Striation Pattern Research Articles

Design and implementation of a non-resonant vibration-assisted machining device to create bespoke surface textures

Non-resonant vibration-assisted machining involves the superposition of controlled vibrations onto traditional machining processes such as turning or milling. In this study, a novel variant of this technique has been investigated using an off-the-shelf piezoelectric actuator to create bespoke surface textures in a conventional milling machine. The purpose of these surfaces is to provide enhanced tribological performance by reserving lubricant, trapping and discharging debris and wear particles, and delaying the collapse of the full hydrodynamic lubricant film. Surface textures consisting of a repeating radial striation pattern of sine waves were reproducibly generated on the face of the disc work piece (an aluminium alloy AlSi1MgMn and a low-alloyed steel 16MnCr5) when the frequency of the superposed vibration was in phase with the rotational speed of the work piece. The texture parameters were controllable from approximately 1 mm to 8 mm in the wavelength and from a few microns to 25 µm in the peak to peak amplitudes which would reasonably cover the range of hydrodynamic lubrication film thickness.

Passive ranging of surface source using bottom bounced sound in deep water

Bottom bounced pattern in deep water interprets the pattern under which rays arrive at the receiver through the paths hitting the bottom boundary once, and it is of great importance in underwater acoustic detection in shadow zone. Based on the ray theory, the bottom bounced sound field in deep water is mostly contributed by four eigenrays including bottom-reflected (BR) path, surface-bottom-reflected (SBR) path, bottom-surface-reflected (BSR) path and surface-bottom-surface-reflected (SBSR) path, all of which arrive at different time with different time delay. On the basis of the time delay of four eigenrays, the interference striation pattern of the bottom bounced sound field can be derived. From the derivation, it can be found that the striation appears periodic in the frequency domain at a certain source-receiver range, and the period increases with range increasing. As the frequency period corresponds to the reciprocal of multipath time delay, the range can be estimated by the time delay. As for a near-surface target source, surface reflection at the source could always be neglected, and then the sound field can be thought of as the contribution of BR path and BSR path. As a result, the frequency period of its striation corresponds to the reciprocal of the time delay between BR path and BSR path. In this paper, the relationship between the time delay and range is obtained by analyzing the interference striation pattern of the bottom bounced sound field in deep water, and then it is applied to passive ranging of surface sources. The approach is demonstrated valid by the simulated data. Experimental results shows that the range of the surface source can be estimated effectively, with an estimation error less than 5%.

Abstract 3598: Laser micro-irradiations of large amounts of cells for high content applications

Abstract A new methodical approach for the evaluation of photo-manipulated samples is presented and tested in various biological setups. The method is based on an atypical setting of a standard laser-scanning microscope (LSM) and image-processing software solution. Newly, a whole population of several dozen of cells is simultaneously micro-irradiated by a laser beam in a precisely defined pattern of collinear rays. Such laser induced striation pattern is automatically analyzed by specialized software routine providing quantitative assessment of various photo-manipulations, such as DNA-damage induced protein translocations or modifications, in both live and fixed cells. Automation of the process reduces workload and opens new possibilities for various dynamic studies and/or high content experiments. Results obtained during the testing of the method are presented and offer an insight into several DNA damage recognition and response pathways. Citation Format: Martin Mistrik, Eva Vesela, Tomas Furst, Ivo Frydrych, Jan Gursky, Jiri Bartek. Laser micro-irradiations of large amounts of cells for high content applications. [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 3598.

Molecular and automated identification of the diatom genus Frustulia in northern Europe

Molecular-assisted alpha taxonomy, which combines molecular species delimitation with post-hoc morphological examinations, has proved to be an effective tool for the classification of morphologically similar species. We employed this approach to examine the diversity of the genus Frustulia in northern Europe. First, we used two molecular markers to delimit species and then characterized their morphology using conventional and geometric morphometrics. Next, we employed machine-learning methods to identify valves in benthic diatom communities in order to infer the distribution and pH preference of individual species. Unlike previous studies using automated identification of diatom species, we examined the performance of the semi-supervised classifier. Supervised methods, which have been used before, only employ labelled valves to train the classification algorithm. The semi-supervised approach is, in addition, able to benefit from unlabelled valves in the natural populations. It is usually superior in cases in which there are few labelled data available. Finally, we compared the classification accuracy of the algorithms and five volunteer specialists. We found five molecular lineages, the F. crassinervia-saxonica species complex, F. gaertnerae, F. septentrionalis, F. krammeri, and F. cf. maoriana. The most valuable characteristics for species identification were length, width, striation pattern, and allometric shape changes described by the first axis in the geometric morphometric analysis. We found that a semi-supervised approach that does not rely solely on the morphology of isolated cells, but also accounts for variation among valves from natural populations, has superior performance. Based on valves from natural populations, we observed marked differences in species abundances and pH tolerances that have a bearing on their geographical distributions.

