jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Radosław Ł. Gwarda | Tadeusz H. Dzido
Source: Chromatographia (article, 2018-09-01)
Field: Chemistry — Spectroscopy

Correlation of Migration Distance of Peptides in High-Performance Thin-Layer Chromatography and Pressurized Planar Electrochromatography Systems In a series of our previous papers we have investigated the influence of various variables on retention/migration of peptides in various high-performance thin-layer chromatography (HPTLC) and pressurized planar electrochromatography (PPEC) systems. Here we present a correlation of the selectivity of peptide separation in similar, as well as in various HPTLC and PPEC systems investigated before. Our results show that the selectivity in similar HPTLC and PPEC systems is quite different. This results from the share of electrophoresis in separation of solutes by PPEC. The results suggest that combination of HPTLC and PPEC, with properly selected separation conditions (the same, or even better—different for each technique), may be used for efficient two-dimensional separation of peptides. The best separation can be obtained if PPEC is carried out in two opposite directions (toward the cathode and the anode) simultaneously. Electrochromatography ; Chemistry ; Chromatography ; Selectivity ; Planar ; High performance thin layer chromatography ; Thin-layer chromatography ; Capillary electrochromatography ; Electrophoresis ; Analytical Chemistry (journal) ; Stationary phase ; Organic chemistry Analytical Chemistry and Chromatography ; Chromatography in Natural Products ; Mass Spectrometry Techniques and Applications
Authors: Ikuo S. Sogami
Source: Progress of Theoretical and Experimental Physics (article, 2018-01-30)
Field: Chemistry — Physical and Theoretical Chemistry

On adiabatic pair potentials of highly charged colloid particles Generalizing the Debye-Hckel formalism, we develop a new mean field theory for adiabatic pair potentials of highly charged particles in colloid dispersions. The unoccupied volume and the osmotic pressure are the key concepts to describe the chemical and thermodynamical equilibrium of the gas of small ions in the outside region of all of the colloid particles. To define the proper thermodynamic quantities, it is postulated to take an ensemble averaging with respect to the particle configurations in the integrals for their densities consisting of the electric potential satisfying a set of equations that are derived by linearizing the Poisson-Boltzmann equation. With the Fourier integral representation of the electric potential, we calculate first the internal electric energy of the system from which the Helmholtz free energy is obtained through the Legendre transformation. Then, the Gibbs free energy is calculated using both ways of the Legendre transformation with respect to the unoccupied volume and the summation of chemical potentials. The thermodynamic functions provide three types of pair potentials, all of which are inversely proportional to the fraction of the unoccupied volume. At the limit when the fraction factor reduces to unity, the Helmholtz pair potential turns exactly into the well known Derjaguin-Landau-Verwey-Overbeek repulsive potential. The Gibbs pair potential possessing a medium-range strong repulsive part and a long-range weak attractive tail can explain the Schulze-Hardy rule for coagulation in combination with the van der Waals-London potential and describes a rich variety of phenomena of phase transitions observed in the dilute dispersions of highly charged particles. ........ Physics ; Pair potential ; Helmholtz free energy ; Legendre transformation ; Adiabatic process ; Thermodynamic potential ; Grand potential ; Internal energy ; Gibbs free energy ; Thermodynamics ; Quantum mechanics ; Classical mechanics Electrostatics and Colloid Interactions ; Material Dynamics and Properties ; Spectroscopy and Quantum Chemical Studies
Authors: M.A. Harvey | S. Suárez | Pavel N. Zolotarev | Davide Μ. Proserpio | Ricardo Baggio
Source: Acta Crystallographica Section C Structural Chemistry (article, 2018-02-23)
Field: Chemistry — Inorganic Chemistry

