jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Manuel Rivas
Source: OpenCommons - UConn (University of Connecticut) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Iridium Oxide (IrO2) as a Top Electrode for Ferroelectric Micro-Electro-Mechanical Systems (MEMS) Devices for Radiation Rich Environments The multifunctional properties of ferroelectric materials make them ideal components for numerous applications including for extreme environments such as space. Iridium oxide (IrO2) electrodes have been demonstrated to improve the lifetime of ferroelectric memory devices, however little is known about its influence on the electromechanical properties important for ferroelectric microelectromechanical systems (MEMS). The performance of thin film lead zirconate titanate (PZT) based MEMS is affected by the processing conditions, composition, device design, electrode materials, and the environment. This work details the development and characterization of iridium oxide electrodes for PZT based microelectromechanical and pyroelectric-harvesting systems, fabrication induced defects, and design of clamped vs unclamped devices. This work also considers the influence of iridium oxide top electrodes on the properties of PZT films and MEMS devices subjected to gamma and heavy ion radiation for applications in space and for evaluating nuclear material where human exposure must be kept to a minimum.\nUsing single point force measurements with an atomic force microscope, this work presents the first known experimental value of Young’s modulus for thin film IrO2 (𝐸𝐸𝐼𝐼𝐼𝐼𝐼𝐼2 = 262 GPa). It was discovered that iridium oxide films of different morphologies are produced by manipulating the reactive gas flow rate in a sputtering process. Planar IrO2 for piezoelectric applications was optimized at 60 sccm O2 flow rate deposited at 500°C. Nanostructured, 2D platelets are observed for high oxygen flow rates (100 sccm) producing a self-limiting dense columnar film as the base of the plate-like structures. While the plate-like region continues to grow with increased deposition at a rate of ~6 nm/s, the dense film appears to reach a critical thickness of approximately 60 ± 10. Devices with iridium oxide top electrode appear to be more radiation resistant when compared to identically fabricated devices with a platinum (Pt) top electrode, when exposed up to 10 Mrad(Si) of gamma rays from a 60Co source and an equivalent dose with Fe3+ ions. Microelectromechanical systems ; Ferroelectricity ; Iridium ; Materials science ; Electrode ; Optoelectronics ; Oxide ; Nanotechnology ; Metallurgy ; Chemistry Ferroelectric and Piezoelectric Materials ; Acoustic Wave Resonator Technologies ; Advanced MEMS and NEMS Technologies
Authors: J. M. De Sousa | Marcelo G. Vivas | Jefferson Luís Ferrari | Marco Antônio Schiavon
Source: Journal of the Brazilian Chemical Society (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Synthesis and Optical Properties of Water-Soluble CdTe:Zn2+ Quantum Dots Prepared by the One-Pot Approach This paper reports the synthesis and characterization of ternary CdTe:Zn 2+ quantum dots (QDs) passivated with reduced L-glutathione (GSH) dispersed in water. The synthesis was performed through a one-pot approach and their size-dependent optical properties were investigated through steady-state absorption and emission spectroscopies along with the evolving factor analysis/ multivariate curve resolution alternating least squares (EFA/MCR-ALS) method. Our results show that the incorporation of Zn 2+ ions in CdTe:Zn 2+ QDs, during the synthesis time, decreases the CdTe:Zn 2+ QDs predominant diameter in the ensemble and increases their size dispersion. In addition, fluorescence quantum yield measurements suggest a reduction in the number of surface defects in CdTe:Zn 2+ QDs as compared with CdTe QDs, when both are produced from the same synthesis route. Cadmium telluride photovoltaics ; Quantum dot ; Water soluble ; Nanotechnology ; Chemistry ; Chemical engineering ; Materials science ; Organic chemistry ; Engineering Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films ; Nonlinear Optical Materials Research
Authors: Juan García de la Concepción | Martı́n Ávalos | Pedro Cintas | José L. Jiménez | Mark E. Light
Source: Organic & Biomolecular Chemistry (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

