Damage Structures Research Articles

Comparative Study of Mode Shapes Curvature and Damage Locating Vector Methods for Damage Detection of Structures

A number of damage detection techniques have been proposed to be applied for structural health monitoring systems. In this paper a comparative study of mode shape curvature and damage locating vector methods were considered for predicting damage of structures. The mode shape curvature method is based on the difference of mode shapes between damage and undamaged structures, while damage locating vector is based on difference of flexibility matrix of damage and undamaged structures. Three type of structures were considered in this paper. The first test structure is a shear building, the second is a beam-type, and the third is a plane truss system. For each type of structures a numerical model is carried out for simulations. Several damage scenarios were considered to evaluate both methods. From the numerical experiment, it can be shown that both methods in general have demonstrated a good sensitivity for damage detections. For shear building and beam structures both methods have the ability to predict the damage locations. Due to the nature of the methods, however, for plane truss structures, while the damage locating vector method can predict the damaged members, the mode shape curvature method can predict only the nodes in the vicinity of the damaged member of plane truss structures.

Contrasts in compliant fault zone properties inferred from geodetic measurements in the San Francisco Bay area

AbstractIn crustal fault zones, regions of damaged rock characterized by reduced elastic shear modulus can influence patterns of near‐field interseismic deformation. In order to study these compliant fault zones (CFZs) and how they might develop over the lifetimes of faults, we compare two fault segments with contrasting fault age and lithology along the San Andreas Fault in the San Francisco Bay Area. New geodetic measurements of the interseismic velocity fields at each location are used to constrain fault zone parameters through a Markov chain Monte Carlo method. At Black Mountain, in the Santa Cruz Mountains of the San Francisco Peninsula, we do not find evidence for a compliant fault zone; instead, we find that the geodetic data are more consistent with a model of a single fault in a homogeneous elastic half‐space. At Lake San Andreas, a younger fault segment 35 km farther north, we find evidence for a compliant fault zone about 3.4 +1.1/−1.4 km wide, containing a shear modulus of about 40% of the shear modulus of the surrounding rock. We also find that the best fitting CFZ model at this location, unlike the best fitting homogeneous half‐space model, has a locking depth that agrees well with the observed depth of microseismicity. Based on differences in fault age, cumulative displacement, and lithology between Black Mountain and Lake San Andreas, we infer that lithology plays an important and, in this case, perhaps a dominant role in the accumulation of fault zone damage structures and the development of CFZs over the lifetime of a fault.

Abstract 4645: Cell cycle specific effects and associated DNA damage of selective inhibitors of nuclear export (SINE)

Abstract Nuclear export of proteins is fundamental for cell growth and function. Selinexor is a SINE compound that is in clinical development for the treatment of different cancers. Selinexor forms a slowly reversible covalent bond to Exportin-1 (XPO1), preventing its association with protein cargos, thereby resulting in their nuclear retention. XPO1 cargos include the majority of tumor suppressor proteins (TSP) and cell cycle regulators such as p53, p21 and p27 that have key roles in cancer progression and drug response. It is unclear how selinexor affects cell cycle progression in individual cells and the subsequent stress and fate of those cells. To elucidate selinexor action, we developed cell lines that stably express fluorescent ubiquitin cell cycle reporters (FUCCI), and followed individual cells longitudinally using continuous time-lapse microscopy for 72 hours. We report that in fibrosarcoma-derived HT-1080 cells that express wildtype p53 and p21, 18% of the initial cell population became arrested with >90% in G1- or S-phase and 40% died with 64% from G1- or early S-phase after a cell cycle delay or arrest. We also found that 42% of cells divided, but the progeny died or arrested in G1- or S-phase of the next cell cycle - often after cell cycle arrest or slowed cell cycle progression. Using FUCCI, we tracked the response of cells treated acutely in specific cell cycle stages. Cells treated in G1-phase most often arrested or died in G1- or S-phase, whereas cells treated in G2-phase usually progressed to cell division. As FUCCI revealed S-phase progression defects and associated cell death, we further characterized this phenotype. Using nucleotide incorporation with fluorescent detection, we observed that as early as 2 hours after selinexor treatment only a subset of cells is undergoing DNA replication. Cells that were able to replicate their DNA are doing that inefficiently as both the rate and maximal levels of nucleotide incorporation are significantly reduced. S-phase arrest and progression defects may manifest as DNA double-strand breaks. We find a strong association between S-phase status and DNA damage. In some cells, the damage occurs within hours of selinexor treatment and appears as a striking cluster of foci. At 8 hours, nearly 35-45% of cells contain DNA damage clusters. Importantly, the damage clusters sometimes repair as determined by fixed cell time-course analysis and live-cell microscopy. We are exploring the nature of these DNA damage structures and the mechanisms of their formation and repair. In summary, selinexor is fast acting, shows cell cycle selectivity, results in DNA damage and is highly effective at arresting cell growth and inducing apoptosis in tumor cells. These data suggest that selinexor may exert anti-cancer effects even on slow growing tumors where the bulk of the cell mass presents a G1-like state and that it likely combines well with other cell cycle targeted therapeutics. Citation Format: Russell T. Burke, Joshua Marcus, John DeSisto, Yosef Landesman, James D. Orth. Cell cycle specific effects and associated DNA damage of selective inhibitors of nuclear export (SINE). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4645.

