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On the composition of microtwins in a single crystal nickel-based superalloy
No full textAbstractCorrelative analysis is performed using atom probe tomography and high resolution transmission Kikuchi diffraction techniques on microtwins of ∼10nm thickness, in a ⟨011⟩-orientated single crystal superalloy crept at 800°C and 650MPa. Composition profiles across the microtwins and microtwin-parent boundaries are presented. Enrichment of microtwin-parent interfaces by approximately 2at.% Cr and 1at.% Co within the γ′-phase is found; no compositional variations of other elements – Ta, Nb, Mo, W – are detected. Our results provide unique insights into the mechanism of microtwin formation and the likely influence of alloy composition on deformation kinetics
Time-resolved imaging of flyer dynamics for femtosecond laser-induced backward transfer of solid polymer thin films
No full textAbstractWe have studied the transfer regimes and dynamics of polymer flyers from laser-induced backward transfer (LIBT) via time-resolved shadowgraphy. Imaging of the flyer ejection phase of LIBT of 3.8μm and 6.4μm thick SU-8 polymer films on germanium and silicon carrier substrates was performed over a time delay range of 1.4–16.4μs after arrival of the laser pulse. The experiments were carried out with 150fs, 800nm pulses spatially shaped using a digital micromirror device, and laser fluences of up to 3.5J/cm2 while images were recorded via a CCD camera and a spark discharge lamp. Velocities of flyers found in the range of 6–20m/s, and the intact and fragmented ejection regimes, were a function of donor thickness, carrier and laser fluence. The crater profile of the donor after transfer and the resulting flyer profile indicated different flyer ejection modes for Si carriers and high fluences. The results contribute to better understanding of the LIBT process, and help to determine experimental parameters for successful LIBT of intact deposits
Free radical scavenging activity, kinetic behaviour and phytochemical constituents of Aristolochia clematitis L. roots
No full textAbstractNowadays there is an increasing demand of natural antioxidants. Imbalanced production and consumption of reactive oxygen species, lead to many diseases such as cancer, arteriosclerosis and ageing processes. The protective effects of plants have long been attributed to their antioxidant compounds, like polyphenols, flavonoids, carotenoids, and vitamins C and E. Therefore, the present study was designed to evaluate the antioxidant activity of tannins and crude methanolic extracts of Aristolochia clematitis L. by two complementary test systems (DPPH free radical scavenging and bioautography HPTLC). Besides, phytochemical screening was carried out on roots of A. clematitis and showed the presence of tannins, alkaloids and essential oils.High performance thin layer chromatography (HPTLC) screening provided qualitatively the antioxidant effect of extracts under study. Furthermore, it was found that the tannins and methanolic crude extracts from A. clematitis had a potent DPPH scavenging potency with IC50 values of 0.196 and 0.142mg/mL, respectively. Besides, the kinetic behaviour of DPPH radical scavenging activity of extracts under study allowed us to determine the half life t1/2, time reaction (t) and the remaining DPPH percent
Datasets for testing the performances of jump diffusion models
No full textAbstractThis article contains datasets related to the research article titled a novel jump diffusion model based on SGT distribution and its applications (”A novel jump diffusion model based on SGT distribution and its applications” (W.J. Xu, G.F. Liu, H.Y. Li, 2016) [1]). The datasets contain continuous composite daily percentage return values which are computed from the daily closing prices. Firstly, we describe statistical properties of the datasets. Then, the datasets are split into two samples, the in-sample data and out-of-sample data. The datasets can be used as benchmarks for testing the performances of jump diffusion models
Deformation and fracture of echinoderm collagen networks
No full textAbstractCollagen networks provide the main structural component of most tissues and represent an important ingredient for bio-mimetic materials for bio-medical applications. Here we study the mechanical properties of stiff collagen networks derived from three different echinoderms and show that they exhibit non-linear stiffening followed by brittle fracture. The disordered nature of the network leads to strong sample-to-sample fluctuations in elasticity and fracture strength. We perform numerical simulations of a three dimensional model for the deformation of a cross-linked elastic fibril network which is able to reproduce the macroscopic features of the experimental results and provide insights into the internal mechanics of stiff collagen networks. Our numerical model provides an avenue for the design of collagen membranes with tunable mechanical properties