On the dual reactivity of a Janus-type mesoionic dipole: experiments and theoretical validation A mesoionic bicycle, easily synthesized from a proteinogenic amino acid, l-leucine, behaves as both thiazolium-olate and diazolium-olate dipoles, as unveiled by its dipolar cycloadditions. This chameleonic reactivity has been thoroughly interpreted by dissecting the mechanistic landscape aided by the distortion-interaction model. Mesoionic ; Chemistry ; Janus ; Reactivity (psychology) ; Dipole ; Dual (grammatical number) ; Combinatorial chemistry ; Computational chemistry ; Nanotechnology ; Organic chemistry Porphyrin and Phthalocyanine Chemistry ; Polyoxometalates: Synthesis and Applications ; Cyclopropane Reaction Mechanisms
Authors: Han Sang Oh | Sung‐Eun Lee | Chae-seong Han | Joon Kim | Onyou Nam | Seungbeom Seo | Kwang Suk Chang | EonSeon Jin | Yong‐sic Hwang
Source: ALGAE (article, 2018-06-14)
Field: Materials Science — Biomaterials

Silicon transporter genes of Fragilariopsis cylindrus (Bacillariophyceae) are differentially expressed during the progression of cell cycle synchronized by Si or light Fragilariopsis cylindrus is one of the most successful psychrophiles in the Southern Ocean. To investigate the molecular mechanism of biomineralization in this species, we attempted to synchronize F. cylindrus growth, since new cell wall formation is tightly coupled to the cell division process. Nutrient limitation analysis showed that F. cylindrus cultures rapidly stopped growing when deprived of silicate or light, while growth continued to a certain extent in the absence of nitrate. Flow cytometry analysis indicated that deprivation of either silicate or light could effectively arrest the cell cycle of this diatom species at the G1 phase, suggesting that synchrony can be established using either factor. Fluorescence labeling of new cell walls was faintly detectable as early as approximately 6 h after silicon repletion or light irradiation, and labeling was markedly intensified by 18 h. It is revealed that the synthesis of girdle bands begins before valve synthesis in this species, with active valve synthesis occurring during the G2 / M phase. Expression profiling revealed that selective member(s) of the F. cylindrus SIT genes (FcSIT) respond to silicate and light, with a different set of genes being responsive to each factor. The Si / light double depletion experiments demonstrated that expression of one FcSIT gene is possibly correlated to transition to G2 / M phase of the cell cycle, when the valve is actively formed. Diatom ; Cell cycle ; Biology ; Cell division ; Silicate ; Cell biology ; Psychrophile ; Transcriptome ; Biochemistry ; Gene ; Biophysics ; Chemistry ; Gene expression ; Cell ; Botany ; Enzyme Diatoms and Algae Research ; Protist diversity and phylogeny ; Marine and coastal ecosystems
Authors: Heng-Ling Meng | Wei Zhang | Guanghui Zhang | Jianjun Wang | Zhen-Gui Meng | G. Long | Sheng-Chao Yang
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-08-13)
Field: Materials Science — Biomaterials

Unigene-based RNA-seq provides insights on drought stress responses in <i>Marsdenia tenacissima</i> Abstract Marsdenia tenacissima is a well-known anti-cancer medicinal plant used in traditional Chinese medicine. Drought severely affects production and no information on its transcriptional responses to drought stress is available. In this study, cDNA libraries on control (CK), drought stress (T1), and re-watering (T2) treatments were constructed and HiSeq 2000 sequencing was performed using the Illumina platform. There were 43,129,228, 47,116,844, and 42,815,454 clean reads with Q20 values of 98.06, 98.04, and 97.88, respectively. A total of 8672, 6043, and 6537 differentially expressed genes (DEGs) were identified when CK vs. T1, CK vs. T2, and T1 vs. T2, respectively, were analyzed. In addition, 1039, 1016, and 980 transcription factors (TFs) were identified in CK, T1, and T2, respectively. Among them, 363, 267, and 299 TFs were identified as DEGs in CK vs. T1, CK vs. T2, and T1 vs. T2, respectively. These differentially expressed TFs mainly belonged to the bHLH, bZIP, C2H2, ERF, MYB, MYB-related, and NAC families. A comparative analysis of CK vs. T1 and T1 vs. T2 found that 1174 genes were up-regulated and 2344 were down-regulated under drought stress and this pattern was the opposite to that found after re-watering. Among the 1174 genes up-regulated by drought stress, 64 were homologous to known functional genes that directly protect plants against drought stress. Furthermore, 44 protein kinases and 38 TFs with opposite expression patterns under drought stress and re-watering were identified, which are possibly candidate regulators for drought stress resistance in M. tenacissima . Our study is the first to characterize the M. tenacissima transcriptome in response to drought stress, and will serve as a useful resource for future studies on the functions of candidate protein kinases and TFs involved in M. tenacissima drought stress resistance. UniGene ; MYB ; Gene ; Biology ; Drought stress ; RNA-Seq ; Transcription factor ; Genetics ; Gene expression ; Transcriptome ; Botany Phytochemistry and Bioactive Compounds ; Plant Molecular Biology Research ; Plant Stress Responses and Tolerance
Authors: Borja Erice | Daniel Thomson | Sathiskumar A. Ponnusami | M.V. Pathan | Nik Petrinić
Source: EPJ Web of Conferences (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