Stent migration and bail-out strategies.

Stent migration is an inherent complication of stent deployment. A number of factors are responsible for this dreaded complication. The stent may eventually migrate to the heart or lungs or in the process of migration damage structures en route to its final destination. A number of techniques are available to bail out interventionalists if such a situation should arise. Occasionally a wait and watch approach may be prudent.

Lasting mantle scars lead to perennial plate tectonics.

Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a ‘perennial' phenomenon.

Molecular dynamics study on the thickness of damage layer in multiple grinding of monocrystalline silicon

The molecular dynamic (MD) simulation of monocrystalline silicon under multiple grinding is carried out to study the effect of multiple grinding on the thickness of damage layer. Four grinding processes are conducted on (001) along 〈−100〉 direction. The depth of grinding of the first grinding is 20Å. The subsequent grinding is machining on the machined surface with a damage layer left by the first grinding. The second grinding is a spark-out process and the depth of grinding of the third and fourth grinding increases by 5Å compared with the previous grinding. The changes of structures and mechanical properties of the damage layer in the machined surface after the first grinding are investigated by coordination number (CN), the radial distribution functions (RDF) and nanoindentation. The thickness of the damage layer left by the first grinding can be reduced stably in the second and third grinding, but it will increase in the fourth grinding. Therefore, two more grinding steps between the third and fourth grinding are carried out. One is the spark-out process and the depth of grinding of the other increases by 2Å compared with the third grinding. The results show the spark-out process can remove the springback left by the previous grinding and promote the residual compressive stress in the machined surface, which can improve the accuracy and quality of grinding. The thickness of damage layer induced by the first grinding can be reduced without new damage structures generating. However, it cannot be reduced unlimited. When the thickness of damage layer reaches half of the original thickness, a re-grinding will cause new damage structures, and the thickness of damage layer will increase. The depth of grinding is suggested to be less than half of the original damage thickness to reduce the damage layer. The research results can be applied in the ultra-precision grinding of monocrystalline silicon to control the thickness of damage layer and improve the quality of machining.

Ni ion damage structures and hardness changes in austenitic stainless steels and their model alloys

Defect structures of austenitic stainless steels and their model alloys after 6 MeV Ni ion irradiation were studied using positron annihilation lifetime measurements and Vickers hardness obtained from micro-hardness measurements. After irradiation at room temperature, a long lifetime of 150-180 ps was obtained and the Vickers hardness increased with increasing the irradiation dose. After irradiation at 573 K, all the alloys exhibited lifetime spectra that were not decomposed into two components. Their hardness also increased with the irradiation dose, but the enhancement was small compared with that at room temperature. Defects introduced by the ion irradiation could be detected near the surface using a Na-22 source. The hardness is correlated with the density and size of the defect clusters.

