: Six models were simulated using ANSYS Modeller19. All six models were divided into 12 zones and 4 lines, and stress values were calculated and compared. The study combinations were - tooth supported fixed partial prosthesis, fixed partial prosthesis having the combination of tooth and post- and core-treated tooth, fixed partial prosthesis with the combination of tooth and implant, fixed partial prosthesis having the combination of implant and post- and core-treated tooth, fixed partial prosthesis with the combination of post- and core-treated tooth on both sides, and fixed partial prosthesis having the combination of implant on both sides. RESULT: On comparing the stress values, the maximum stress value was observed in fixed partial prosthesis having the combination of implant on both sides (306.2434 MPa) followed by Model 4 (223.1255 MPa), Model 3 (154.3952 MPa), Model 5 (136.9041 MPa), Model 2 (116.2034 MPa), and least stress seen in Model 1 (99.6209 MPa), and minimum in tooth supported fixed partial prosthesis (99.6209 MPa). CONCLUSION: This study concluded that stress concentration in bone was maximum when the implant was used as an abutment in fixed partial prosthesis. The least stress was seen in bone around the natural tooth due to the dampening effect of the periodontal ligament. Further, the modulus of elasticity of a post acts as a vital parameter in the distribution of stress in post- and core-treated tooth. CLINICAL SIGNIFICANCE: The stress concentration in the bone around the abutments affects the longevity of the prosthesis, hence, the clinically appropriate combination of the abutments should be considered for a fixed partial prosthesis.

Linking water relations and hydraulics with photosynthesis.

For land plants, water is the principal governor of growth. Photosynthetic performance is highly dependent on the stable and suitable water status of leaves, which is balanced by the water transport capacity, the water loss rate as well as the water capacitance of the plant. This review discusses the links between leaf water status and photosynthesis, specifically focussing on the coordination of CO2 and water transport within leaves, and the potential role of leaf capacitance and elasticity on CO2 and water transport.

Xylem biomechanics, water storage, and density within roots and shoots of an angiosperm tree species.

Xylem is a complex tissue that forms the bulk of tree bodies and has several functions, including to conduct water, store water and nutrients, and biomechanically support the plant body. We examined how xylem functional traits varied at different positions within 9-year-old Populus balsamifera subsp. trichocarpa. Whole trees were excavated, and xylem samples were collected at 1-m increments along the main root-to-shoot axis of six trees, from root tip to shoot tip. We examined biomechanical and water-storage traits of the xylem, including using a non-invasive imaging technique to examine water content within long, intact branches (high-resolution computed tomography; microCT). Xylem density, strength, and stiffness were greater in shoots than roots. Along the main root-to-shoot axis, xylem strength and stiffness were greatest at shoot tips, and the tissue became linearly weaker and less stiff down the plant and through the root. Roots had greater water storage with lower biomechanical support, and shoots had biomechanically stronger and stiffer xylem with lower water storage. These findings support trade-offs among xylem functions between roots and shoots. Understanding how xylem functions differ throughout tree bodies is important in understanding whole-tree functioning and how terrestrial plants endure numerous environmental challenges over decades of growth.

Co-ordination between leaf biomechanical resistance and hydraulic safety across 30 sub-tropical woody species.