Deformation mechanisms in nanoporous metals: Effect of ligament shape and disorder
No full textAbstractThe current work presents a numerical modelling approach for investigating the effect of ligament shape and disorder on the macroscopic mechanical response of nanoporous gold (NPG). The approach starts from a ‘single ligament’ analysis with respect to three fundamental deformation modes, bending, torsion, and compression, that depend on the ligament shape. It can be shown that the predictive capability of the highly computationally efficient beam model is sufficient for a large variation in ligament shapes. Using a representative volume element (RVE) composed of such ligaments, different degrees of disorder are included. For both the single ligament and RVE models, the cylindrical beam serves as a common reference to compare the results when varying the ligament shape. From the comparison of the RVE elastic response with the single ligament results and the further analysis of statistical information from the elements in the RVE, it is found that bending is the major deformation mode for perfectly ordered RVEs, whereas torsion gains importance for increasing RVE disorder. The effect of compression of the ligaments can be neglected in general. It is concluded that the transition to torsion deformation due to disorder is the cause of the strongly reduced lateral expansion during compression deformation of NPG
Lesser Prairie-Chicken Avoidance of Trees in a Grassland Landscape
No full textAbstractGrasslands are among the most imperiled ecosystems in North America. Reasons that grasslands are threatened include conversion to row-crop agriculture, fragmentation, and changes in fire regimes. The reduction of fire processes in remaining prairies has resulted in tree encroachment and establishment in grasslands, further reducing grassland quantity and quality. Grassland birds have been experiencing precipitous population declines in recent decades, commensurate with landscape changes to grasslands. The lesser prairie-chicken (Tympanuchus pallidicinctus Ridgway) is a declining species of prairie grouse of conservation concern. We used second- and third-order habitat selection metrics to test if female lesser prairie-chickens avoid grasslands where trees were present. Our results indicated that female lesser prairie-chickens selected habitats avoiding the nearest trees by 283 m on average, nearly twice as far as would be expected at random. Lesser prairie-chickens were 40 times more likely to use habitats with tree densities of 0 trees ∙ ha−1 than habitats with 5 trees ∙ ha−1. Probability of use indicated that lesser prairie-chickens were 19 times more likely to use habitats 1000 m from the nearest tree when compared with using habitats 0 m from the nearest tree. Nest survival was not affected at densities < 2 trees ∙ ha−1; however, we could not test if nest survival was affected at greater tree densities as no nests were detected at densities > 2 trees ∙ ha−1. Avoidance of trees could be due to perceived increased predation risk, reduced habitat quality, or a combination of these potentially confounding factors. Preventing further establishment and expansion of trees in landscapes occupied by lesser prairie-chickens could contribute to the continued persistence of the species. Additionally, restoring grasslands through tree removal may facilitate conservation efforts for grassland species such as the lesser prairie-chicken by improving habitat quality and promoting expansion of occupied range
Bryophytes: Hoard of remedies, an ethno-medicinal review
No full textAbstractBryophytes are the second largest group of land plants after angiosperms. There is very less knowledge available about medicinal properties of these plants. Bryophytes are popular remedy among the tribal people of different parts of the world. Tribal people use these plants to cure various ailments in their daily lives. Bryophytes are used to cure hepatic disorders, skin diseases, cardiovascular diseases, used as antipyretic, antimicrobial, wound healing and many more other ailments by different tribal communities of Africa, America, Europe, Poland, Argentina, Australia, New Zealand, Turkey, Japan, Taiwan, Pakistan, China, Nepal and different parts of South, North and Eastern India. Apart from ethno-medicinal uses some bryophytes possesses antitumor activities against different cancer cell lines and this property of bryophytes needs to be more focused in the future. Compile information about medicinal properties and anticancer properties of bryophytes is lacking till date. In the present review, the authors tried to compile all the ethno-medicinal and other related information of bryophytes and fill the knowledge lacuna in this particular field. Some published reviews are available but the information is segregated. This manuscript will help people doing research in the bryophytes