On the Rate-dependent Plasticity Modelling of Unidirectional Fibre-reinforced Polymeric Matrix Composites Three different approaches to plasticity are investigated to model the experimentally-observed non-linear behaviour of unidirectional fibre-reinforced polymeric matrix materials. The first and simplest approach consists on assuming independent one-dimensional rate-dependent plasticity on in-plane (12) and through-thickness longitudinal (13) shear components of the Cauchy stress tensor. The second, employs a 3D extension of the plane stress Hill’48 anisotropic plastic surface. The third and the last is formulated as a quadratic yield function inspired by Puck’s fracture initiation criterion. It searches for a plastic localisation plane in which a certain combination of normal and shear stresses is maximum. Numerical simulations are conducted to analyse the off-axis compression behaviour of carbon fibre reinforced epoxy composite under varying loading rates. The afore-mentioned three different approaches are explored with an aim to predict the experimentally-observed non-linear response of such composites. The model parameters are determined using a deterministic inverse modelling strategy employing an iterative domain reduction optimisation technique. As far as the experiments are concerned, the quasi-static and medium rate tests were carried out in universal testing machines, while the experiments at high rate were conducted in a Split Hopkinson Pressure Bar system. The effectiveness in terms of accuracy and robustness of the three approaches are discussed. Materials science ; Composite material ; Plasticity ; Epoxy ; Anisotropy ; Plane stress ; Cauchy distribution ; Mathematics ; Structural engineering ; Mathematical analysis ; Finite element method ; Physics High-Velocity Impact and Material Behavior ; Mechanical Behavior of Composites ; Structural Response to Dynamic Loads
Authors: Trevor K. Decker | Ya‐Jun Zheng | Joshua S. McClellan | Aaron J. Ruben | Stephen A. Lammert | Daniel E. Austin | Aaron R. Hawkins
Source: Rapid Communications in Mass Spectrometry (article, 2018-08-22)
Field: Chemistry — Spectroscopy

Double resonance ejection using novel radiofrequency phase tracking circuitry in a miniaturized planar linear ion trap mass spectrometer The phase tracking circuitry proved effective despite deviations from a true phase locked condition. Double resonance ejection is a means to increase signal intensity in a miniaturized planar ion trap. Chemistry ; Miniaturization ; Resonance (particle physics) ; Ion trap ; Quadrupole ion trap ; Planar ; Ion ; Mass spectrometry ; Tracking (education) ; SIGNAL (programming language) ; Nuclear magnetic resonance ; Analytical Chemistry (journal) ; Atomic physics ; Physics ; Materials science ; Nanotechnology Mass Spectrometry Techniques and Applications ; Pesticide Residue Analysis and Safety ; Analytical Chemistry and Chromatography
Authors: Marcus Portelli | A. Bertarelli | Federico Carra | Linus K. Mettler | Pierluigi Mollicone | Nicholas Sammut
Source: Physical Review Accelerators and Beams (article, 2018-06-25)
Field: Materials Science — Materials Chemistry