BACKGROUND AND AIMS: Leaf biomechanical resistance protects leaves from biotic and abiotic damage. Previous studies have revealed that enhancing leaf biomechanical resistance is costly for plant species and leads to an increase in leaf drought tolerance. We thus predicted that there is a functional correlation between leaf hydraulic safety and biomechanical characteristics. METHODS: We measured leaf morphological and anatomical traits, pressure-volume parameters, maximum leaf hydraulic conductance (Kleaf-max), leaf water potential at 50 % loss of hydraulic conductance (P50leaf), leaf hydraulic safety margin (SMleaf), and leaf force to tear (Ft) and punch (Fp) of 30 co-occurring woody species in a sub-tropical evergreen broadleaved forest. Linear regression analysis was performed to examine the relationships between biomechanical resistance and other leaf hydraulic traits. KEY RESULTS: We found that higher Ft and Fp values were significantly associated with a lower (more negative) P50leaf and a larger SMleaf, thereby confirming the correlation between leaf biomechanical resistance and hydraulic safety. However, leaf biomechanical resistance showed no correlation with Kleaf-max, although it was significantly and negatively correlated with leaf outside-xylem hydraulic conductance. In addition, we also found that there was a significant correlation between biomechanical resistance and the modulus of elasticity by excluding an outlier. CONCLUSIONS: The findings of this study reveal leaf biomechanical-hydraulic safety correlation in sub-tropical woody species.

Mitigation of waste rubber tire and waste wood ash by the production of rubberized low calcium waste wood ash based geopolymer concrete and influence of waste rubber fibre in setting properties and mechanical behavior.

World-class trend set was focusing on finding an alternative for cement which is a major pollutant to the environment by releasing greenhouse gas emission. Meanwhile, disposal of waste by generating a suitable method for its effective utilization is a major role of researchers in global. Geopolymer is one of the most suitable alternatives for the utilization of all industrial wastes with aluminosilicate source material in which has a disadvantage of requirement of high alkaline solution and exposed temperature curing. In this study, alternative for cement in the view of low calcium based geopolymer was introduced to reduce the aforementioned problem in GPC. Meanwhile, GPC has a problem on less brittle, less energy absorption and impact resistance. Rubber tire is a huge available waste material which is most harmful to the environment if it burnt. Waste rubber tire has a property of high elasticity and it has an abundant way to use in the concrete. In order to counteract the aforementioned problems, waste rubber as a fiber was added at a variation of 0.5, 1, 1.5 and 2% of volume fractions. The addition of fibre up to 1 percent improved the setting properties and mechanical behaviors in all ages of curing. At the age of 90 days, the compressive strength, split tensile strength, flexural strength and modulus of elasticity of low calcium geopolymer mix was increased by 4.36%, 6.25%, 3.64% and 10.62% respectively. Further, addition of waste rubber fibre beyond 1 percent results in decreasing of all strength parameters.

What drives photosynthesis during desiccation? Mosses and other outliers from the photosynthesis-elasticity trade-off.

In vascular plants, more rigid leaves have been linked to lower photosynthetic capacity, associated with low CO2 diffusion across the mesophyll, indirectly resulting in a trade-off between photosynthetic capacity (An) and bulk modulus of elasticity (ε). However, we evaluated mosses, liverworts, and Chara sp., plus some lycophytes and ferns, and found that they behaved as clear outliers of the An-ε relationship. Despite this finding, when vascular and non-vascular plants were plotted together, ε still linearly determined the cessation of net photosynthesis during desiccation both in species with stomata (either actively or hydro-passively regulated) and in species lacking stomata, and regardless of their leaf structure. The latter result challenges our current view of photosynthetic responses to desiccation and/or water stress. Structural features and hydric strategy are discussed as possible explanations for the deviation of these species from the An-ε trade-off, as well as for the general linear dependency between ε and the full cessation of An during desiccation.

Limited hydraulic adjustments drive the acclimation response of Pteridium aquilinum to variable light.