Comparative Investigations of the Surface Damage of Monocrystalline Silicon Wafers by Scanning Infrared Reflection Examination and Raman Spectroscopy

Mechanical preparation of mono-and multicrystalline silicon wafers by sawing, lapping, or grinding damages the surface. Depending on the mechanical impact of the treatment different degrees of damage structures occur. It is necessary for further processing of wafers to have damage free and contactless methods to characterize structures such as changes of the lattice structure by phase transformations or plastic deformations, and microcracks below the surface. In this paper we present results of investigations on the sub-surface damage by two contactless optical methods: Scanning infrared reflection polarimetry with SIREX and Raman spectroscopy. The investigations were carried out on silicon wafers sawn with the multi-wire technique using diamond coated wires. The sub-surface damage mainly consists of microcracks of different length, which penetrate several micrometers into the bulk. The results were compared with confocal microscopy and scanning electron microscopy analyses of the same damage structures.

Cancer treatment in determination of hearing loss

IntroductionChemotherapy and radiotherapy in oncology have repercussions in hearing health, and can damage structures of the inner ear. These repercussions usually, result in a bilateral and irreversible hearing loss. ObjectiveTo identify sensorineural hearing loss cases with complaints of tinnitus and difficulty in speech understanding and investigate their relationship with the types of chemotherapy and radiotherapy the patients received. MethodsCross-sectional, clinical, observational, analytical, historical cohort study of 58 subjects treated in a public hospital in the state of Sergipe, diagnosed with neoplasia. The subjects were submitted to anamnesis, conventional pure tone audiometry, and speech recognition threshold. ResultsOf the 116 ears, 25.9% presented sensorioneural hearing loss characterized by changes in high frequencies. There was a positive correlation between hearing loss and the association of chemotherapy and radiotherapy (p=0.035; R=0.196). The auditory complaint analysis shows that most of the subjects had tinnitus and speech understanding difficulty, even with a normal auditory threshold. ConclusionsCancer treatment causes hearing loss, associated with the administration of chemotherapy and radiotherapy. Cyclophosphamide increased the risk of causing hearing loss. Complaints of tinnitus and speech understanding difficulty were observed.

Delineation of large localized damage structures forming ahead of an active mining front by using advanced acoustic emission mapping techniques

We applied advanced mapping techniques to 291 230 acoustic emission (AE) events as small as around M −4 that were recorded over 50 days by an ultra-high resolution network close to the active front of a tabular mining stope being advanced northward at 1km depth in the Cooke 4 Gold Mine in South Africa. We first applied joint hypocenter determination (JHD) to improve absolute locations, and then applied the double-difference relative location algorithm to the JHD output. These steps resolved the seemingly continuous, dense cloud of AEs that extend about 20m ahead of the stope front into several discrete, steeply dipping tabular clusters a few meters thick and 10–30m in dip extent, separated by quiet intervals a few meters thick. The clusters have a strike parallel to the stope face and a dip of about 65°, resembling commonly observed large shear fractures along the plane of maximum shear (Ortlepp shears). In general, the activity of the clusters changed in similar ways as the stope face advanced, but each cluster remained stationary and the gaps between clusters were impressively quiet. This study demonstrates that high-resolution AE mapping can delineate the formation of large structures of localized damage in the highly stressed intact rock mass ahead of the stope face, a process that may culminate in hazardous seismic events.

Micro- and nano-scale damage on the surface of W divertor component during exposure to high heat flux loads with He

Micro- and nano-scale surface damage on a W divertor component sample exposed to high heat flux loads generated with He atoms has been investigated through SEM, EBSD, AFM and FIB-SEM. The component sample was supplied by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) and AT&M company, China, and the loading experiment was performed in the GLADIS facility at IPP Garching, Germany. Two typical damage structures were observed on the surface: the first one is characterized by obvious blisters and some grooves formed from ruptured blisters, and the other one is a kind of porous structure accompanying with at least ∼25 nm surface material loss. As the grain orientation is further away from <111>, the damage morphology gradually changes from the former structure to the latter. The possible damage mechanism is discussed.