Striations in PageRank-ordered matrices

Patterns often appear in a variety of large, real-world networks, and interesting physical phenomena are often explained by network topology as in the case of the bow-tie structure of the World Wide Web, or the small-world phenomenon in social networks. The discovery and modeling of such regular patterns has a wide application from disease propagation to financial markets. In this work, we describe a newly discovered regularly occurring striation pattern found in the PageRank ordering of adjacency matrices that encode real-world networks. We demonstrate that these striations are the result of well-known graph-generation processes resulting in regularities that are manifested in the typical neighborhood distribution. The spectral view explored in this paper encodes a tremendous amount about the explicit and implicit topology of a given network, so we also discuss the interesting network properties, outliers and anomalies that a viewer can determine from a brief look at the re-ordered matrix.

Measured depth-dependence of waveguide invariant in shallow water with a summer profile.

Acoustic-intensity striation patterns were measured in the time-frequency domain using an L-shaped array and two simultaneously towed broadband (350-650 Hz) sources at depths above and below the thermocline under summer profile conditions. Distributions of the waveguide invariant parameter β, extracted from the acoustic striation patterns, peak at different values when receivers are above or below the thermocline for a source that is below the thermocline. However, the distributions show similar characteristics when the source is above the thermocline. Experimental results are verified by a numerical analysis of phase slowness, group slowness, and relative amplitudes of acoustic modes.

Seed micromorphology and its taxonomic significance to Xyris (Xyridaceae, Poales)

The seed micromorphology was studied in eight species of Xyris (Xyridaceae) with taxonomic purposes. The results show that the presence of longitudinal endotegmic ridges in the seed coat is a pattern for the genus and that the shape of these ridges differentiates among the species. The following characteristics are also useful to identify the species: shape and size of the seed, number of cell rows between the ridges, and the striation pattern of the seed coat. Based on these characteristics, a standard terminology is proposed to describe the seed coat in species of the genus. An identification key for the studied species is also provided.

Cells and Stripes: A novel quantitative photo-manipulation technique.

Laser micro-irradiation is a technology widely used in the DNA damage response, checkpoint signaling, chromatin remodeling and related research fields, to assess chromatin modifications and recruitment of diverse DNA damage sensors, mediators and repair proteins to sites of DNA lesions. While this approach has aided numerous discoveries related to cell biology, maintenance of genome integrity, aging and cancer, it has so far been limited by a tedious manual definition of laser-irradiated subcellular regions, with the ensuing restriction to only a small number of cells treated and analyzed in a single experiment. Here, we present an improved and versatile alternative to the micro-irradiation approach: Quantitative analysis of photo-manipulated samples using innovative settings of standard laser-scanning microscopes. Up to 200 cells are simultaneously exposed to a laser beam in a defined pattern of collinear rays. The induced striation pattern is then automatically evaluated by a simple algorithm, which provides a quantitative assessment of various laser-induced phenotypes in live or fixed cells. Overall, this new approach represents a more robust alternative to existing techniques, and provides a versatile tool for a wide range of applications in biomedicine.

Surface morphological features of fiber laser cutting of AA2219 aluminum alloy

High-power fiber laser cutting of AA2219 aluminum alloy was studied. The cutting surface morphologies were examined by optical stereoscopic microscope, and the characteristic sizes were measured by a Vernier caliper. The results showed that the cutting surface was grouped into three zones featured by different striation patterns from the upper to the bottom, which are horizontal striation zone at the upper, vertical striation zone at the middle, and oblique striation zone at the lower. The oblique striation zone was the roughest zone. An optimal range of laser line energy to get an accepted cutting surface both with a small fraction of oblique striation zone and less dross was found, which was determined as 25–35 J/mm. The formation mechanisms of surface features were summarized by the interaction between the gas flow inside the cut and the forces exerted on the molten pool.