BACKGROUND AND AIMS: The success of invasive plants can be attributed to many traits including the ability to adapt to variable environmental conditions. Whether by adaptation, acclimation or phenotypic plasticity, these plants often increase their resource-use efficiency and, consequently, their fitness. The goal of this study was to examine the hydraulic and eco-physiological attributes of sun and shade populations of Pteridium aquilinum, a weedy fern, to determine whether the presence of vessels and other hydraulic attributes affects its success under a variety of light conditions. METHODS: Hydraulic traits such as cavitation resistance, hydraulic conductivity, photosynthesis and water potential at turgor loss point were measured on fronds from sun and shade populations. Anatomical and structural traits such as conduit diameter and length, stomatal density and vein density were also recorded. Diurnal measures of leaf water potential and stomatal conductance complement these data. KEY RESULTS: Gas exchange was nearly double in the sun plants, as was water-use efficiency, leaf-specific conductivity, and stomatal and vein density. This was largely achieved by a decrease in leaf area, coupled with higher xylem content. There was no significant difference in petiole cavitation resistance between the sun and shade leaves, nor in xylem-specific conductivity. Hydraulic conduit diameters were nearly equivalent in the two leaf types. CONCLUSIONS: Shifts in leaf area and xylem content allow P. aquilinum to occupy habitats with full sun, and to adjust its physiology accordingly. High rates of photosynthesis explain in part the success of this fern in disturbed habitats, although no change was observed in intrinsic xylem qualities such as cavitation resistance or conduit length. This suggests that P. aquilinum is constrained by its fundamental body plan, in contrast to seed plants, which show greater capacity for hydraulic adjustment.

Genetic Improvement of Sawn-Board Stiffness and Strength in Scots Pine (Pinus sylvestris L.).

Given an overall aim of improving Scots pine structural wood quality by selective tree breeding, we investigated the potential of non-destructive acoustic sensing tools to accurately predict wood stiffness (modulus of elasticity, MOE) and strength (modulus of rupture, MOR) of sawn boards. Non-destructive measurements of wood density (DEN), acoustic velocity (VEL) and MOE were carried out at different stages of wood processing chain (standing trees, felled logs and sawn boards), whilst destructively measured stiffness and strength served as benchmark traits. All acoustic based MOE and VEL estimates proved to be good proxies (rA > 0.65) for sawn-board stiffness while MOETREE, VELHIT and resistograph wood density (DENRES) measured on standing trees and MOELOG and VELFAK measured on felled logs well reflected board strength. Individual-tree narrow-sense heritability ( h i 2 ) for VEL, MOE and MOR were weak (0.05-0.26) but were substantially stronger for wood density (0.34-0.40). Moreover, additive genetic coefficients of variation for MOE and MOR were in the range from 5.4% to 9.1%, offering potential targets for exploitation by selective breeding. Consequently, selective breeding based on MOETREE, DENRES or stem straightness (STR) could improve several structural wood traits simultaneously.

Influence of thickness and aging on the mechanical properties of provisional resin materials.

This study aimed to evaluate the flexural strength (FS) and modulus of elasticity (ME) of 2 provisional resins at different thicknesses and after different storage periods. A total of 80 specimens were made of 2 provisional restorative materials (n = 40): Dencôr (DC) or Protemp 4 (PT). The specimens in each material group were prepared in 2 different thicknesses (n = 20): 1.5 mm or 2.0 mm. The groups were further subdivided by storage time (n = 10 per material thickness per time): 7 days or 3 months. A 3-point bending test was performed with a universal testing machine. Data were submitted to 3-way analysis of variance followed by a post hoc Tukey test (α = 0.05). Regarding the interaction of material and thickness, the 2.0-mm-thick DC specimens presented a significantly lower mean FS (41.08 MPa) than the other groups (P < 0.05). Regarding the interaction of material and storage time, PT after 3 months presented a significantly higher mean FS (75.51 MPa) than the other groups and periods (P < 0.05). Regardless of the material, the highest mean ME was found in the 1.5-mm-thick group after 3 months (2.24 GPa) (P < 0.05). The lowest ME values were found in the 2.0-mm-thick specimens after both storage times (7 days, 0.88 GPa; 3 months, 1.09 GPa), which were not significantly different from each other (P > 0.05). The correlation between FS and ME was direct and positive (R2 = 0.51; P < 0.001), independently of the variables (material, thickness, and time). Therefore, 2.0-mm-thick PT specimens presented the highest values of FS, mainly after 3 months. The ME was higher after 3 months (1.5-mm-thick specimens), regardless of the material. In addition, the higher the FS, the higher the ME of the material.