Numerical simulation of long rods impacted by particle beams Analytical solutions detailing the propagation of longitudinal waves in slender rods subjected to a sudden increase of internal energy provide simple tools for the calculation of the temperature distribution in impacted rods as well as the resulting mechanical response. The topic is of great interest in particle accelerator technology, especially with regards to collimation systems, where beam intercepting devices can be generally approximated to one-dimensional (1D) elements potentially subjected, in accidental scenarios, to abrupt thermal energy depositions induced by the impacting particles. In this study, two finite element numerical models are presented and compared to the analytical solutions by Bertarelli, Dallocchio and Kurtyka, discussing the rapid temperature increase in slender rods due to particle beam impacts and the resulting dynamic longitudinal response. The first model is a sequentially coupled thermomechanical analysis; the second is based on a modal analysis to find the harmonic response of the system. The results indicate that phenomena neglected in analytical solutions, primarily dispersion of the longitudinal wave due to interactions with the free external surface of the rod, can be included in numerical models and can be observed in simulation results. The study further shows how numerical methods can be utilized to predict the frequencies and amplitudes of high-frequency disturbances in the longitudinal wave signal, and how these effects can be mitigated in preparation for experimental scenarios by fine-tuning the geometry of the rod and varying the duration of the pulse. This is especially useful with regards to experiments conducted in the HiRadMat facility at CERN, such as the recently conducted HRMT36 experiment, where high-frequency components can distort the signal to be observed. Rod ; Mechanics ; Amplitude ; Finite element method ; Beam (structure) ; Dispersion (optics) ; Harmonic ; Materials science ; Structural engineering ; Physics ; Acoustics ; Optics ; Engineering High-Velocity Impact and Material Behavior ; Laser-Plasma Interactions and Diagnostics ; High-pressure geophysics and materials
Authors: R. Silwal
Source: TigerPrints (Clemson University) (article, 2018-01-01)
Field: Chemistry — Spectroscopy

Extreme ultraviolet spectra of highly charged Y and Xe ions: line identification, diagnostic potential, and isotope shift Highly charged ions have enhanced relativistic eï¬€ects and compressed electronic wave functions, making their atomic transitions relevant in studies of fundamental atomic and nuclear properties. Accurate atomic data such as wavelengths, energy levels, and tran-sition probabilities are vital to the plasma communities. We report the extreme ultraviolet spectroscopy (EUV) of highly charged yttrium and xenon ions that were produced and conï¬ned with an electron beam ion trap (EBIT). The EUV spectra from these ions were recorded with a ï¬‚at-ï¬eld grazing incidence grating spectrometer. In the ﬁrst part of this work, new and previously observed EUV spectral lines were identiﬁed corresponding to the L-shell and a few M-shell yttrium ions (Y26+ – Y36+) in the wavelength range of 4 nm to 20 nm. The wavelength of the Li-like Y resonances, (2s - 2p1/2) and (2s - 2p3/2) and the Na-like D lines in Y, (3s - 3p1/2) and (3s - 3p3/2) were measured with an EBIT for the ﬁrst time. The wavelength uncertainties of the identiﬁed transitions ranged between 0.0004 nm and 0.002 nm. Fifty nine spectral lines corresponding to ∆ n = 0 transitions within the n = 2 and n = 3 shell were identiﬁed. Line identiﬁcation was assisted by the collisional-radiative non-Maxwellian code NOMAD. A few magnetic-dipole lines were measured, and the potential application of these transitions in electron density and temperature diagnostics was analyzed. In the second part of this work, we report a new method based on EUV spectroscopy of Na-like D transitions to measure the variation in mean square charge radii of Xe isotopes. The isotope shift of the Na-like D1 (3s - 3p1/2) transitions between 124Xe and 136Xe isotopes was measured and used to determine this variation by comparison with atomic structure calculations. The calculations were performed using the Relativistic Many-Body Perturba-tion (RMBPT) and Multi-Conï¬guration Dirac-Hartree-Fock (MCDHF) methods that were in excellent agreement with each other. The electron beam energy during the measurement was ï¬xed at 6 keV. The diï¬€erence in the mean-square charge radii, Î´ &lt; r2 &gt; was determined to be 0.269(0.042) fm2, which agrees well with previous measurements and a recommended value reported by [AM13]. The Mg-like (3s2 - 3s3p) transitions were also employed to de-termine the diï¬€erences in the mean square charge radii. Systematic studies of the measured shift were performed, providing conï¬dence in the obtained results. Isotope ; Ion ; Spectral line ; Ultraviolet ; Line (geometry) ; Identification (biology) ; Extreme ultraviolet ; Chemistry ; Physics ; Astrobiology ; Atomic physics ; Astronomy ; Nuclear physics ; Optics ; Biology Mass Spectrometry Techniques and Applications ; Atomic and Molecular Physics ; Isotope Analysis in Ecology
Authors: Tyler Peters
Source: Human Biology (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Methionine Sulfoximine: A Novel Anti Inflammatory Agent ABSTRACT METHIONINE SULFOXIMINE: A NOVEL ANTI-INFLAMMATORY AGENT by TYLER J. PETERS October 2018 Advisor: William Brusilow Major: Biochemistry and Molecular Biology Degree: Doctor of Philosophy The glutamine synthetase inhibitor methionine sulfoximine (MSO), shown previously to prevent death caused by an inflammatory liver response in mice, was tested on in vitro production of cytokines by mouse peritoneal macrophages triggered with lipopolysaccharide (LPS). MSO significantly reduced the production of Interleukin 6 (IL-6) and Tumor Necrosis Factor Alpha (TNFα) at 4 and 6 hours after LPS-treatment. This reduction did not result from decreased transcription of IL-6 and TNFα genes, and therefore appeared to result from post-transcriptional inhibition of synthesis of these cytokines. MSO treatment did not inhibit total protein synthesis and did not reduce the production of a third LPS-triggered cytokine CXCL1, so the effect was not a toxic or global downregulation of the LPS response. The anti-inflammatory effects of a glutamine synthetase inhibitor were seen even though the medium contained abundant (2 mM) glutamine, suggesting that the target for this activity was not glutamine synthetase. In agreement with this hypothesis, the L,R isomer of MSO, which does not inhibit glutamine synthetase and was previously thought to be inert, both significantly reduced IL-6 secretion in isolated macrophages and increased survival in a mouse model for inflammatory liver failure. Our findings provide evidence for a novel target of MSO. Future attempts to identify the additional target would therefore also provide a target for therapies to treat diseases involving damaging cytokine responses. Methionine ; Chemistry ; Medicine ; Pharmacology ; Biochemistry ; Amino acid Synthesis and Catalytic Reactions ; Immune cells in cancer ; Mast cells and histamine
Authors: Lara K. Bogart | Yu. G. Morozov | Ivan P. Parkin | Maksim V. Kuznetcov
Source: Journal of Materials Science Materials in Electronics (article, 2018-07-04)
Field: Materials Science — Materials Chemistry

