jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Supriya Atta | Laura Fabris
Source: ChemRxiv (preprint, 2018-08-10)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Understanding the Role of AgNO3 Concentration and Seed Morphology to Achieve Tunable Shape Control in Gold Nanostars &lt;div&gt;Gold nanostars are one of the most fascinating anisotropic nanoparticles. Nanostar morphology can be controlled by changing various synthetic parameters; however, the detailed&lt;/div&gt;&lt;div&gt;growth mechanisms are not fully understood. Herein, we investigate this process in six-branched nanostars, focusing first on the properties of the single crystalline seed, which evolves to include penta-twinned defects as the gateway to anisotropic growth into 6-branched nanostars. In particular, we report on a high-yield seed-mediated protocol for the synthesis of these particles with high monodispersity in the presence of Triton-X, ascorbic acid, and AgNO3. Detailed&lt;/div&gt;&lt;div&gt;spectroscopic and microscopic analyses have allowed the identification of several key intermediates in the growth process, revealing that it proceeds via penta-twinned intermediate seeds. Importantly, we report the first experimental evidence tracking the location of silver with&lt;/div&gt;&lt;div&gt;sub-nanometer resolution and prove its role as stabilizing agent in these highly branched nanostructures. Our results indicate that metallic silver on the spikes stabilizes the nanostar morphology, and that the remaining silver, present when AgNO3 is added at high concentration, deposits on the core and between the base of neighboring spikes. Importantly, we also demonstrate the possibility to achieve monodispersity, reproducibility, and tunability in colloidal gold nanostars that are substantially higher than previously reported, which could be leveraged to carry out holistic computational-experimental studies to understand, predict, and tailor their plasmonic response.&lt;/div&gt;&lt;div&gt;&lt;br&gt;&lt;/div&gt; Nanotechnology ; Materials science ; Ascorbic acid ; Morphology (biology) ; Nanostructure ; Chemical engineering ; Chemistry ; Biology Gold and Silver Nanoparticles Synthesis and Applications
Authors: Thomas Hillenbrand | Dieter Brüggemann
Source: LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (article, 2018-09-28)
Field: Chemistry — Analytical Chemistry

Charakterisierung der Verdunstung von frei fallenden Tropfen aus variierten Ethanol-Alkan-Gemischen mittels Raman-Spektroskopie Chemistry Petroleum Processing and Analysis ; Catalysis and Hydrodesulfurization Studies ; Spectroscopy and Quantum Chemical Studies
Authors: George Alexandru Nemneş | T. L. Mitran | Andrei Manolescu | Daniela Dragoman
Source: arXiv (Cornell University) (preprint, 2018-09-03)
Field: Materials Science — Materials Chemistry

Electric field effect in boron and nitrogen doped graphene bilayers Unlike single layer graphene, in the case of $AB$-stacked bilayer graphene (BLG) one can induce a non-zero energy gap by breaking the inversion symmetry between the two layers using a perpendicular electric field. This is an essential requirement in field-effect applications, particularly since the induced gap in BLG systems can be further tuned by the magnitude of the external electric field. Doping is another way to modify the electronic properties of graphene based systems. We investigate here BLG systems doped with boron and nitrogen in the presence of external electric field, in the framework of density functional theory (DFT) calculations. Highly doped BLG systems are known to behave as degenerate semiconductors, where the Fermi energy depends on the doping concentration but, in addition, we show that the electronic properties drastically depend also on the applied electric field. By changing the magnitude and the orientation of the electric field, the gap size and position relative to the Fermi level may be tuned, essentially controlling the effect of the extrinsic doping. In this context, we discuss in how far the external electric field may suitably adjust the effective doping and, implicitly, the conduction properties of doped BLG systems. Condensed matter physics ; Electric field ; Bilayer graphene ; Doping ; Materials science ; Graphene ; Band gap ; Fermi level ; Semiconductor ; Fermi energy ; Physics ; Nanotechnology ; Optoelectronics ; Electron ; Quantum mechanics Graphene research and applications ; Quantum and electron transport phenomena ; Molecular Junctions and Nanostructures
Authors: Elizabeth Alene Wood
Source: Research Exchange (Washington State University) (article, 2018-01-01)
Field: Chemistry — Analytical Chemistry