[Atomic force microscopy in the study of anterior eye segment structures]. / Atomno-silovaia mikroskopiia v issledovanii struktur perednego segmenta glaza.

The application of atomic force microscopy (AFM) in ophthalmology is considered with respect of the classical anatomical division of the eye into anterior and posterior segments. The review presents the findings of published research studies that involved AFM as a method for assessing anatomical and functional condition of the structures of anterior eye segment. One significant line of research is related to the use of AFM technologies for evaluation of morphological and biomechanical characteristics of various parts of the eye lens. That topic draws interest due to the need of furthering the understanding of cataractogenesis, as well as the significance of the anatomical and functional characteristics of the lens capsule in the mechanism of accommodation and modern phaco surgery.

Structural and biomechanical changes to dentin extracellular matrix following chemical removal of proteoglycans.

Proteoglycans are biomacromolecules with significant biomineralization and structural roles in the dentin extracellular matrix. This study comprehensively assessed the mechanical properties and morphology of the dentin extracellular matrix following chemical removal of proteoglycans to elucidate the structural roles of proteoglycans in dentin. Dentin extracellular matrix was prepared from extracted teeth after complete tissue demineralization. Chemical removal of proteoglycans was carried-out using guanidine hydrochloride for up to 10 days. The removal of proteoglycans was determined by dimethylmethylene blue colorimetric assay and histological staining analyses using transmission electron microscopy and optical microscopy. The modulus of elasticity of dentin matrix was determined by a 3-point bending test method. Partial removal of proteoglycans induced significant modifications to the dentin matrix, particularly to type I collagen. Removal of proteoglycans significantly decreased the modulus of elasticity of dentin extracellular matrix (p < 0.0001). In conclusion, the subtle disruption of proteoglycans induces pronounced changes to the collagen network packing and the bulk modulus of elasticity of dentin matrix.

Possible link between photosynthesis and leaf modulus of elasticity among vascular plants: a new player in leaf traits relationships?

A compromise between carbon assimilation and structure investment at the leaf level is broadly accepted, yet the relationship between net assimilation per area (An ) and leaf mass per area has been elusive. We propose bulk modulus of elasticity (ε) as a suitable parameter to reflect both leaf structure and function, and an inverse relationship between ε and An and mesophyll conductance (gm ) is postulated. Using data for An , gm and ε from previous studies and new measurements on a set of 20 species covering all major growth forms, a negative relationship between An or gm and ε was observed. High ε was also related to low leaf capacitance and higher diffusive limitations to photosynthesis. In conclusion, ε emerges as a key trait linked with photosynthetic capacity across vascular plants, and its relationship with gm suggests the existence of a common mechanistic basis, probably involving a key role of cell walls.

Do tall tree species have higher relative stiffness than shorter species?

PREMISE OF THE STUDY: In 1757 Leonhard Euler demonstrated that to avoid bending tall columns needed to be stiffer but not stronger than shorter columns of equal diameter and material density. Many researchers have concluded that trees have a fixed stiffness to basic density ratio, and therefore, trees adjust for increasing height by adding mass to adjust stem form. But the wood science literature points to considerable variance in stiffness with respect to green wood density. METHODS: Using the vast global repository of green wood mechanical properties, we compared relative stiffness and relative strength between taller and shorter species. For North American trees, we examined stem moisture distribution. KEY RESULTS: For all regions of the world, taller species on average possessed greater stiffness, but not strength, than shorter species of equal basic specific gravity. We looked for a possible universal mechanism that might allow taller tree species to adjust stiffness without affecting xylem specific gravity and concluded that the evidence points to a decrease in cellulose microfibril angle in structural cell walls combined with possible increases in holocellulose percentage. The evidence is strongest for conifers. We also showed that tall conifers have the ability to adjust the distribution of xylem moisture to maximize conduction while minimizing column load. CONCLUSIONS: Our research reveals that taller trees have developed internal stem adjustments to minimize diameter increase while attaining ever-greater heights, thus enabling these taller species to reduce energy expended on biomass accumulation while gaining greater access to solar radiation.