57Fe Mössbauer study of NiFe2O4 nanoparticles produced by the levitation-jet aerosol technique Levitation ; Spinel ; Aerosol ; Materials science ; Evaporation ; Nanoparticle ; Electric field ; Jet (fluid) ; Helium ; Mössbauer spectroscopy ; Analytical Chemistry (journal) ; Magnetic field ; Nanotechnology ; Mechanics ; Metallurgy ; Magnet ; Atomic physics ; Chemistry ; Thermodynamics ; Meteorology ; Chromatography ; Physics ; Crystallography Magnetic Properties and Synthesis of Ferrites ; Electromagnetic wave absorption materials ; Iron oxide chemistry and applications
Authors: Subhash Nimanpure | S. A. R. Hashmi | Rajnish Kumar | Archana Nigrawal | Hari Narayan Bhargaw | Ajay Naik
Source: Advanced Materials Proceedings (article, 2018-12-01)
Field: Materials Science — Polymers and Plastics

Development of environment friendly electrical insulation from natural fibrils Environment friendly electrical insulation material was developed using bio based rectangular cross sectioned sisal fibrils as reinforcement. High content cellulose base fibrils fibrillated by mechanical disintegration method into macro and micro fibrils from coarse sisal fibre. This fibrils were randomly distributed in polymer matrix. These composites were characterized in term of electrical, mechanical and thermal properties to investigate the stability for high strength electrical insulation materials. Excellent mechanical properties were observed. Tensile, flexural and impact strength of composites at 40 wt. % fibril loading improved by 151.34, 197.43 and 360.07 % as compared to unsaturated polyester resin. A few micro-mechanical models were compared with the experimental values. Nielson-Chen Model predicted the experimental data most accurately. The electrical properties of surface modified sisal fibril composites improved significantly in higher frequency. DSC analysis showed that the decomposition temperature of composite was higher, around 22°C than that of the polyester resin. Thermal degradation reduced and was observed in the range of 83-87% of fibril composites as compared to 97% of resin. Fibril composites are highly sensitive to electrical frequency and exhibit excellent electrical insulation property at 20 kHz. Alkali treated fibril based composites resulted an environment friendly thermally stable, high strength insulation material. Copyright © 2018 VBRI Press. Materials science ; Composite material ; Ultimate tensile strength ; Fibril ; Flexural strength ; Polyester ; Thermal stability ; SISAL ; Composite number ; Cellulose ; Chemical engineering ; Chemistry Natural Fiber Reinforced Composites ; Advanced Sensor and Energy Harvesting Materials