jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Salma Ahmed Al‐Zahrani | Maqsood Ahmad Malik | Shaeel A. Al‐Thabaiti | Zaheer Khan
Source: Applied Nanoscience (article, 2018-03-01)
Field: Chemistry — Organic Chemistry

Seedless synthesis and efficient recyclable catalytic activity of Ag@Fe nanocomposites towards methyl orange Abstract This work demonstrates a competitive reduction method of synthesis of nanomaterials. In this method along cetyltrimethylammonium bromide (CTAB), the reduction of Ag + and Fe 3+ ions is achieved by ascorbic acid-to-bimetallic Ag@Fe yellow-colored nanomaterials. The shape of UV–visible spectra and wavelengths absorbed of Ag@Fe can be tuned from ca. 290–600 nm by controlling [CTAB] and [Ag + ]. The apparent first-order rate constants were calculated within the approximation of 6.1 × 10 −3 s −1 . The as-prepared Ag@Fe NPs have been found to be very important catalyst in terms of depredate methyl orange in vicinity of sodium borohydride (NaBH 4 ), which exhibits excellent efficiency and re-usability in the prototypical reaction. The cmc of cationic surfactant CTAB has been determined by conductivity method under different experimental conditions. In the presence of CTAB, Ag + and Fe 3+ ions reduce to Ag@Fe core/shell nanoparticles, comprehend a change in wavelength and intensity of SRP band. The apparent first-order rate constant, activation energy, and turnover frequency for the methyl orange reduction catalyzed by Ag@Fe NPs were found to be 1.6 × 10 −3 s −1 , 58.2 kJ mol −1 , and 1.1 × 10 −3 s −1 , respectively. Catalysis ; Sodium borohydride ; Bimetallic strip ; Methyl orange ; Ascorbic acid ; Nanomaterials ; Nanochemistry ; Materials science ; Reaction rate constant ; Bromide ; Borohydride ; Nanocomposite ; Nanoparticle ; Nuclear chemistry ; Inorganic chemistry ; Chemistry ; Nanotechnology ; Kinetics ; Organic chemistry ; Photocatalysis Nanomaterials for catalytic reactions ; Nanocluster Synthesis and Applications ; Gold and Silver Nanoparticles Synthesis and Applications
Authors: Ziyi Zhang | Yufeng Jiang | Caili Huang | Yu Chai | Elise A. Goldfine | Feng Liu | Wenqian Feng | Joe Forth | Teresa E. Williams | Paul D. Ashby | Thomas P. Russell | Brett A. Helms
Source: Science Advances (article, 2018-08-01)
Field: Materials Science — Materials Chemistry

Guiding kinetic trajectories between jammed and unjammed states in 2D colloidal nanocrystal-polymer assemblies with zwitterionic ligands Mesostructured matter composed of colloidal nanocrystals in solidified architectures abounds with broadly tunable catalytic, magnetic, optoelectronic, and energy storing properties. Less common are liquid-like assemblies of colloidal nanocrystals in a condensed phase, which may have different energy transduction behaviors owing to their dynamic character. Limiting investigations into dynamic colloidal nanocrystal architectures is the lack of schemes to control or redirect the tendency of the system to solidify. We show how to solidify and subsequently reconfigure colloidal nanocrystal assemblies dimensionally confined to a liquid-liquid interface. Our success in this regard hinged on the development of competitive chemistries anchoring or releasing the nanocrystals to or from the interface. With these chemistries, it was possible to control the kinetic trajectory between quasi-two-dimensional jammed (solid-like) and unjammed (liquid-like) states. In future schemes, it may be possible to leverage this control to direct the formation or destruction of explicit physical pathways for energy carriers to migrate in the system in response to an external field. Nanocrystal ; Colloid ; Nanotechnology ; Materials science ; Kinetic control ; Limiting ; Kinetic energy ; Chemistry ; Catalysis ; Physics Pickering emulsions and particle stabilization ; Spectroscopy and Quantum Chemical Studies ; Material Dynamics and Properties
Authors: Bijal Vyas | Sadafara A. Pillai | Anita Bahadur | Pratap Bahadur
Source: Polymers (article, 2018-01-15)
Field: Materials Science — Biomaterials