Efficacy Testing of Food Industry Cleaning Agents on the Removal of Engineered Nanoparticles from the Skins of Grape Tomatoes (Solanum lycopersicum) Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FTIR) and Support Vector Machine (SVM) Learning Edwards next-for your endless sage wisdom, mentorship, and guidance.You always knew just what to say to get me through my troubles and make me feel better.I greatly enjoyed our conversations as well as the time we spent putting on Food Chem each year.I would like to thank my Pullman friends next-Sasha and Kari-for keeping me sane (even when I wasn't!) and reminding me to have fun every once in a while :).Without you guys, I probably would have lost my mind and/or never left my apartment, so I thank you.I want to especially thank you for all the times you sat with me and let me rant and cry through my toughest times.I will miss you both and I hope we can stay in touch.Next, to the older, wiser, powerful STEM women back home, Miss Debbie and Carole-thank you for your never--ending support and motivation throughout this time.Knowing you ladies did it and made it through school and know EXACTLY how I feel (Ahhhhhhhhh!)helped motivate me to keep going.Finally, I would like to thank my parents for supporting, encouraging, and believing in me even when I didn't believe in myself.The both of you were there through all of my ups and downs, Attenuated total reflection ; Fourier transform infrared spectroscopy ; Fourier transform ; Spectroscopy ; Solanum ; Reflection (computer programming) ; Chemistry ; Nanoparticle ; Infrared ; Materials science ; Food science ; Horticulture ; Optics ; Nanotechnology ; Mathematics ; Biology ; Computer science ; Physics Spectroscopy and Chemometric Analyses
Authors: William R Ehrhardt
Source: BearWorks (Missouri State University) (article, 2018-01-01)
Field: Chemistry — Spectroscopy

NMR Spectroscopic Properties of Nucleotides, and a New Method of Numeric Calculation of Raman Intensities for Organic Molecules General and accurate computational methodologies are currently lacking for large chemical systems. This is primarily due to the computational expense required to perform calculations on systems with one hundred or more atoms. Calculated spectroscopic properties could aid in the process of elucidating structural features of large biologically relevant molecules if accurate and inexpensive methods are developed. Towards this end the first steps were taken to design a general methodology for predicting NMR chemical shifts of large nucleic acid systems. It was found that HF and semi-empirical methods were not sufficient for optimization of nucleobases, and therefore larger nucleotide or nucleic acid systems. It was also found that there is little difference in performance between DFT methods for prediction of NMR shifts of nucleobases as long as hydrogen bonding requirements are satisfied. To potentially reduce the computational expense of calculating Raman activities, a new and potentially inexpensive numerical method was developed. This method utilizes volume changes as a basis for approximating polarizability changes over the course of molecular vibrations. Raman intensities calculated using this methodology were compared to experimentally obtained Raman intensities by linear regression. While a positive correlation was found further refinement is needed. Raman spectroscopy ; Molecule ; Nucleotide ; Organic molecules ; Chemistry ; Computational chemistry ; Analytical Chemistry (journal) ; Nuclear magnetic resonance ; Physics ; Materials science ; Optics ; Organic chemistry ; Biochemistry Molecular spectroscopy and chirality
Authors: James Magato
Source: OhioLink ETD Center (Ohio Library and Information Network) (article, 2018-01-01)
Field: Materials Science — Polymers and Plastics