Topological study of diverse hydrogen-bonded patterns found in a system of a nickel(II) complex and the sulfate anion A nickel(II) coordination complex, bis[2,6-bis(1H-benzimidazol-2-yl-κN<sup>3</sup>)pyridine-κN]nickel(II) sulfate, [Ni(C<sub>19</sub>H<sub>13</sub>N<sub>5</sub>)<sub>2</sub>]SO<sub>4</sub> or [Ni(H<sub>2</sub>L)<sub>2</sub>]SO<sub>4</sub>, having four peripheral tetrahedrally oriented N-H donor units, combines with sulfate bridges to create hydrogen-bonded structures of varied dimensionality. The three crystal structures reported herein in the space groups P2<sub>1</sub>2<sub>1</sub>2<sub>1</sub>, I-4 and Pccn are defined solely by strong charge-assisted N-H...O hydrogen bonds and contain disordered guests (water and dimethylformamide) that vary in size, shape and degree of hydrophilicity. Two of the compounds are channelled solids with three-dimensional structures, while the third is one-dimensional in nature. In spite of their differences, all three present a striking resemblance to the previously reported anhydrous relative [Guo et al. (2011). Chin. J. Inorg. Chem. 27, 1517-1520], which is considered as the reference framework from which all three title compounds are derived. The hydrogen-bonded frameworks are described and compared using crystallographic and topological approaches. Nickel ; Crystallography ; Anhydrous ; Sulfate ; Chemistry ; Hydrogen bond ; Pyridine ; Dimethylformamide ; Crystal structure ; Topology (electrical circuits) ; Solvent ; Molecule ; Combinatorics ; Mathematics ; Medicinal chemistry ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Crystal structures of chemical compounds ; Crystallography and molecular interactions
Authors: Mohammed Jabbar Hussein | Suaad Sahib Hindal | Amany Akram Awaad
Source: International Journal of Structural Glass and Advanced Materials Research (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Preparation of Porous Silicon P-Type and Thermal Diffusivity Measurement Using Photoacoustic Technique Porous silicon (PSi) layers were formed on a p-type Si wafer. Electrochemical method was used to prepare 36 samples with three values of current density (10, 20 and 30) mA/cm 2 , each involved ( 20, 40, 60 and 80) min etching times the samples were heated to three selected temperatures of 100, 200 and 350C in three groups. The first group covers 12 samples corresponding to 10 mA/cm 2 while the other two correspond to the remaining values of current density respectively. Each annealing process for these sample groups lasted three hours in ambient air. The morphology of the layers, before and after annealing, formed by this method was investigated by Scanning Electron Microscope (SEM). Photoacoustic technique (PA) was employed carry out Thermal Diffusivity (TD) measurements. In this study, the porosity and thickness porous increased with increasing current density and etching time. While the thermal diffusivity TD increases with increasing annealing temperature. Thermal diffusivity ; Porous silicon ; Materials science ; Annealing (glass) ; Porosity ; Wafer ; Scanning electron microscope ; Analytical Chemistry (journal) ; Silicon ; Current density ; Composite material ; Etching (microfabrication) ; Optoelectronics ; Chemistry ; Chromatography Silicon Nanostructures and Photoluminescence ; Nanowire Synthesis and Applications ; Semiconductor materials and interfaces
Authors: Sabine Amon | Fabienne Meier‐Abt | Ludovic Gillet | Slavica Dimitrieva | Alexandre Theocharides | Markus G. Manz | Ruedi Aebersold
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-07-17)
Field: Chemistry — Spectroscopy