Prevalence and clinical features of Fabry disease in Japanese male patients with diagnosis of hypertrophic cardiomyopathy
No full textAbstractBackgroundThe prevalence of Fabry disease (FD) in Japanese patients presenting with unexplained left ventricular hypertrophy (LVH) has remained unclear.MethodsWe measured plasma α-galactosidase A activity in 177 men with a diagnosis of hypertrophic cardiomyopathy (HCM) (maximum LV wall thickness ≥15mm).ResultsTwo patients (1.1%) showed very low α-galactosidase A activity [0.0 and 0.3nmol/hr/ml (normal range: 3.6–17.6nmol/hr/ml)], and a clinical diagnosis of cardiac variant of FD was finally made. One patient was a 55-year-old man who came to our hospital because of abnormal results of electrocardiography and showed concentric LVH in echocardiography. A missense mutation, R112L, was identified. The other was a 74-year-old man who had been diagnosed with HCM at the age of 60 years in another hospital and was referred for evaluation of repeated hospitalization for heart failure. Although echocardiography revealed asymmetric septal hypertrophy (ASH) with interventricular septal wall thickness of 16mm and posterior wall thickness of 11mm and reduced LV ejection fraction with hypokinetic posterior wall motion, his echocardiographic findings at the initial diagnosis of HCM were not ASH but concentric LVH with normal LV systolic function. A splicing mutation, IVS4+919G>A, was identified.ConclusionsThe prevalence of FD in Japanese male patients with a clinical diagnosis of HCM was found to be 1.1%. These patients showed late onset and concentric LVH at initial presentation
Identification of Stem Cells in the Epithelium of the Stomach Corpus and Antrum of Mice
No full textBackground & AimsLittle is known about the mechanisms of gastric carcinogenesis, partly because it has been a challenge to identify characterize gastric stem cells. Runx genes regulate development and their products are transcription factors associated with cancer development. A Runx1 enhancer element, eR1, is a marker of hematopoietic stem cells. We studied expression from eR1 in the stomach and the roles of gastric stem cells in gastric carcinogenesis in transgenic mice.MethodsWe used in situ hybridization and immunofluorescence analyses to study expression of Runx1 in gastric tissues from C57BL/6 (control) mice. We then created mice that expressed enhanced green fluorescent protein (EGFP) or CreERT2 under the control of eR1 (eR1-CreERT2;Rosa-Lox-Stop-Lox [LSL]-tdTomato, eR1-CreERT2;Rosa-LSL-EYFP mice). Gastric tissues were collected and lineage-tracing experiments were performed. Gastric organoids were cultured from eR1-CreERT2(5-2);Rosa-LSL-tdTomato mice and immunofluorescence analyses were performed. We investigated the effects of expressing oncogenic mutations in stem cells under control of eR1 using eR1-CreERT2;LSL-KrasG12D/+ mice; gastric tissues were collected and analyzed by histology and immunofluorescence.ResultsMost proliferation occurred in the isthmus; 86% of proliferating cells were RUNX1-positive and 76% were MUC5AC-positive. In eR1-EGFP mice, EGFP signals were detected mainly in the upper part of the gastric unit, and 83% of EGFP-positive cells were located in the isthmus/pit region. We found that eR1 marked undifferentiated stem cells in the isthmus and a smaller number of terminally differentiated chief cells at the base. eR1 also marked cells in the pyloric gland in the antrum. Lineage-tracing experiments demonstrated that stem cells in the isthmus and antrum continuously gave rise to mature cells to maintain the gastric unit. eR1-positive cells in the isthmus and pyloric gland generated organoid cultures in vitro. In eR1-CreERT2;LSL-Kras G12D/+ mice, MUC5AC-positive cells rapidly differentiated from stem cells in the isthmus, resulting in distinct metaplastic lesions similar to that observed in human gastric atrophy.ConclusionsUsing lineage-tracing experiments in mice, we found that a Runx1 enhancer element, eR1, promotes its expression in the isthmus stem cells of stomach corpus as well as pyloric gland in the antrum. We were able to use eR1 to express oncogenic mutations in gastric stem cells, proving a new model for studies of gastric carcinogenesis