Process Model and Sensor Based Optimization of Polyimide Prepreg Compaction During Composite Cure PMR-type polyimide prepregs are challenging to fabricate into high quality composites due to volatiles that are generated and must be removed in-situ during processing.Despite several decades of academic and industrial study, the core challenge of effective and repeatable volatile removal has still plagued manufacturers of polyimide composite structures.A method for the in-situ characterization and modeling of polyimide compaction during composite fabrication would greatly help in understanding and controlling the process.To this end, the current work was conducted to develop a polyimide prepreg compaction model, as well as practical characterization techniques for the resin rheology, volatile generation, and subsequent volatile removal from the prepreg stack during composite fabrication.Two PMR-type polyimide / carbon fiber prepreg systems were studied: one containing a simplified / model resin system, and one containing the commercially available RM-1100 resin system.Thermal analysis was used to characterize volatile generation, reaction rates, and rheology for each prepreg v system.A novel approach was used to measure the thickness of a prepreg stack in-situ during vacuum bag / oven processing using a high-temperature LVDT.Neural networks were then used to model the volatile generation, rheology, and composite compaction.These tools were then combined in a global model that showed the key interrelationships in these coupled phenomena and how that information can be used to select the optimum temperature of pressure application to minimize void content.Two autoclave trials were conducted for RM-1100 which demonstrated the ability to reduce void content from 9.5% to 3.1% by using the information and criteria developed by this methodology.Overall the results showed that the methods developed in this study were able to accurately measure polyimide prepreg thickness in-situ during the imidization phase of the cure and were effective in cure cycle optimization.This model based approach is intended to greatly reduce experimental trial-and-error in cure cycle development for PMR type polyimide composites. Composite number ; Polyimide ; Compaction ; Process (computing) ; Materials science ; Composite material ; Process engineering ; Computer science ; Layer (electronics) ; Engineering Synthesis and properties of polymers ; Epoxy Resin Curing Processes ; Injection Molding Process and Properties
Authors: Matthew S. MacLennan
Source: cIRcle (University of British Columbia) (article, 2018-01-01)
Field: Chemistry — Spectroscopy

Capillary electrophoresis-mass spectrometry and complementary approaches for semi-quantitative analysis of samples with complex matrices Capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) combines the superior separation efficiency of CE with the detection capability of MS to provide information-rich data on samples with complex matrices. CE-ESI-MS is applied to a range of complex mixtures to semi-quantify unknown components and find patterns among groups of samples. The first part of this thesis tells how the industrial generation of oil sands process-affected waters (OSPW) poses an environmental threat, and a review is given on the state-of-the-art of analytical chemistry in the semi-quantification of toxic naphthenic acid fraction compounds (NAFC) in OSPW. The chapter ends with a technical description of the CE-ESI-MS system which was utilized. CE-ESI-MS was demonstrated to produce effective analyses of a well-known complex mixture: human urine. CE-ESI-MS was used to quantify and “fingerprint” components in human urine via targeted and untargeted analyses of the sub-5 kDa urine metabolome of patients with prostate and/or bladder cancer. For targeted analysis, endogenous levels of sarcosine and 5 other metabolites were quantified in four patients and in a pooled healthy urine sample. An untargeted analysis of patient urine was also performed identifying over 400 distinct molecular features per patient. Next, a CE-ESI-MS method was developed for the analysis of a relatively unknown complex mixture: NAFCs in OSPW. A standard mixture of amine-derivatized naphthenic acids was analyzed in under 15 min, detecting NAFCs between m/z 250 and 800. Derivatization of NAFCs consisted of two-step amidation reactions mediated by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide in three different solvents. The optimum BGE composition was determined to be 30% (V/V) methanol in water and 2% (V/V) formic acid. The optimized CE-ESI-MS method was then used to find patterns in NAFCs across porewater samples impacted by oil sands waste. CE-ESI-MS, Orbitrap MS, and a standard GC-FID method were used to characterize porewater samples. Differences in measured amounts of total petroleum hydrocarbon by GC-FID and NAFC by HRMS indicate that the two methods provide complementary information about dissolved organic species in water leachate samples. CE-ESI-MS also provides complementary information and is a feasible and practical option for source evaluation of NAFCs in water. Mass spectrometry ; Capillary electrophoresis ; Chromatography ; Chemistry ; Quantitative analysis (chemistry) Mass Spectrometry Techniques and Applications ; Microfluidic and Capillary Electrophoresis Applications ; Ion-surface interactions and analysis
Authors: Sergei Posysaev | О. С. Мирошниченко | M. Alatalo | Duy Le | Talat S. Rahman
Source: ChemRxiv (preprint, 2018-10-22)
Field: Materials Science — Materials Chemistry

