Death and Taxus: the contribution of mechanical damage to the multiple factors associated with Taxus brevifolia mortality

In this paper, we investigate the effect of mechanical damage and temperature on copper indium gallium diselenide (CIGS) thin-film solar cells through experiments and modeling. After generating mechanical damage on CIGS solar cell with 20% increments, the electrical performance was measured (current-voltage curve) while temperature was varying from 10 to 70 °C at 20° increments. Other measured values are open-circuit voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> ), fill factor (ff), maximum power (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ). Those electrical values (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> , ff, P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ) are found as a function of temperature and percent damage. Moreover, the parameters of the single diode solar cell model were obtained as a function of temperature and percentage damage: light generation current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ), saturation current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ), shunt resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sh</sub> ), and series resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ). Our paper contributes to the deeper understanding of the concurrent effect of temperature and mechanical damage to solar cells.

Measurement of tropane alkaloid content in leaves ofAtropa acuminata after mechanical damage showed a maximum increase to 153% of the control 8 days later. There were no changes in the root or stem after similar damage. The plant responded to repeated mechanical damage by doubling its alkaloid content at 11 days after the initial wounding. But on further treatments, there was a slight decrease in alkaloid content with time. Mollusc feeding produced an increase of 164% in alkaloid content after 4 days. These results indicate that induced defence systems in angiosperms can vary considerably from plant species to plant species and that the effects of mechanical damage may differ in different parts of the same plant.

Moisture damage of hot-mix asphalt (HMA) pavement is an extremely complicated mode of distress. Previous researches on moisture damage mainly focused on the performances of undamaged pavement at the initial stage of opening to traffic. So with the permeability tests and the Hamburg Wheel Tracking Device (HWTD) tests, trial works were done to study the effect of traffic-load-induced mechanical damage on the evolution of moisture damage in HMA pavement. The monotonous uniaxial compression loading method and the repetitive compression loading method were employed to make the mechanical damages of the styrene–butadiene–styrene block copolymer-modified HMA specimens, respectively. Comparisons demonstrated that there were slight differences between the damages from the two kinds of damage making methods. The damages were characterised with two kinds of nondestructive testing methods (dynamic modulus testing method and ultrasonic wave testing method), and the relationship of the characterised damages with the two methods was obtained. The permeability tests of HMA showed that the coefficient of permeability initially decreases and then increases with the damage. HWTD test results implied that the mechanical damage had a significant influence on the moisture damage, especially in hot and humid environment. In HWTD test, the mechanical damage induced by the undesirable stress state in pavement accelerates the appearance of the striping inflection point and increases the cumulative deformation of HMA specimen. Therefore, in order to reflect the performance of asphalt pavement during its life cycle, the effect of mechanical damage on the evolution of moisture damage should be considered in pavement design and construction.

Rola zaburzeń w kształtowaniu struktury i dynamiki naturalnych lasów bukowo-jodłowo-świerkowych w Karpatach Zachodnich

In this work, the effect of mechanical damage on the thermal conductivity of granite was experimentally investigated. Granite samples were artificially damaged through cyclic loading and unloading tests, with the strain evolution and acoustic emission activity monitored simultaneously. P-Wave velocity of the damaged samples was tested to evaluate the damage effect. Thermal conductivity of the undamaged and damaged granite samples was tested using optical scanning method. The influence of mechanical damage on thermal conductivity was analyzed. Thermal conductivity difference in different testing directions was analyzed based on the experiment results in six scanning lines on the two surfaces of each disk sample. The results indicate that thermal conductivity of damaged samples reduced compared with that of the undamaged samples, while the thermal inhomogeneity factor increased. Thermal conductivity increased in water-saturated condition for both undamaged and damaged samples. The increased rate of damaged samples was bigger than that of the undamaged samples. The mechanical damage treatment caused the increase in the thermal conductivity difference in different testing directions. The difference decreased when samples were water saturated. Research results in this work can provide better knowledge to the evolution mechanism of thermal conductivity of engineering rock masses.

Coiled tubing (CT) is used in a rough and dynamic environment that renders it susceptible to mechanical damage on its outer surface. Such damage can adversely affect the fatigue life of CT by causing localized concentration of stresses and strains, or inducing microcracks from severe localized plastic deformation, that can lead to premature fatigue failure of the pipe. Failure statistics based on detailed failure examinations by BJ Services Company rank mechanical damage as the leading cause of CT failures accounting for 35% of all investigations. Repairs of the damaged pipe by welding or grinding are not always practical or even possible; therefore it is important to be able to estimate the remaining fatigue life of the damaged pipe so that the well servicing job can be completed with minimum risk of failure. Research efforts by the Coiled Tubing Mechanics Research Consortium at Tulsa University to determine the fatigue de-rating factors for damaged CT produced an algorithm ("Flexor TU4") that can predict the remaining fatigue life of the CT based on specific damage geometry, tubing characteristics and operating parameters. However, the majority of the testing for this algorithm has been conducted in air on artificial defects (i.e. machined) introduced on new and pre-fatigued tubing samples. Little previous research has been conducted to compare "Flexor TU4" predictions with the remaining fatigue life measured on CT with real defects (i.e. damage caused during service). Also, the effect of mechanical damage on the fatigue life of coiled tubing when exposed to sour environments (i.e. H2S) has not yet been reported in the literature. This paper describes the effect of different types of damage on the material and fatigue life of CT and presents a comparison between "Flexor TU4" predictions and the fatigue life measured for strings with external mechanical damage incurred during service. Also a comparison between the sour fatigue life and that in air is presented in terms of percentages of sweet life (i.e. non-sour) for coiled tubing fatigue samples containing artificially induced mechanical damage on the external surface prior to being exposed to sour environments.

