560 research outputs found

    On Fejér Type Inequalities For Products Two Convex Functions

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    In this paper, we first obtain some new Fejér type inequalities for products of two convex mappings. Moreover, by applying these inequalities for Riemann-Liouville fractional integrals, we establish some Fejér type inequalities involving Riemann-Liouville fractional integrals. The most important feature of our work is that it contains Fejér type inequalities for both classical integrals and fractional integrals

    Turfgrass species response exposed to increasing rates of glyphosate application

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    To investigate the response of nine turfgrass species exposed to increasing rates of glyphosate application, the dry matter production, visual leaf injury symptoms (e.g., chlorosis and necrosis) and the concentrations of shikimate and mineral nutrients were determined in shoots. The rates of foliar glyphosate application were 0%, 5% (1.58 mM), and 20% (6.32mM) of the recommended application rate for weed control. In general, there was a negative and weak correlation between the intensity of visual injury and relative decreases in shoot dry matter production caused by glyphosate application. The decreases in shoot dry matter production and the severity of leaf damage pronounced by increasing glyphosate rate showed a substantial variation among the turfgrass species. Of the turfgrass species tested, Festuca arundinacea ‘Falcon’ and Buchloe dactyloides ‘Bowie’were selected as the most tolerant and sensitive species to applied sublethal rates of glyphosate as judged from visual injury ratings, respectively. At the highest glyphosate rate, shoot dryweightwas decreased by 4-fold in Bowie and only 1.6-fold in Falcon. When glyphosatewas not applied, shoot shikimate concentration of all species was very low and below 2.8mol g−1 FW (fresh weight). Glyphosate applications resulted in increases in shoot shikimate concentration with substantial variations among species. At 6.32mM glyphosate treatment, shikimate concentration ranged between 156.1mol g−1 (F. rubra, Ambrose) and 16.5mol g−1 FW (F. rubra, Cindy Lou). However, the highly sensitive and the tolerant genotypes were not different in shoot shikimate concentrations. Even, in the case of some genotypes, high glyphosate tolerance is accompanied by higher shoot concentrations of shikimate. Depending on the turfgrass species and mineral nutrients tested, increasing glyphosate application either did not affect or reduced mineral nutrient concentrations. In the case of decreases in shoot concentration of mineral nutrients, the decreases in Ca, Mg, Mn and Fe were most distinct. The results obtained indicate existence of a large genetic variation in tolerance to glyphosate toxicity among the turfgrass species. This differential variation in tolerance to glyphosate could not be explained by the changes in shoot concentrations of shikimate and mineral nutrients

    Cyclohexenones Through Addition of Ethyl Acetoacetate to 3-Aryl-1-(thiophen-3-yl)prop-2-en-1-one Derivatives

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    Chalcone derivatives 3a–i containing a thiophene ring were prepared by the condensation of 1-(thiophen-3-yl)ethanone with aromatic aldehydes in excellent yields. The Michael addition of ethyl acetoacetate 4 to chalcone derivatives 3a–i resulted in the formation of nine novel ethyl 6-aryl 4-(3-thienyl)cyclohex-3-en-2-one-1-carboxylate derivatives 6a–i.Keywords: Michael Addition, Ethyl Acetoacetate, Cyclohexenones, Cyclocondensatio

    An experimental investigation of chatter effects on tool life

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    Tool wear is one of the most important considerations in machining operations as it affects surface quality and integrity, productivity and cost. The most commonly used model for tool life analysis is the one proposed by F.W. Taylor about a century ago. Although the extended form of this equation includes the effects of important cutting conditions on tool wear, tool life studies are mostly performed under stable cutting conditions where the effect of chatter vibrations are not considered. This paper presents an empirical attempt to understand tool life under vibratory cutting conditions. Tool wear data are collected in turning and milling on different work materials under stable and chatter conditions. The effects of cutting conditions as well as severity of chatter on tool life are analyzed. The results indicate significant reduction in tool life due to chatter as expected. They also show that the severity of chatter, and thus the vibration amplitude, strongly reduces the life of cutting tools. These results can be useful in evaluating the real cost of chatter by including the reduced tool life. They can also be useful in justifying the cost of chatter suppression and more rigid machining systems

    The role of tool geometry in process damped milling

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    The complex interaction between machining structural systems and the cutting process results in machining instability, so called chatter. In some milling scenarios, process damping is a useful phenomenon that can be exploited to mitigate chatter and hence improve productivity. In the present study, experiments are performed to evaluate the performance of process damped milling considering different tool geometries (edge radius, rake and relief angles and variable helix/pitch). The results clearly indicate that variable helix/pitch angles most significantly increase process damping performance. Additionally, increased cutting edge radius moderately improves process damping performance, while rake and relief angles have a smaller and closely coupled effect

    Tool path pattern and feed direction selection in robotic milling for increased chatter-free material removal rate

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    Robotic milling becomes increasingly relevant to large-scale part manufacturing industries thanks to its cost-effective and portable manufacturing concept compared to large-scale CNC machine tools. Integration of milling processes with industrial robots is proposed to be well aligned with the aims and objective of the recent fourth industrial revolution. However, the industrial robots introduce position-dependent and asymmetrical dynamic flexibility, which may reflect to the tool tip dynamics under several conditions. Under such circumstances, the stability limits become dependent on the machining location and the feed direction. In this respect, selection of machining tool path patterns is crucial for increased chatter-free material removal rates (MRR). This paper proposes an approach to evaluate and select tool path patterns, offered by the existing CAM packages, for increased chatter-free MRR. The machining area is divided into number of machining locations. The optimal feed direction is decided based on the absolute stability at each region considering the asymmetrical and position-dependent tool tip dynamics. Then, the alternative tool path patterns are evaluated and the corresponding optimum feed direction is decided for increased chatter-free material removal. The application of the proposed approach is demonstrated through simulations and representative experiments