Non-Destructive Methodology to Determine Modulus of Elasticity in Static Bending of Quercus mongolica Using Near-Infrared Spectroscopy.

This article presents a non-destructive methodology to determine the modulus of elasticity (MOE) in static bending of wood through the use of near-infrared (NIR) spectroscopy. Wood specimens were obtained from Quercus mongolica growing in Northeast of China. The NIR spectra of specimens were acquired by using a one-chip NIR fiber optic spectrometer whose spectral range was 900~1900 nm. The raw spectra of specimens were pretreated by multiplication scatter correlation and Savitzky-Golay smoothing and differentiation filter. To reduce the dimensions of data and complexity of modeling, the synergy interval partial least squares and successive projections algorithm were applied to extract the characteristic wavelengths, which had closing relevance with the MOE of wood, and five characteristic wavelengths were selected from full 117 variables of a spectrum. Taking the characteristic wavelengths as input values, partial least square regression (PLSR) and the propagation neural network (BPNN) were implemented to establish calibration models. The predictive ability of the models was estimated by the coefficient of determination (rp) and the root mean square error of prediction (RMSEP) and in the prediction set. In comparison with the predicted results of the models, BPNN performed better results with the higher rp of 0.91 and lower RMSEP of 0.76. The results indicate that it is feasible to accurately determine the MOE of wood by using the NIR spectroscopy technique.

[The preliminary study on biomechanical properties of four synthetic implants for reconstructive surgery of pelvic floor dysfunction].

This study aimed to investigate biomechanical properties of synthetic implants for reconstructive surgery of pelvic floor dysfunction. In this dissertation, we chose four synthetic implants, i.e. total pelvic floor repair system (PROLIFT), gynecone TVT obtutator system (TVT-O), intra-vaginal sling placement device (IVS) and acellular dermal matrix (Renov), for tensile test respectively. The biomechanical properties of four synthetic implants were measured and analyzed using a material testing machine (Instron 4302 versatile material testing machine). The biomechanical parameters included ultimate stress strength, modulus of elasticity, maximum load and maximum elongation. The results showed that the maximum load of the four symthetic implants was TVT-O > IVS > PROLIFT > Renov, and the maximum load of TVT-O was significantly higher than PROLIFT and Renov ( P < 0.05). The ultimate stress strength was TVT-O > IVS > PROLIFT > Renov, with no significant differences among them ( P > 0.05). The maximum elongation of the four implants was TVT-O > PROLIFT > IVS > Renov, and the maximum elongation of TVT-O and PROLIFT were both significantly higher than Renov ( P < 0.05). The modulus of elasticity was IVS > Renov > TVT-O > PROLIFT, with no significant differences among them ( P > 0.05). Taken together, the present study demonstrates that the modulus of elasticity of IVS was the highest in the four synthetic implants; TVT-O had the highest mechanical strength; The maximum load, ultimate stress strength and maximum elongation of Renov were all the lowest; The mechanical properties of PROLIFT was the most stable, and its modulus of elasticity was the lowest in the four synthetic implants, which had good extensibility and elasticity. Therefore, it is necessary to pay attention to the biomechanical properties of new pelvic reconstructive materials for the clinical pelvic reconstructive surgery.

[The influence of hyperbaric oxygenation on the elastic properties of platelet membrane during spontaneous platelet aggregation in the patients presenting with cardiac co-morbidity]. / Vliianie giperbaricheskoi oksigenatsii na élasticheskie svoistva membrany trombotsitov pri ikh spontannoi agregatsii u patsientov s kardial'noi komorbidnost'iu.