The effect of mechanical damage on corn (Zea mays) storability as determined by carbon dioxide productionand dry matter loss (DML) caused by fungi was quantified. Corn allowable storage time (AST) decreased as percentmechanically damaged kernels increased from 0 to 40%, but AST was relatively constant for damage levels of 40 to 50%.Mechanical damage multipliers were developed for predicting the effect of mechanical damage on corn allowable storagetime. Using total damaged kernels (DKT) determined by official grain graders (mostly mold damage in this study) and theDKT criterion for U.S. No. 2 corn, we found the maximum permissible DML for combine-shelled corn (25 to 35%mechanical damage) to be about 0.35%. This level of dry matter loss is lower than the commonly accepted value of 0.5%.

Fresh fruits like bananas are very susceptible to mechanical damage during postharvest handling which can result in a substantial decline in quality. The study aims to evaluate the effect of bruise damage and storage temperatures on the quality of banana fruits after 48 h storage. Each ‘Grand Naine’ banana fruit was impacted once by using a drop impact test using three different heights (10, 30, and 50 cm) and storage temperatures (13 and 22 °C) after 48 h of storage. Different quality analyses were measured like bruise measurements (impact energy, bruise area, bruise volume, and bruise susceptibility), weight loss, total soluble solids (TSS), color (L*, a*, b*, hue°, chroma, yellowness index, yellowness value) headspace gases (respiration and ethylene production rate). The results showed that bruise measurements (bruise area, bruise volume, and bruise susceptibility) were highly affected by drop height. The quality parameters like weight, color, total soluble solids and headspace gases were affected by drop height and storage condition. Weight loss, total soluble solids, respiration rate, and ethylene production rate increased as drop height and storage temperature rise. Storage at ambient conditions (22 °C) accelerated bruising occurrence in banana fruits. Fewer changes were observed after 48 h of storage. The least value of yellowness index was observed on the non-bruised banana fruits (84.03) under 13 °C storage conditions. The findings of the study can provide baseline data to understand the mechanical damage mechanism on fruit quality, hoping to create awareness and educate farming communities and consumers. Storage temperature management is another approach that needs to be followed to reduce the occurrence of mechanical damage in fresh produce.

The installation process and the occurrence of abrasion may cause unwanted changes on the properties of the geosynthetics. When identified as relevant degradation agents for a given application, their effect has to be properly taken into account during the design phase in order to guarantee that the geosynthetics will perform correctly their functions over time. In this work, a reinforcement geocomposite (formed by a nonwoven polypropylene geotextile reinforced with polyethylene terephthalate filaments) was exposed to the isolated and combined effects of two degradation tests: mechanical damage under repeated loading and abrasion (the geocomposite was tested on both sides, which were structurally different). Damage assessment was performed by visual inspection and tensile tests. Based on the changes occurred in tensile strength, reduction factors were determined. The degradation tests provoked extensive damage on the geocomposite, having a negative impact on its tensile behaviour. Contrary to mechanical damage under repeated loading, the effect of abrasion on the geocomposite was influenced by the side that was tested. Finally, some differences were found between the reduction factors determined by the traditional method (multiplication of reduction factors obtained in isolation for each agent) for the combined effect of mechanical damage under repeated loading and abrasion and those resulting from the successive exposure to both degradation agents.

ABSTRACTThe mechanical damage caused to fruits during transportation shortens their shelf life considerably. This study proposes a method for nondestructive detection of fruit mechanical damage based on electrical parameters. This study developed a flexible electrode capable of nondestructively acquiring electrical parameters from fruits to measure the electrical parameters of minikiwi fruits under varying degrees of mechanical damage. The results demonstrated the excellent flexibility and stable electrical parameter acquisition capability of the fabricated sensor. The impedance value (Z) exhibited a decreasing trend with prolonged damage duration. At 4 Hz, for a damage duration of 0–2 h, the Z difference reached 2,569,406.1 Ω, whereas at 1 MHz, this discrepancy reduced to 1527.3 Ω. As mechanical vibrations disrupt the integrity of the cell walls, leading to a decrease in free water content, these changes collectively result in impedance reduction. The proposed flexible electrodes demonstrated satisfactory bending resistance, tensile strength, and electrical conductivity, making them suitable for integration into robotic arms for real‐time fruit quality assessment during grasping operations. This study provides a theoretical foundation for the development of electrical parameter‐based nondestructive detection systems for assessing fruit mechanical damage.