Abstract 1760: Single cell longitudinal studies reveal cell cycle specific effects of selective inhibitors of nuclear export (SINE)

Abstract Nuclear export of proteins is fundamental for cell growth and function. Selinexor is a SINE compound that is in clinical development for the treatment of different cancers. Selinexor forms a slowly reversible covalent bond to Exportin-1 (XPO1), preventing its association with protein cargos, thereby resulting in their nuclear retention. XPO1 cargos include the majority of tumor suppressor proteins (TSP) and cell cycle regulators such as p53, p21 and p27 that have key roles in cancer progression and drug response. It is unclear how selinexor affects cell cycle progression in individual cells and the subsequent stress and fate of those cells. To elucidate selinexor action, we developed cell lines that stably express fluorescent ubiquitin cell cycle reporters (FUCCI), and followed individual cells longitudinally using continuous time-lapse microscopy for 72 hours. We report that in fibrosarcoma-derived HT-1080 cells that express wildtype p53 and p21, 20% of the initial cell population became arrested with &amp;gt;90% in G1- or S-phase and 35% died with nearly 70% from G1- or S-phase after a cell cycle delay or arrest. We also found that 45% of cells divided, but the progeny died or arrested in G1- or S-phase of the next cell cycle - often after cell cycle arrest or slowed cell cycle progression. Using FUCCI, we tracked the response of cells treated acutely in specific cell cycle stages. Cells treated in G1-phase most often arrested or died in G1- or S-phase, whereas cells treated in G2-phase usually progressed to cell division. As FUCCI revealed S-phase progression defects and associated cell death, we further characterized this phenotype. Using nucleotide incorporation with fluorescent detection, we find that as soon as 8 hours after selinexor fewer cells are undergoing DNA replication and those that are, are doing so inefficiently as both the rate and maximal levels of nucleotide incorporation are significantly reduced. S-phase arrest and progression defects may manifest as DNA double-strand breaks. We find a strong association between S-phase status and DNA damage. In some cells, the damage occurs within hours of selinexor treatment and appears as a striking cluster of foci. At 8 hours, nearly 50% of cells contain DNA damage clusters. Importantly, the damage clusters sometimes repair as determined by fixed cell time-course analysis and live-cell microscopy. We are exploring the nature of these DNA damage structures, the mechanisms of their formation and repair, and are also testing for redundancy of the cell cycle regulators in determining selinexor responses. In summary, selinexor is fast acting, shows cell cycle selectivity, and is highly effective at arresting cell growth and inducing apoptosis in tumor cells. These data suggest that selinexor may exert anti-cancer effects even on slow growing tumors where the bulk of the cell mass presents a G1-like state and that it likely combines well with other cell cycle targeted therapeutics. Citation Format: Russell T. Burke, Joshua M. Marcus, John DeSisto, Yosef Landesman, James D. Orth. Single cell longitudinal studies reveal cell cycle specific effects of selective inhibitors of nuclear export (SINE). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1760. doi:10.1158/1538-7445.AM2015-1760

Cluster dynamics models of irradiation damage accumulation in ferritic iron. II. Effects of reaction dimensionality

The black dot damage features which develop in iron at low temperatures exhibit significant mobility during in situ irradiation experiments via a series of discrete, intermittent, long range hops. By incorporating this mobility into cluster dynamics models, the temperature dependence of such damage structures can be explained with a surprising degree of accuracy. Such motion, however, is one dimensional in nature. This aspect of the physics has not been fully considered in prior models. This article describes one dimensional reaction kinetics in the context of cluster dynamics and applies them to the black dot problem. This allows both a more detailed description of the mechanisms by which defects execute irradiation-induced hops while allowing a full examination of the importance of kinetic assumptions in accurately assessing the development of this irradiation microstructure. Results are presented to demonstrate whether one dimensional diffusion alters the dependence of the defect population on factors such as temperature and defect hop length. Finally, the size of interstitial loops that develop is shown to depend on the extent of the reaction volumes between interstitial clusters, as well as the dimensionality of these interactions.