Morphological, developmental, and ecological characteristics of the suctorian ciliate Ephelota gigantea (Ciliophora, Phyllopharyngea, Ephelotidae) found on cultured wakame seaweed in Northeastern Japan

Wakame seaweed is an important aquatic resource in Iwate Prefecture. However, a suctorian Ephelota gigantea sometimes causes great damage to wakame culture. Since little is known about the biological characteristics of E. gigantea , its detailed morphology and temporal change of biological characteristics during the 2010 culture season were investigated. Scanning electron microscope observations showed that E. gigantea had different striation patterns on the stalk; there was a swell made of cement by which the stalk was attached to wakame firmly; and the buds had cilia arranged in concentric circles about a ring in the center of the ventral side. A suctorian parasite was found to infect E. gigantea , and the infection seemed to have decreased drastically the attached density of E. gigantea on wakame. Cell size of parasite-infected E. gigantea individuals was larger than that of uninfected individuals, probably because larger E. gigantea has larger surface area for attachment of the parasite. Cyst formation or conjugating individuals were not observed.

Novel morphological macular findings in juvenile CLN3 disease

AimsJuvenile CLN3 disease, one of the most common forms of a group of lysosomal storage diseases called neuronal ceroid lipofuscinoses (NCLs), is a progressive neurodegenerative disorder with initial visual deterioration....

Two new Navicula species (Bacillariophyceae) from Western Europe

During a survey of some springs in the French Central Massif, a new Navicula species (Bacillariophyceae) was found: Navicula sanctamargaritae Beauger sp. nov. A second new Navicula species was observed during a routine biomonitoring project in Flanders: Navicula flandriae Van de Vijver & A.Mertens sp. nov.. The new species are formally described using light and scanning electron microscopy. Both species present a unique set of morphological characters including the structure of the central raphe endings, the striation pattern, the valve dimensions and outline, which allows their separation from similar Navicula taxa such as N. korzeniewskii, N. recens or N. cincta. The ecological preferences of each species are briefly discussed.

Eigenanalysis-Based Adaptive Interference Suppression and Its Application in Acoustic Source Range Estimation

Passive localization of weak sources in the presence of strong interferences is generally a difficult task. In this paper, an eigenanalysis-based adaptive interference suppression (EAAIS) method is proposed for estimating the bearing and subsequently the weak source range. Assuming the target of interest (TOI) is in a known bearing sector, first we define a contribution ratio for each eigenvector of the cross-spectral density matrix (CSDM). The eigenvectors not dominated by the TOI are adaptively identified and removed for interference suppression. The remaining eigenvectors are then used to reconstruct the CSDM for TOI bearing estimation. Finally, the acoustic source range estimation is achieved with the reconstructed CSDM, by matching the beam intensity striation pattern, where it is not required to estimate the waveguide-invariant parameter. The effectiveness of the proposed TOI localization is demonstrated using several experimental data sets.

Sellaphora smirnovii (Bacillariophyta, Sellaphoraceae), a new small-celled species from Lake Glubokoe, European Russia, together with transfer of Navicula pseudoventralis to the genus Sellaphora

A new small-celled species of the genus Sellaphora is described from Lake Glubokoe (Moscow Region, European Russia). For another taxon (also small-celled), a new combination in the same genus is proposed. Both species were studied with light and scanning electron microscopy. Analysis of valve morphology supported assignment to the genus Sellaphora. Sellaphora smirnovii sp. nov. is morphologically most similar to S. pulchra, however it differs from the latter in shape of valve apices, striation pattern and absence of a marginal fold. This taxon is also compared to other morphologically similar species. Navicula pseudoventralis is transferred to the genus Sellaphora as Sellaphora pseudoventralis comb. nov. Observations on S. pseudoventralis showed the presence of biseriate striae, similar to those found in S. seminulum and S. barae.