    Unique and conserved MicroRNAs in wheat chromosome 5D revealed by next-generation sequencing

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    MicroRNAs are a class of short, non-coding, single-stranded RNAs that act as post-transcriptional regulators in gene expression. miRNA analysis of Triticum aestivum chromosome 5D was performed on 454 GS FLX Titanium sequences of flow sorted chromosome 5D with a total of 3,208,630 good quality reads representing 1.34x and 1.61x coverage of the short (5DS) and long (5DL) arms of the chromosome respectively. In silico and structural analyses revealed a total of 55 miRNAs; 48 and 42 miRNAs were found to be present on 5DL and 5DS respectively, of which 35 were common to both chromosome arms, while 13 miRNAs were specific to 5DL and 7 miRNAs were specific to 5DS. In total, 14 of the predicted miRNAs were identified in wheat for the first time. Representation (the copy number of each miRNA) was also found to be higher in 5DL (1,949) compared to 5DS (1,191). Targets were predicted for each miRNA, while expression analysis gave evidence of expression for 6 out of 55 miRNAs. Occurrences of the same miRNAs were also found in Brachypodium distachyon and Oryza sativa genome sequences to identify syntenic miRNA coding sequences. Based on this analysis, two other miRNAs: miR1133 and miR167 were detected in B. distachyon syntenic region of wheat 5DS. Five of the predicted miRNA coding regions (miR6220, miR5070, miR169, miR5085, miR2118) were experimentally verified to be located to the 5D chromosome and three of them : miR2118, miR169 and miR5085, were shown to be 5D specific. Furthermore miR2118 was shown to be expressed in Chinese Spring adult leaves. miRNA genes identified in this study will expand our understanding of gene regulation in bread wheat

    On the stability of high-speed milling with spindle speed variation

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    Spindle speed variation is a well-known technique to suppress regenerative machine tool vibrations, but it is usually considered to be effective only for low spindle speeds. In this paper, the effect of spindle speed variation is analyzed in the high-speed domain for spindle speeds corresponding to the first flip (period doubling) and to the first Hopf lobes. The optimal amplitudes and frequencies of the speed modulations are computed using the semidiscre- tization method. It is shown that period doubling chatter can effectively be suppressed by spindle speed variation, although, the technique is not effective for the quasiperiodic chatter above the Hopf lobe. The results are verified by cutting tests. Some special cases are also discussed where the practical behavior of the system differs from the predicted one in some ways. For these cases, it is pointed out that the concept of stability is understood on the scale of the principal period of the system—that is, the speed modulation period for variable spindle speed machining and the tooth passing period for constant spindle speed machining

    A microsatellite marker for yellow rust resistance in wheat

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    Bulk segregant analysis (BSA) was used to identify molecular markers associated with yellow rust disease resistance in wheat (Triticum aestivum L.). DNAs isolated from the selected yellow rust tolerant and susceptible F-2 individuals derived from a cross between yellow rust resistant and susceptible wheat genotypes were used to established a "tolerant" and a "susceptible" DNA pool. The BSA was then performed on these DNA pools using 230 markers that were previously mapped onto the individual wheat chromosomes. One of the SSR markers (Xgwm382) located on chromosome group 2 (A, B, D genomes) was present in the resistant parent and the resistant bulk but not in the susceptible parent and the susceptible bulk, suggesting that this marker is linked to a yellow rust resistance gene. The presence of Xgwm382 was also tested in 108 additional wheat genotypes differing in yellow rust resistance. This analysis showed that 81% of the wheat genotypes known to be yellow rust resistant had the Xgwm382 marker, further suggesting that the presence of this marker correlates with yellow rust resistance in diverse wheat germplasm. Therefore, Xgwm382 could be useful for marker assisted selection of yellow rust resistances genotypes in wheat breeding programs

    Zeta potential: A surface electrical characteristic to probe the interaction of nanoparticles with normal and cancer human breast epithelial cells

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    We demonstrate the use of surface Zeta potential measurements as a new tool to investigate the interactions of iron oxide nanoparticles and cowpea mosaic virus (CPMV) nanoparticles with human normal breast epithelial cells (MCF10A) and cancer breast epithelial cells (MCF7) respectively. A substantial understanding in the interaction of nanoparticles with normal and cancer cells in vitro will enable the capabilities of improving diagnostic and treatment methods in cancer research, such as imaging and targeted drug delivery. A theoretical Zeta potential model is first established to show the effects of binding process and internalization process during the nanoparticle uptake by cells and the possible trends of Zeta potential change is predicted for different cell endocytosis capacities. The corresponding changes of total surface charge of cells in the form of Zeta potential measurements were then reported after incubated respectively with iron oxide nanoparticles and CPMV nanoparticles. As observed, after MCF7 and MCF10A cells were incubated respectively with two types of nanoparticles, the significant differences in their surface charge change indicate the potential role of Zeta potential as a valuable biological signature in studying the cellular interaction of nanoparticles, as well as specific cell functionality. © Springer Science+Business Media, LLC 2007
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