Sol–gel synthesis of magnetic TiO2 microspheres and characterization of their in vitro heating ability for hyperthermia treatment of cancer

Common cancer treatments are invasive and lack specificity, leading to unwanted side effects. Because hyperthermia can kill cancer cells and damage proteins and structures within cells, it has been considered a novel, minimally invasive cancer treatment. However, many hyperthermia treatments cannot heat deep-seated tumors effectively and locally. Heat-generating magnetic microspheres can help address this challenge. However, current research has not produced microspheres that can be sufficiently heated. We prepared magnetic titania (TiO2) microspheres by introducing magnetite nanoparticles (MNPs) into the sol–gel process during water-in-oil emulsion for in situ hyperthermia treatment of cancers. Two types of MNPs were used in this study: One type was synthesized by a chemical coprecipitation method, and the other type was commercially available MNPs. The obtained microspheres contained up to 46.7 wt% MNPs, and their saturation magnetization and coercive force were 34.2 emu/g and 103 Oe, respectively. The particles’ in vitro heating efficiency in an agar phantom was measured in an alternating magnetic field of 300 Oe and 100 kHz. The temperature increase in the agar phantom within 300 s was 4.5 °C for microspheres with MNPs that were synthesized by chemical coprecipitation and 53 °C for microspheres with commercially available MNPs. The excellent heating efficiency of the microspheres may be attributed to the hysteresis losses of the magnetic particles. These microspheres are believed to be promising thermoseeds for hyperthermic treatment of cancer. Magnetic TiO2 microspheres with a diameter of 7–15 μm were obtained by directly introducing preformed magnetic MNPs into a sol–gel process from TTIP in water-in-oil emulsion. The magnetic TiO2 microspheres containing Fe3O4 at a content higher than 46 wt% increased the temperature of the agar phantom to above 43 °C in 3 min. They are expected to be useful for arterial embolization hyperthermic treatment of cancer, but control of their diameter is essential.

Radiation hardness of n-type SiC Schottky barrier diodes irradiated with MeV He ion microbeam

We studied the radiation hardness of 4H-SiC Schottky barrier diodes (SBD) for the light ion detection and spectroscopy in harsh radiation environments. n-Type SBD prepared on nitrogen-doped (∼4×1014cm−3) epitaxial grown 4H-SiC thin wafers have been irradiated by a raster scanning alpha particle microbeam (2 and 4MeV He2+ ions separately) in order to create patterned damage structures at different depths within a sensitive volume of tested diodes. Deep Level Transient Spectroscopy (DLTS) analysis revealed the formation of two deep electron traps in the irradiated and not thermally treated 4H-SiC within the ion implantation range (E1 and E2). The E2 state resembles the well-known Z1/2 center, while the E1 state could not be assigned to any particular defect reported in the literature. Ion Beam Induced Charge (IBIC) microscopy with multiple He ion probe microbeams (1–6MeV) having different penetration depths in tested partly damaged 4H-SiC SBD has been used to determine the degradation of the charge collection efficiency (CCE) over a wide fluence range of damaging alpha particle. A non-linear behavior of the CCE decrease and a significant degradation of the spectroscopic performance with increasing He ion fluence were observed above the value of 1011cm−2.

Earthquake Barcode from a Single-Degree-of-Freedom System

Earthquake is a violent and irregular ground motion that can severely damage structures. In this paper we subject a single-degree-of-freedom system, consisting of spring and damper, to an earthquake excitation, and meanwhile investigate the response behavior from a novel theory about the dynamical system, by viewing the time-varying signum function of It can reflect the characteristic property of each earthquake through and the second component of f, where is a time-sampling record of the acceleration of a ground motion. The barcode is formed by plotting with respect to time. We analyze the complex jumping behavior in a barcode and an essential property of a high percentage occupation of the first set of dis-connectivity in the barcode from four strong earthquake records: 1940 El Centro earthquake, 1989 Loma earthquake, and two records of 1999 Chi-Chi earthquake. Through the comparisons of four earthquakes, we can observe that strong earthquake leads to large percentage of the first set of dis-connectivity.

Very low electron temperature in warm dense matter formed by focused picosecond soft x-ray laser pulses

We investigated the optical emission from the ablating surfaces induced by the irradiations of soft x-ray laser (SXRL) pulses with the aim of estimation of the maximum electron temperature. No emission signal in the spectral range of 400–800 nm could be observed despite the formation of damage structures on the target surfaces. Hence, we estimated an upper limit for the electron temperature of 0.4–0.7 eV for the process duration of 100–1000 ps. Our results imply that the ablation and/or surface modification by the SXRL is not accompanied by plasma formation but is induced by thermo-mechanical pressure, which is so called a spallative ablation. This spallative ablation process occurs in the low electron temperature region of a non-equilibrium state of warm dense matter.