The changes of hydrogen peroxide (H2O2) metabolism and antioxidant enzyme activities in a hybrid poplar (Populus simonii × P. pyramidalis ‘Opera 8277’) in response to mechanical damage (MD) and herbivore wounding (HW) were investigated to determine whether H2O2 could function as the secondary messenger in the signaling of systemic resistance. Results show that H2O2 was generated in wounded leaves through MD and HW treatments and systemically in unwounded leaves around the wounded leaves. The activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were also enhanced. However, the H2O2 accumulation and antioxidant enzyme activities were inhibited in MD leaves through the pretreatment with DPI (which is a specific inhibitor of NADPH oxidase). The results of this study suggest that H2O2 could be systemically induced by MD and HW treatments, and H2O2 metabolism was closely related to the change in SOD, APX and CAT activities. A high level of antioxidant enzymes could decrease membrane lipid peroxidation levels and effectively induce plant defense responses.

Depositing a tritium permeation barrier on the surface of materials is a key method for reducing tritium permeability. During actual operational processes, the surface of the tritium permeation barrier may experience mechanical damage, such as spalling and scratches. The hydrogen permeability resistance of the coating will degrade due to such forms of mechanical damage. It is a significant engineering challenge to evaluate the impact of these damages on the coating's tritium resistance. In this experiment, the mechanical damage to the FeAl/Al2O3 tritium permeation barrier on 316L stainless steel was simulated through scratching, debonding, and thermal shock. Subsequently, a hydrogen isotope gas drive permeation (GDP) test was conducted. The influence of the degree of mechanical damage on the coating's tritium permeation behavior was assessed and discussed. The results indicate that, under the same damage mechanism, the coating's tritium permeability resistance is positively correlated with the integrity of the coating. Additionally, the impact of scratches on the coating surface is more severe than that of other damage mechanisms.

Mamey sapote fruit ( P. sapota ) with round lanceolate shape, harvested at physiological maturity, were subjected to mechanical compressive yield strength (CYS) and mechanical compression point biocedencia (CPB) in order to evaluate the effect of mechanical damage in the color components: luminosity (L*), Chroma (C*) and hue (h), the firmness, the content of soluble protein (SP) and total phenols (TP) and the enzymatic activity of peroxidase (POD) and polyphenol oxidase (PPO). The color components were not different from the shape of fruit, nor influenced by the compression levels only at 0 and 3 days of evaluation (DOE). During the 9 days of storage in the round shaped fruits subjected to CLE, color components were not affected: L*, C*, h (62.3, 49.8 and 50.9), firmness (32.8 N) and enzyme activity of POD (2109.3 U mg -1 pro) and PFO (52.7 U mg -1 pro). The lanceolate fruits were most affected by the treatments compression, being CPB where lower values of L* (41.0) were presented, C* (25.9), h (47.7), firmness (0.8 N) and FT (229.2 mgg -1 pf) at 6 and 9 DOE; while the values of PS (3001.1 mg kg-1PF) and enzyme activity of POD (2706.1 U mg -1 pro) and PFO (57.5 U mg -1 pro) were elevated at 9 DOE, up to elapse storage. The fruits of Mamey sapote with round shape had lower susceptibility to mechanical damage when subjected to levels of CLE, therefore, the fruit shape influences the resistance to mechanical compression. Mechanical damage by CPB affected postharvest quality and accelerated the maturation process of the Mamey sapote with lanceolate shape.

Thermal diffusivity measurement of SiC fibre reinforced BMAS glass ceramic composites exposed mechanical damage

Tree death is a key process for our understanding of how forests are and will respond to global change. The extensive forests across the southern Amazonia edge—the driest, warmest and most fragmented of the Amazon regions—provide a window onto what the future of large parts of Amazonia may look like. Understanding tree mortality and its drivers here is essential to anticipate the process across other parts of the basin. Using 10 years of data from a widespread network of long‐term forest plots, we assessed how trees die (standing, broken or uprooted) and used generalised mixed‐effect models to explore the contribution of plot‐, species‐ and tree‐level factors to the likelihood of tree death. Most trees died from stem breakage (54%); a smaller proportion died standing (41%), while very few were uprooted (5%). The mortality rate for standing dead trees was greatest in forests subject to the most intense dry seasons. While trees with the crown more exposed to light were more prone to death from mechanical damage, trees less exposed were more susceptible to death from drought. At the species level, mortality rates were lowest for those species with the greatest wood density. At the individual tree level, physical damage to the crown via branch breakage was the strongest predictor of tree death. Synthesis . Wind‐ and water deficit‐driven disturbances are the main causes of tree death in southern Amazonia edge which is concerning considering the predicted increase in seasonality for Amazonia, especially at the edge. Tree mortality here is greater than any in other Amazonian region, thus any increase in mortality here may represent a tipping point for these forests.