A Comparative Study on Micellar and Solubilizing Behavior of Three EO-PO Based Star Block Copolymers Varying in Hydrophobicity and Their Application for the In Vitro Release of Anticancer Drugs The temperature and pH dependent self-assembly of three star shaped ethylene oxide-propylene oxide (EO-PO) block copolymers (Tetronics<sup>®</sup> 304, 904 and 908) with widely different hydrophobicity was examined in aqueous solutions. Physico-chemical methods viz. viscosity, cloud point, solubilization along with thermal, scattering and spectral techniques shows strongly temperature and salt dependent solution behavior. T304 possessing low molecular weight did not form micelles; moderately hydrophilic T904 remained as micelles at ambient temperature and showed micellar growth while very hydrophilic T908 formed micelles at elevated temperatures. The surface activity/micellization/solubilization power was favored in the presence of salt. The copolymers turn more hydrophilic in acidic pH due to protonation of central ethylene diamine moiety that hinders micelle formation. The solubilization of a model insoluble azo dye 1-(o-Tolylazo)-2-naphthol (Orange OT) and hydrophobic drugs (quercetin and curcumin) for copolymer solutions in aqueous and salt solutions are also reported. Among the three copolymers, T904 showed maximum solubility of dye and drugs, hence the in vitro release of drugs from T904 micelles was estimated and the effect on cytotoxicity of loading the drugs in T904 micelles was compared with the cytotoxicity of free drugs on the CHO-K1 cells. The results from the present work provide a better insight in selection of Tetronics<sup>®</sup> for their application in different therapeutic applications. Micelle ; Cloud point ; Copolymer ; Ethylene oxide ; Chemistry ; Lower critical solution temperature ; Aqueous solution ; Solubility ; Dynamic light scattering ; Micellar solutions ; Propylene oxide ; Critical micelle concentration ; Polymer chemistry ; Organic chemistry ; Materials science ; Nanoparticle ; Polymer ; Nanotechnology Nanoparticle-Based Drug Delivery ; Advanced Polymer Synthesis and Characterization ; Surfactants and Colloidal Systems
Authors: Ryan Djemili | Lucas Kocher | Stéphanie Durot | Anssi Peuronen | Kari Rissanen | Valérie Heitz
Source: Chemistry - A European Journal (article, 2018-12-10)
Field: Chemistry — Organic Chemistry

Positive Allosteric Control of Guests Encapsulation by Metal Binding to Covalent Porphyrin Cages The allosteric control of the receptor properties of two flexible covalent cages is reported. These receptors consist of two zinc(II) porphyrins connected by four linkers of two different sizes, each incorporating two 1,2,3-triazolyl ligands. Silver(I) ions act as effectors, responsible for an on/off encapsulation mechanism of neutral guest molecules. Binding silver(I) ions to the triazoles opens the cages and triggers the coordination of pyrazine or the encapsulation of N,N'-dibutyl-1,4,5,8-naphthalene diimide. The X-ray structure of the silver(I)-complexed receptor with short connectors is reported, revealing the hollow structure with a cavity well-defined by two eclipsed porphyrins. Rather unexpectedly, the crystallographic structure of this receptor with pyrazine as a guest molecule showed that the cavity is occupied by two pyrazines, each binding to the zinc(II) porphyrin in a monotopic fashion. Porphyrin ; Pyrazine ; Allosteric regulation ; Chemistry ; Molecule ; Covalent bond ; Metal ; Metal ions in aqueous solution ; Crystallography ; Zinc ; Stereochemistry ; Receptor ; Photochemistry ; Organic chemistry Supramolecular Chemistry and Complexes ; Molecular Sensors and Ion Detection ; Porphyrin and Phthalocyanine Chemistry
Authors: Cecilia de Agrela Pinto | Deni Mance | Tessa Sinnige | Mark A. Daniëls | Markus Weingarth | Marc Baldus
Source: Nature Communications (article, 2018-10-02)
Field: Chemistry — Spectroscopy

Formation of the β-barrel assembly machinery complex in lipid bilayers as seen by solid-state NMR The β-barrel assembly machinery (BAM) is a pentameric complex (BamA-E), which catalyzes the essential process of β-barrel protein insertion into the outer membrane of E. coli. Thus far, a detailed understanding of the insertion mechanism has been elusive but recent results suggest that local protein motion, in addition to the surrounding membrane environment, may be of critical relevance. We have devised a high-sensitivity solid-state NMR approach to directly probe protein motion and the structural changes associated with BAM complex assembly in lipid bilayers. Our results reveal how essential BamA domains, such as the interface formed by the polypeptide transport associated domains P4 and P5 become stabilized after complex formation and suggest that BamA β-barrel opening and P5 reorientation is directly related to complex formation in membranes. Both the lateral gate, as well as P5, exhibit local dynamics, a property that could play an integral role in substrate recognition and insertion. Barrel (horology) ; Solid-state nuclear magnetic resonance ; Lipid bilayer ; Solid-state ; Crystallography ; Chemistry ; Materials science ; Biophysics ; Nanotechnology ; Nuclear magnetic resonance ; Membrane ; Physics ; Biology ; Biochemistry ; Physical chemistry Advanced NMR Techniques and Applications ; Protein Structure and Dynamics ; Lipid Membrane Structure and Behavior
Authors: Hidayat Ullah Khan | Muhammad Amin | Ayaz Ahmad
Source: REVIEWS ON ADVANCED MATERIALS SCIENCE (article, 2018-05-01)
Field: Materials Science — Materials Chemistry