Oxidation States of Binary Oxides from Data Analytics of the Electronic Structure A connection between the oxidation state (OS) and Bader charge has been missing so far. To our knowledge, all previous work tried to connect OS with Bader charges only with few compounds. The aim of this work was to find a dependency between OS and Bader charge, using a large number of compounds from an open database. We show that a correlation indeed exists between OSs and Bader charges using the simplest machine learning algorithm, linear regression. The applicability of determining OS by Bader charges in mixed-valence compounds and surfaces is considered. Valence (chemistry) ; Charge (physics) ; Binary number ; Computer science ; Physics ; Mathematics ; Quantum mechanics Machine Learning in Materials Science
Authors: J.J. Shea
Source: IEEE Electrical Insulation Magazine (article, 2018-10-25)
Field: Chemistry — Physical and Theoretical Chemistry

Book Reviews [7 Books reviewed] The following books are reviewed in this issue of the publication: High Power Microwave Tubes—Basics and Trends, V. Kesari and B. N. Basu; A-Level Chemistry's Best Kept Secrets!—What Top Students Know That You Don't, D. Tan and L. Pereira; An Introduction to Chemical Kinetics, C. Vallance; Control of Power Electronic Converters and Systems, Volume 1, F. Blaabjerg; Wireless Sensor Systems for Extreme Environments, H. F. Rashvand and A. Abedi; Transformer Aging-Monitoring and Estimation Techniques, T. K. Saha and P. Purkait; Quantum Field Theory, H. Fritzsch. Converters ; Microwave ; Engineering physics ; Electrical engineering ; Transformer ; Wireless ; Computer science ; Engineering ; Library science ; Materials science ; Physics ; Telecommunications ; Voltage Various Chemistry Research Topics ; Inorganic and Organometallic Chemistry
Authors: Lusia Lusia Narsia Amsad | S Liliasari | Asep Kadarohman | Ratnaningsih Eko Sardjono
Source:  (article, 2018-01-01)
Field: Chemistry — Physical and Theoretical Chemistry