BACKGROUND: The authors present evidence of the significance and role of the disturbances in platelet hemostasis in pathogenesis of co-morbid cardiac pathology and the absence of the unambiguous opinion as regards the expediency of the application of hyperbaric oxygenation (HBO) for their correction which implies the necessity of searching for new pathogenetically substantiated approaches to the treatment of the patients presenting with this condition. AIM: The objective of the present study was to evaluate the influence of hyperbaric oxygenation on the elastic properties of platelet membrane during spontaneous platelet aggregation in the patients presenting with cardiac co-morbidity. MATERIAL AND METHODS: Thrombocyte hemostasis was investigated in 24 patients at the age of 52.9±11.5 years (67% of men, 33% of women) presenting with functional class II angina of effort concomitant with arterial hypertension (AH). All the patients were given, in addition to the conventional treatment of the main diseases, the courses of daily (No. 5) 30-minute sessions of hyperbaric oxygenation in the 1,2ATA regime in the BLKS 301M and 303MK barochambers (Russia). Before and after HBO, spontaneous aggregation of thrombocytes (light agglomeration method) was determined with the use of a two-channel Biol LA-230-2 laser analyzer (Russia). The elastic properties of the platelet cell membrane were elucidated by atomic-force microscopy in the contact mode using the cantilever type PNP-DB on the Solver P47-PRO scanning probe microscope (Nt-MDT, Russia). RESULTS: The co-morbid cardiac pathology was accompanied by hyperaggregation and hypoaggregation of the platelets (33.3% and 25% respectively). The high levels of spontaneous aggregation in men (1.46±0.47) and the dependence of platelet plate stiffness on the aggregation state were documented. HBO sessions were accompanied by a reduction of spontaneous platelet aggregation in men (0.84±0.19) and a two-fold decrease in the modulus of elasticity in comparison with its initial value in the patients with platelet hyperaggregation (0.42±0.16, p<0.05). CONCLUSION: The membrane-modifying effect of HBO on the platelets is characterized by an increase in the elasticity of their membranes concurrent with a reduction of spontaneous aggregation of platelets, predominantly in men.

Cell wall swelling, fracture mode, and the mechanical properties of cherry fruit skins are closely related.

MAIN CONCLUSION: Cell wall swelling, fracture mode (along the middle lamellae vs. across cell walls), stiffness, and pressure at fracture of the sweet cherry fruit skin are closely related. Skin cracking is a common phenomenon in many crops bearing fleshy fruit. The objectives were to investigate relationships between the mode of fracture, the extent of cell wall swelling, and the mechanical properties of the fruit skin using sweet cherry (Prunus avium) as a model. Cracking was induced by incubating whole fruit in deionised water or by fracturing exocarp segments (ESs) in biaxial tensile tests. The fracture mode of epidermal cells was investigated by light microscopy. In biaxial tensile tests, the anticlinal cell walls of the ES fractured predominantly across the cell walls (rather than along) and showed no cell wall swelling. In contrast, fruit incubated in water fractured predominantly along the anticlinal epidermal cell walls and the cell walls were swollen. Swelling of cell walls also occurred when ESs were incubated in malic acid, in hypertonic solutions of sucrose, or in water. Compared to the untreated controls, these treatments resulted in more frequent fractures along the cell walls, lower pressures at fracture (p fracture), and lower moduli of elasticity (E, i.e., less stiff). Conversely, compared to the untreated controls, incubating the ES in CaCl2 and in high concentrations of ethanol resulted in thinner cell walls, in less frequent fractures along the cell walls, higher E and p fracture. Our study demonstrates that fracture mode, stiffness, and pressure at fracture are closely related to cell wall swelling. A number of other factors, including cultivar, ripening stage, turgor, CaCl2, and malic acid, exert their effects only indirectly, i.e., by affecting cell wall swelling.