Achnanthidium petuniabuktianum sp. nov. (Achnanthidiaceae, Bacillariophyta), a new representative of the A. pyrenaicum group from Spitsbergen (Svalbard Archipelago, High Arctic)

During a survey of the freshwater littoral diatom flora from lakes and ponds in the region of Petuniabukta on Spitsbergen (Svalbard Archipelago, High Arctic region), a new Achnanthidium species, A. petuniabuktianum sp. nov., has been recorded. Achnanthidium petuniabuktianum is a new representative of the A. pyrenaicum group as evidenced by its curved distal raphe fissures. The present paper describes in detail the morphology of A. petuniabuktianum based on light and scanning electron microscopy. The new taxon is characterized in having linear valves with parallel margins and broadly rounded, never protracted apices and a characteristic—in light microscopy hardly discernible—striation pattern consisting of very short striae composed of one or two small, always slit-like areolae. Based on current results, Achnanthidium petuniabuktianum is a benthic taxon occurring in epilithic and epiphytic habitats in the littoral zones of freshwater lakes and ponds.

Fatigue performance of biodegradable magnesium–calcium alloy processed by laser shock peening for orthopedic implants

Permanent orthopedic implants made from titanium, stainless steel, or cobalt–chromium alloys cause stress shielding and lead to secondary surgery. Biodegradable magnesium–calcium (MgCa) alloys have the potential to minimize stress shielding as well as eliminate the need for secondary surgery. The critical technical challenge is that magnesium degrades rapidly in the human body. In order to slow the corrosion rate, surface treatments such as laser shock peening (LSP), shot peening, or burnishing have been reported in literature. Each of these surface treatments uniquely alters the surface integrity and consequent fatigue life. Even though surface treatments may be effective at slowing corrosion rates, it is important to ensure that they do not shorten fatigue life. The purpose of this study was to (1) develop a laser shock peening (LSP) surface treatment of a curved surface that adjusts the surface integrity of a MgCa alloy by varying the peening overlap ratio and (2) determine the effect of LSP on the fatigue life. Surface integrity was characterized by topography, microstructure, and microhardness. Fatigue life of laser peened and unpeened samples were measured by rotating bending fatigue tests. It was found that LSP increased the fatigue life of the peened MgCa samples. Implementing LSP at high overlap ratios reduced the surface pile-up which resulted in a higher fatigue life. The fractured surfaces of the peened samples exhibited striation patterns which were more pronounced at higher peening overlap ratios.

Passive acoustic observations of tide height in the Iroise Sea using ambient noise.

Considering a broadband motionless source in a waveguide with a depth that varies with time, the time-frequency representation of the acoustic intensity shows a striation pattern than can be explained using the depth-frequency waveguide invariant. This phenomenon is used here to describe acoustic data recorded in the Iroise Sea, where intense tides occur. The originality of this study is that the acoustic data consist of only ambient noise. The best hypothesis is that these striations are created by distant marine traffic in the Bay of Brest, and the results suggest that tide height can be monitored using long-term passive acoustics.

Early-life perturbations in glucocorticoid activity impacts on the structure, function and molecular composition of the adult zebrafish (Danio rerio) heart

BackgroundTransient early-life perturbations in glucocorticoids (GC) are linked with cardiovascular disease risk in later life. Here the impact of early life manipulations of GC on adult heart structure, function and gene expression were assessed. Methods and resultsZebrafish embryos were incubated in dexamethasone (Dex) or injected with targeted glucocorticoid receptor (GR) morpholino knockdown (GR Mo) over the first 120 h post fertilisation (hpf); surviving embryos (>90%) were maintained until adulthood under normal conditions. Cardiac function, heart histology and cardiac genes were assessed in embryonic (120 hpf) and adult (120 days post fertilisation (dpf)) hearts.GR Mo embryos (120 hpf) had smaller hearts with fewer cardiomyocytes, less mature striation pattern, reduced cardiac function and reduced levels of vmhc and igf mRNA compared with controls. GR Mo adult hearts were smaller with diminished trabecular network pattern, reduced expression of vmhc and altered echocardiographic Doppler flow compared to controls. Dex embryos had larger hearts at 120 hpf (Dex 107.2 ± 3.1 vs. controls 90.2 ± 1.1 μm, p < 0.001) with a more mature trabecular network and larger cardiomyocytes (1.62 ± 0.13 cells/μm vs control 2.18 ± 0.13 cells/μm, p < 0.05) and enhanced cardiac performance compared to controls. Adult hearts were larger (1.02 ± 0.07 μg/mg vs controls 0.63 ± 0.06 μg/mg, p = 0.0007), had increased vmhc and gr mRNA levels. ConclusionPerturbations in GR activity during embryonic development results in short and long-term alterations in the heart.