Ultra-sensitive proteome profiling of FACS-isolated cell populations by data-independent acquisition-MS: Application to human hematopoietic stem and progenitor cells ABSTRACT Physiological processes in multicellular organisms depend on the function and interactions of a multitude of specialized cell types operating in context. Fluorescence-activated cell sorting (FACS) provides a powerful tool to determine the cell type composition of complex mixtures and to purify highly homogeneous cell populations using a small number of differentially expressed marker proteins. These populations can be further characterized, e.g. by phenotypic or molecular analyses. We describe an ultra-sensitive mass spectrometric method for the robust quantitative and reproducible proteomic analysis of cohorts of FACS-isolated cell samples. It uses a minimum of post-sorting sample processing steps prior to data-independent acquisition MS on a current generation Orbitrap hybrid mass spectrometer. The method provides highly accurate and reproducible quantitative proteome profiles across the cohort with an average coefficient of variance &lt;15% from as little as 150 ng of total peptide mass. We quantified the proteome of 25,000 sorted human hematopoietic stem/multipotent progenitor cell and three committed progenitor cell subpopulations (common myeloid progenitors, megakaryocyte-erythrocyte progenitors and granulocyte-macrophage progenitors) isolated from five healthy donors. On average, 5,851 protein groups were identified per sample. After stringent filtering, a subset of 4,131 protein groups (≥2 peptides) was used for differential comparison across the 20 samples, defining unique proteomic signatures for each cell type tested. A comparison of proteomic and transcriptomic profiles of the four cell types indicated hematopoietic stem/multipotent progenitor cell-specific divergent regulation of biochemical processes that are essential for maintaining stemness and were detected at the proteome rather than the transcriptome level. The technology supports the generation of extensive and accurate quantitative proteomic profiles from low numbers of FACS-purified cells providing new information about the biochemical state of the analyzed cell types that is essential for basic and translational research. Biology ; Progenitor cell ; Proteome ; Cell sorting ; Stem cell ; Haematopoiesis ; Cell biology ; Proteomics ; Cell type ; Computational biology ; Cell ; Molecular biology ; Flow cytometry ; Genetics ; Gene Advanced Proteomics Techniques and Applications ; Glycosylation and Glycoproteins Research ; Chemokine receptors and signaling
Authors: Muaaz Gul Awan | Fahad Saeed
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-04-18)
Field: Chemistry — Spectroscopy

MaSS-Simulator: A highly configurable MS/MS simulator for generating test datasets for big data algorithms Abstract Mass Spectrometry (MS) based proteomics has become an essential tool in the study of proteins. The big data from MS machines has led to the development of novel serial and parallel algorithmic tools. However, the absence of data benchmarks and ground truth makes the algorithmic integrity testing and reproducibility a challenging problem. To this end, we present MaSS-Simulator, which is an easy to use simulator and can be configured to generate MS/MS datasets for a wide variety of conditions with known ground truths. MaSS-Simulator offers a large number of configuration options to simulate control datasets with desired properties thus enabling rigorous and large scale algorithmic testing. We assessed 8,031 spectra generated by MaSS-Simulator by comparing them against the experimentally generated spectra of same peptides. Our results showed that MaSS-Simulator generated spectra were very close to the real-experimental spectra and had a relative-error distribution centered around 25%. In contrast the theoretical spectra for same peptides had relative-error distribution centered around 150%. Source code, executables and a user manual can be downloaded from https://github.com/pcdslab/MaSS-Simulator Executable ; Computer science ; Simulation ; Replicate ; Algorithm ; Operating system ; Mathematics Advanced Proteomics Techniques and Applications ; Mass Spectrometry Techniques and Applications ; Metabolomics and Mass Spectrometry Studies
Authors: C. Mattone | M. Antonello | M. Locatelli | V. Arosio | Luca Malinverno | S. Lomazzi | R. De Asmundis
Source:  (article, 2018-07-25)
Field: Materials Science — Materials Chemistry

CAEN Educational: Nuclear and Particle Physics Experiments A., an important industrial spin-off of the INFN (National Institute for Nuclear Physics), is pleased to present its new activities in the educational field. CAEN brings the experience acquired in almost 40 years of collaboration with the High Energy & Nuclear Physics community into the university educational laboratories by providing modern physics experiments based on the latest technologies and instrumentation. CAEN has realized different modular Educational Kits, all based on Silicon Photomultipliers (SiPM) state of-the-art light sensors with single photon sensitivity and unprecedented photon number resolving capability. Nuclear physics ; Physics ; Particle (ecology) ; Computer science ; Geology Graphite, nuclear technology, radiation studies ; Nuclear and radioactivity studies
Authors: Jeff Gelb | Benjamin Stripe | Xiaolin Yang | Sylvia Lewis | S. H. Lau | Wenbing Yun
Source: Microscopy and Microanalysis (article, 2018-08-01)
Field: Materials Science — Surfaces, Coatings and Films