Repair of shear-deficient normal weight concrete beams damaged by thermal shock using advanced composite materials

The use of advanced composite materials such as Fiber Reinforced Polymers (FRPs) in repairing and strengthening reinforced concrete structural elements has been increased in the last two decades. Repairing and strengthening damage structures is a relatively new technique. The aims of this study was to investigate the efficiency and effectiveness of using Carbon Fiber Reinforced Polymer (CFRP) to regain shear capacity of shear-deficient normal weight high strength RC beams after being damaged by thermal shock. Sixteen high strength normal weight RC beams (100×150×1400mm) were cast, heated at 500°C for 2h and then cooled rapidly by immersion in water, repaired, and then tested under four-point loading until failure. The composite materials used are carbon fiber reinforced polymer plates and sheets. The experimental results indicated that upon heating then cooling rapidly, the reinforced concrete (RC) beams exhibited extensive map cracking without spalling. Load carrying capacity and stiffness of RC beams decreased about 68% and 64%, respectively, as compared with reference beams. Repairing the thermal damaged RC beams allowed recovering the original load carrying without achieving the original stiffness. Repaired beams with CFRP plates with 90° and 45° regained from 90% to 99% of the original load capacity with a corresponding stiffness from 79% to 95%, whereas those repaired with CFRP sheet on the web sides and a combination of CFRP plates and sheet regained from 102% to 107% of the original load capacity with a corresponding stiffness from 81% to 93%, respectively. Finally, finite element analysis model is developed and validated with the experimental results. The finite element analysis showed good agreement as compared with the experimental results in terms of load–deflection and load–CFRP strain curves.

Subsurface failure in spherical bodies: A formation scenario for linear troughs on Vesta’s surface

Many asteroids in the Solar System exhibit unusual, linear features on their surface. The Dawn mission recently observed two sets of linear features on the surface of the asteroid 4 Vesta. Geologic observations indicate that these features are related to the two large impact basins at the south pole of Vesta, though no specific mechanism of origin has been determined. Further, the orientation of the features is offset from the center of the basins. Experimental and numerical results reveal that the offset angle is a natural consequence of oblique impacts into a spherical target. Here we demonstrate that a set of shear planes develops in the subsurface of the body opposite to the point of first contact. These subsurface failure zones then propagate to the surface under combined tensile-shear stress fields after the impact to create sets of approximately linear faults on the surface. Comparison between the orientation of damage structures in the laboratory and failure regions within Vesta can be used to constrain impact parameters (e.g., the approximate impact point and likely impact trajectory).

Damage structures in leaf epidermis and cuticle as an indicator of elevated atmospheric sulphur dioxide in early Mesozoic floras

Volcanic episodes are considered to be potentially important drivers of many mass extinction events in Earth history, when a sharp decrease in the diversity and abundance of macroscopic organisms occurred. Such events are hypothesised to be associated with volcanic sulphur dioxide (SO2) release. The effect of volcanism on atmospheric composition varies widely and is related to the magnitude and duration of the volcanic episode. Currently, there are limited methods for detecting the timing of SO2 release in the geological past. In field conditions, the influence of SO2 on plants can be difficult to separate from the effects of other volcanic emissions, which enter via stomata and can affect plant physiology, anatomy and morphology. In order to assess the direct effects of SO2 associated with palaeo-volcanic episodes, we conducted a six month growth chamber experiment growing plants under control (zero parts per million (ppm)) and continuous elevated (0.2ppm) sulphur dioxide atmospheres. Leaf morphological responses of ten species representative of Mesozoic gymnosperm and fern fossil floras were examined using cryo-scanning electron microscopy. Here we show that expanded, fully mature leaves record unambiguous damage structures associated with injury from SO2 fumigation. In SO2 treated plants, leaves were smaller and did not persist; distinct raised areas of cuticle surrounding stomata appeared; surface waxes altered; blistering of the cuticle occurred; and the stomatal complex became distorted. These results have clear implications for application to the fossil record as many of the observed damage structures have the potential to be preserved in fossil plant cuticle and thus allow precise pinpointing of elevated SO2 episodes in the geological past.