193 Impact of Glucocorticoid Induced Reprogramming on Functional, Histological and Molecular Signalling in the Adult Zebrafish Heart

Introduction Foetal over-exposure to glucocorticoids (GC) has been associated with cardiovascular disorder in later life however the impact of transient early life alterations in GC activity on the heart itself has not been widely studied. We explored this using short term pharmacological and molecular modification of GC activity during the first 120 h of development in the zebrafish by assessing short and long term effects on the structure, function and molecular composition of the heart. Methods Zebrafish embryos (ZFe) were incubated in dexamethasone (Dex) during the first 120 h post fertilisation (hpf) or underwent injection of eggs with a targeted glucocorticoid receptor (GR) morpholino knockdown (GR MO). Embryos surviving to 120hpf (>90%) were then allowed to develop to adulthood under normal conditions. Cardiac function was assessed at 120hpf by ejection fraction, ventricle cardiomyocyte number (DAPI staining), histology and qPCR. Adult hearts were assessed using cardiac ultrasound (VisualSonics), histology and qPCR at 120 days post fertilisation. Results In the embryo (120 hpf), Dex-treatment resulted in larger hearts (Dex 107.2 ± 3.1 vs. controls 90.2 ± 1.1 µm, p < 0.001) with higher expression of ventricular myosin heavy chain ( vmhc ) and insulin like-growth factor ( igf ). These hearts displayed a more mature muscle striation pattern with larger,fewer cardiomyocytes, greater ventricle stroke volume and cardiac output compared to controls. Adult hearts (120 days) derived from Dex-treated embryos were heavier (corrected for total body weight 1.02 ± 0.07 µg/mg vs controls 0.63 ± 0.06 µg/mg, p = 0.0007) with increased vmhc mRNA compared to controls. In contrast, GR knockdown with morpholino resulted in smaller hearts with fewer cardiomyocytes, less mature striation pattern, reduced cardiac function and reduced levels of vmhc and igf mRNA in ZFe compared to controls. Adult hearts derived from GR MO embryos were smaller with reduced myocardium wall thickness and increased ventricular cavity area (20.32 ± 1.24% vs controls 11.89 ± 1.22%, p < 0.001) with reduced expression of vmhc . Echocardiography of adult hearts revealed altered Doppler ventricle-inflow patterns in GR Mo but not Dex adults. Conclusions Short-term alterations in GR activity during embryonic development result in altered structure, function and molecular signalling in the heart with effects maintained into adulthood. These findings point to a mechanism by which foetal GC induced reprogramming could influence reprogramming could influence susceptibility to adult disease.

Corneal tissue interactions of a new 345 nm ultraviolet femtosecond laser

To assess the suitability of a new 345 nm ultraviolet (UV) femtosecond laser for refractive surgery. Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany. Experimental study. Twenty-five porcine corneas were used for stromal flap or lamellar bed creation (stromal depth, 150 μm) and 15 rabbit corneas for lamellar bed creation near the endothelium. Ultraviolet femtosecond laser cutting-line morphology, gas formation, and keratocyte death rate were evaluated using light and electron microscopy and compared with a standard infrared (IR) femtosecond laser. Endothelial cell survival was examined after application of a laser cut near the endothelium. Flaps created by the UV laser were lifted easily. Gas formation was reduced 4.2-fold compared with the IR laser (P = .001). The keratocyte death rate near the interface was almost doubled; however, the death zone was confined to a region within 38 μm ± 10 (SD) along the cutting line. Histologically and ultrastructurally, a distinct and continuous cutting line was not found after UV femtosecond laser application if flap lifting was omitted and standard energy parameters were used. Instead, a regular pattern of vertical striations, presumably representing self-focusing induced regions of optical tissue breakdown, were identified. Lamellar bed creation with standard energy parameters 50 μm from the endothelium rendered the endothelial cells intact and viable. The new 345 nm femtosecond laser is a candidate for pending in vivo trials and future high-precision flap creation, intrastromal lenticule extraction, and ultrathin Descemet-stripping endothelial keratoplasty. Mr. Klenke and Ms. Skerl were paid employees of Wavelight GmbH when the study was performed. Dr. Seiler is a scientific consultant to Wavelight GmbH. No other author has a financial or proprietary interest in any material or method mentioned.