Mapping Subsurface Composition with Attogram Sensitivity using Micro-XRF An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the 'Save PDF' action button. Sensitivity (control systems) ; Composition (language) ; Remote sensing ; Content (measure theory) ; Environmental science ; Computer science ; Geology ; Mathematics ; Engineering ; Art Electron and X-Ray Spectroscopy Techniques ; X-ray Spectroscopy and Fluorescence Analysis ; Ion-surface interactions and analysis
Authors: Wayne Zhao | M. Gribelyuk
Source: Microscopy and Microanalysis (article, 2018-08-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Validation of Minimum Electron Beam Dosage on Characterization of Carbon-Depletion in ULK Dielectric Materials by EELS Quantifications An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Characterization (materials science) ; Dielectric ; Materials science ; Cathode ray ; Carbon fibers ; Electron ; Optoelectronics ; Nanotechnology ; Composite material ; Physics Copper Interconnects and Reliability ; Semiconductor materials and devices ; Muon and positron interactions and applications
Authors: Jouko Virtanen | Yang Zhang
Source: Acta Crystallographica Section D Structural Biology (article, 2018-06-08)
Field: Materials Science — Materials Chemistry

<i>MR-REX</i>: molecular replacement by cooperative conformational search and occupancy optimization on low-accuracy protein models Molecular replacement (MR) has commonly been employed to derive the phase information in protein crystal X-ray diffraction, but its success rate decreases rapidly when the search model is dissimilar to the target. MR-REX has been developed to perform an MR search by replica-exchange Monte Carlo simulations, which enables cooperative rotation and translation searches and simultaneous clash and occupancy optimization. MR-REX was tested on a set of 1303 protein structures of different accuracies and successfully placed 699 structures at positions that have an r.m.s.d. of below 2 Å to the target position, which is 10% higher than was obtained by Phaser. However, cases studies show that many of the models for which Phaser failed and MR-REX succeeded can be solved by Phaser by pruning them and using nondefault parameters. The factors effecting success and the parts of the methodology which lead to success are studied. The results demonstrate a new avenue for molecular replacement which outperforms (and has results that are complementary to) the state-of-the-art MR methods, in particular for distantly homologous proteins. Phaser ; Molecular replacement ; Translation (biology) ; Monte Carlo method ; Algorithm ; Computer science ; Physics ; Biological system ; Protein structure ; Biology ; Mathematics ; Nuclear magnetic resonance ; Optics ; Statistics ; Genetics Enzyme Structure and Function ; Protein Structure and Dynamics ; RNA and protein synthesis mechanisms
Authors: Artem Chesalkin | Petr Moldřík | Alexandr Martaus
Source: Preprints.org (preprint, 2018-05-15)
Field: Materials Science — Materials Chemistry

La-Ni based Alloys Preparation for Hydrogen Reversible Sorption and their Application for Renewable Energy Storage Metal hydrides are one of the types of functional materials that allow safe and compact storage of a large amount of hydrogen, which is increasingly used today as an alternate fuel or energy source. The possibility of obtaining the initial energy necessary for the production of hydrogen by electrolysis process from renewable energy sources, such as solar panels and wind generators, makes hydrogen energetic quite attractive and rapidly developing industry sector. Solid form of hydrogen storage with the possibility of reversible sorption, gives opportunity for creation autonomous energy storage systems. La-Ni based alloys allow hydrogen storing at ambient temperatures and pressure not higher than 15 bar, which makes the application of these alloys quite practical, interesting and prospects for analysis and modifications on the ways of stored hydrogen capacity increasing, alloys price reducing and application for renewable energy storage. Hydrogen storage ; Renewable energy ; Hydrogen ; Energy storage ; Hydrogen economy ; Hydrogen fuel ; Process engineering ; Energy carrier ; Hydrogen production ; Sorption ; Hydrogen technologies ; Electrolysis ; Materials science ; High-pressure electrolysis ; Environmental science ; Waste management ; Chemistry ; Thermodynamics ; Engineering ; Electrical engineering ; Physics Hydrogen Storage and Materials ; Material Properties and Applications ; Surface Treatment and Coatings
Authors: Juho Heininen
Source: Jyväskylä University Digital Archive (University of Jyväskylä) (article, 2018-01-01)
Field: Chemistry — Analytical Chemistry