How are studentsr ability and perception in using media through synthesis organic chemistry learning? Lecturer usually uses media in order to help students' understanding about organic chemistry. In this research, the aim is to find out the ability and perception of students in learning by using media in the form of online and offline. The offline media we used was namely Spartan Student V6, and ChemAxon Reactor software, while the online media used is Reaction Predictor. Participants from this study were 16 students from one of the state universities in Papua. This research is a descriptive research by using the percentage of data and from questionnaire results. It shows the ability of students' in using media.. Based on the results of this study, it was found that the ability of students in using mediathrough the learning of organic synthesis was still low, around 10-40%. The media that highest used is Reaction Predictor onlinemedia and the lowest used is Spartan Student V6 offline media. It was also known that the results of students' responses for using media in learning synthetic organic chemistry are positive. Perception ; Computer science ; Chemistry ; Multimedia ; Psychology ; Neuroscience Various Chemistry Research Topics ; Science Education and Pedagogy ; Mobile Learning in Education
Authors: Eemeli Leppäaho
Source: Aaltodoc (Aalto University) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Bayesian Multi-View Factor Models for Drug Response and Brain Imaging Studies This thesis investigates knowledge inference from measurements of multiple data sources, motivated by technologies in a wide range of domains allowing effective measurement of several related, but heterogeneous data sources. In life sciences, examples of this kind of "multi-view" data are brain imaging data of multiple subjects along with description of the experimental stimuli, as well as drug response studies including measurements regarding the expression level, copy number variation and mutation of genes in cell lines. Data analyses have been typically related to analyzing the structure of a single data source, or the effect of one data source to another. The multi-view data inspected in this thesis results in a more complex problem: besides the structure of each of the data sources, the relations between the data sources are of high interest as well. &#13;\n&#13;\nThis thesis addresses modern multi-view data analysis problems using Bayesian latent variable models. They are a natural choice for developing models in order to gain knowledge about multiple data sources and their relations; they allow for missing values in the data, incorporating prior information to the modelling problem and estimating the uncertainty present in the inference. The key contributions of this thesis include formulating a low-rank data source relation model and presenting biclustering using sparse priors, as well as a relaxed formulation of tensor factorization. All the developed models have been published as open-source software, enabling wide-spread use and further development. &#13;\n&#13;\nThe presented machine learning tools are demonstrated using drug response and brain imaging studies, for both of which predictive performance above state-of-the-art level is achieved. In the drug response studies, the models were able to accurately relate similar drugs, as well as detect known cancer genes affecting the responsiveness of cells to certain drugs. In the brain response studies the benefits of the presented methods were shown via increased accuracy in predicting brain responses, whereas the relaxed tensor decomposition allowed for a novel way of utilizing measurements for multiple subjects. Finally, the advantage of using a low-dimensional latent space is illustrated in a genome-wide association study in an especially challenging domain: when there exist measurements for only two hundred subjects, yet there exist some thousands of features regarding the subjects, with the study discovering a relevant gene associated with components of brain activity. Neuroimaging ; Bayesian probability ; Computer science ; Artificial intelligence ; Neuroscience ; Psychology Machine Learning in Materials Science ; Functional Brain Connectivity Studies ; Gene expression and cancer classification
Authors: Cody M. Sterling
Source: Skemman (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

A black-box explicit solvation protocol for calculation of redox potentials Redox potentials are important properties of molecules that represent the tendency of a molecule to either gain or lose electrons in a reaction, and are very sensitive to solvation effects. Properly accounting for the effects of a solvent around a molecule is an area of intense research, and implicit solvation models provide some success. Explicit solvation is ultimately necessary to accurately capture these effects, particularly when involving strong solute-solvent interactions, yet no standard method exists. This thesis proposes a general protocol to accurately calculate redox potentials of molecules in water, utilizing molecular dynamics (MD) simulations combined with vertical ionization energy (VIE) calculations of snapshots from those trajectories under the linear response approximation. For the dynamics simulation, we do quantum mechanics (QM)/molecular mechanics (MM) MD simulations of the solute inserted into a spherical water cluster, using the semi-empirical GFN-xTB method as QM method, with scaled OPLS-AA Lennard-Jones potentials for the QM-MM interaction, and TIP3P as MM water forcefield.&#13;\nFor the VIE calculations of snapshots from the MD trajectories, we investigate the importance of hydrogen bonding, solvent polarization and bulk effects, and propose a multi-step protocol to accurately account for these effects in a computationally-efficient manner. This uses a combination of wavefunction theory (HF and DLPNO-CCSD(T)), range-separated hybrid density functional theory (ωB97X), as well as non-polarizable (TIP3P) and polarizable (SWM4-DP) water forcefields.&#13;\nWe test the protocol on a small test set of 19 molecules with experimentally-available redox potentials, and the results show mean absolute errors of 0.17 eV, compared to 0.25 eV and 0.30 eV with SMD and CPCM implicit solvation models, respectively, for gas-solvent redox shifts. Additionally, the maximum error is 0.36 eV compared to 0.63 eV for SMD and 0.65 eV for CPCM. This protocol shows promise as a black-box tool for accurate calculation of redox potentials, particularly when involving strong interactions with water. Solvation ; Redox ; Protocol (science) ; Black box ; Computer science ; Chemistry ; Artificial intelligence ; Medicine ; Inorganic chemistry ; Biochemistry Free Radicals and Antioxidants ; Spectroscopy and Quantum Chemical Studies ; Electron Spin Resonance Studies