Mass spectrometric analysis of heavy and base oils Base oil production from crude oil has become more complex as demanded product properties, yield objective and field competition have increased interest in research towards high viscosity index (VI) base oils. Conventional lubricant grade base oil enjoyed biggest market share until 2000-2004 but now high VHVI product demands have introduced also novel production methods for heavy-type base oils such as Ficsher-Tropsch method based gas-to-liquid (GTL) and poly-internal-olefin (PIO) base oils. In this MSc, different mass spectrometric methods for heavy and base oils where compared and in-house field ionization method was characterized and method validation was begun. Base oil mass analytics uses mainly Fourier transformation ion cyclotron resonance (FT-ICR) and sector mass analyzers with soft ionization methods as well as novel ambient ionization (AI) methods. While heaviest asphaltenes compounds require resolutions that are achievable only by FT-ICR instruments majority of petroleum studies including quantitative fraction studies can be done with more cost-efficient and operator-friendly sector and Orbitrap instruments. Novel AI methods are arguably fastest expanding area of mass spectrometry and provide interesting field to follow also for petroleum analysis. Chemistry ; Base (topology) ; Environmental science ; Environmental chemistry ; Chromatography ; Mathematics Petroleum Processing and Analysis ; Mass Spectrometry Techniques and Applications ; Hydrocarbon exploration and reservoir analysis
Authors: Michael M. Azad
Source: NC Digital Online Collection of Knowledge and Scholarship (The University of North Carolina at Greensboro) (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

A comparison study of superabsorbent polymer with microwave - assisted polymerization and free radical solution polymerization: synthesis, kinetics, and applications This purpose of this research is to compare the formation kinetics of two approaches to synthesizing crosslinked polyacrylic acid (x-PAA) superabsorbent polymers (SAP). Specifically, it tests the applicability of the reported general rate expression for free radical solution polymerization to the synthesis of x-PAA SAPs via Microwave-Assisted Polymerization (MAP) and Free Radical Solution Polymerization (FRSP). This study of FRSP and MAP formation kinetics of x-PAA superabsorbent materials provides predictive models and new foundational insights into the rate-limiting steps for these three-dimensional polymerization reactions. These foundational models, based on the observed results from the designed kinetic studies, may help to guide and enable the design of new networked polymers with enhanced functional properties. The published complex mechanism of PAA polymerization, which was assumed to explain the kinetics of superabsorbent polymerization, does not seem to be valid in FRSP and MAP synthesis of PAA SAPs. In fact, for these kinetic studies, the data supported none of the initial hypotheses for all the data in a given reaction. For the FRSP, only a sequential kinetic model, i.e., zero-order followed by the first order in monomer model explains the observed data. For the MAP PAA SAP syntheses, several sequential kinetic models may explain the observed data. A first-order model supports the first-half-reaction, and a zero-order model explains the second-half-reaction. So overall, the key findings show that one cannot conclude with 99% confidence (2s) the existence of a single zero or first-order kinetic process over the entire reaction for each type polymerization, i.e., MAP or FRSP. However, there are regions of sequential zero-order and/or first-order kinetics that explain the dominant mechanistic modes for both types of polymerizations. The MAP reaction, due to its rapid nature, enables a much more uniform distribution of inert material, such as clay, that can be achieved with the FRSP process. Percolation theory provides a way to understand why these interconnected channels help to enhance the movement of a liquid through the PAA SAP’s gel network. This theory could explain why a clay containing polymer made with the MAP process exhibits higher and more consistent permeability than a corresponding system synthesized via the FRSP reaction. Polymerization ; Radical polymerization ; Kinetics ; Polymer chemistry ; Chemistry ; Monomer ; Solution polymerization ; Polyacrylic acid ; Polymer ; Organic chemistry ; Physics Advanced Polymer Synthesis and Characterization
Authors: Nour Halawani | Jean-Louis Augé | Olivier Gain | V. Griseri | G. Teyssèdre | Sébastien Pruvost
Source: Polymer Degradation and Stability (article, 2018-06-01)
Field: Materials Science — Materials Chemistry

Poly-etherimide epoxy diamine blends: Conductivity and breakdown voltage measurements at room temperature Epoxy ; Materials science ; Thermosetting polymer ; Composite material ; Thermoplastic ; Space charge ; Conductivity ; Thermal conduction ; Diamine ; Polymer chemistry ; Chemistry High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Electrostatic Discharge in Electronics