Characteristics of Silicone Composites for High Voltage Insulations Abstract Silicone rubber (SiR) composites have been widely used for high voltage (HV) electrical and non-electrical applications for the last three decades. To increase the long-term performance of SiR composites under diverse environmental, mechanical and electrical stresses; detailed characterization and aging analysis is required. This review article presents a comprehensive survey on SiR composites that are used in HV applications. Particular emphasis is on silicon (Si) applications, chemistry, polymerization, silicone rubber properties enhancement by addition of fillers, composite materials, engineering requirements of polymer insulants, overview of high voltage (HV) electrical insulators and their aging. In addition, this review article includes appropriate discussions concerning the influence of fillers (micro/nano-sized) on the physical, thermal, mechanical and electrical properties of base polymer. Tensile strength, elongation at break, hardness, thermal degradation, dielectric strength, surface resistivity, volume resistivity, tracking/erosion resistance, partial discharge and water immersion resistance of SiR composites are analyzed. Finally, it was inferred that in order to diversify the SiR blends with micro/nano fillers and optimize their properties for particular applications further research work must be conducted. Materials science ; Composite material ; Silicone rubber ; Ultimate tensile strength ; Dielectric ; Dielectric strength ; High voltage ; Polymer ; Voltage ; Electrical engineering High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Electrical Fault Detection and Protection
Authors: Wei Zhang | Sansan Ao | J.P. Oliveira | Zhi Zeng | Yifei Huang | Zhen Luo
Source: Materials (article, 2018-09-26)
Field: Materials Science — Materials Chemistry

Microstructural Characterization and Mechanical Behavior of NiTi Shape Memory Alloys Ultrasonic Joints Using Cu Interlayer NiTi shape memory alloys (SMAs) are a class of functional materials which can be significantly deformed and recover their original shape via a reversible martensitic phase transformation. Developing effective joining techniques can expand the application of SMAs in the medical and engineering fields. In this study, ultrasonic spot welding (USW), a solid-state joining technique, was used to join NiTi sheets using a Cu interlayer in between the two joining sheets. The influence of USW process on the microstructural characteristics and mechanical behavior of the NiTi joints was investigated. Compared with conventional fusion welding techniques, no intermetallic compounds formed in the joints, which is extreme importance for this particular class of alloys. The joining mechanisms involve a combination of shear plastic deformation, mechanical interlocking and formation of micro-welds. A better bonding interface was obtained with higher welding energy levels, which contributed to a higher tensile load. An interfacial fracture mode occurred and the fracture surfaces exhibited both brittle and ductile-like characteristics with the existence of tear ridges and dimples. The fracture initiated at the weak region of the joint border and then propagated through it, leading to tearing of Cu foil at the fracture interface. Materials science ; Nickel titanium ; Shape-memory alloy ; Welding ; Tearing ; Spot welding ; Intermetallic ; Composite material ; Brittleness ; Interlocking ; Fracture (geology) ; Cold welding ; Martensite ; Ultrasonic welding ; FOIL method ; Metallurgy ; Microstructure ; Laser beam welding ; Structural engineering ; Alloy Shape Memory Alloy Transformations ; Advanced Welding Techniques Analysis ; Ultrasonics and Acoustic Wave Propagation
Authors: Eitam Vinegrad | Uri Hananel | Gil Markovich | Ori Cheshnovsky
Source: ACS Nano (article, 2018-12-06)
Field: Materials Science — Materials Chemistry

Determination of Handedness in a Single Chiral Nanocrystal <i>via</i> Circularly Polarized Luminescence The occurrence of biological homochirality is attributed to symmetry-breaking mechanisms which are still debatable. Studies of symmetry breaking require tools for monitoring the population ratios of individual chiral nano-objects, such as molecules, polymers, or nanocrystals. Moreover, mapping their spatial distributions may elucidate on their symmetry-breaking mechanism. While luminescence is preferred for detecting single particle chirality due to its high signal-to-noise ratio, the typical low optical activity of chromophores limits its applicability. Here, we report on handedness determination of single chiral lanthanide-based luminescent nanocrystals with a total photon count of 2 × 104. Due to the large emission dissymmetry, we could determine the handedness of individual particles using only a single circular polarization component of the emission spectrum, without polarization modulation. A machine learning algorithm, trained to several spectral line shape features, enabled us to determine and spatially map the handedness of individual nanocrystals with high accuracy and speed. This technique may become invaluable in studies of symmetry breaking in chiral materials. Luminescence ; Chirality (physics) ; Symmetry breaking ; Nanocrystal ; Chiral symmetry breaking ; Chromophore ; Homochirality ; Materials science ; Circular polarization ; Polarization (electrochemistry) ; Population ; Chemical physics ; Molecular physics ; Nanotechnology ; Optoelectronics ; Physics ; Optics ; Chemistry ; Quantum mechanics ; Physical chemistry ; Stereochemistry ; Enantiomer Luminescence and Fluorescent Materials ; Nanocluster Synthesis and Applications ; Molecular Sensors and Ion Detection
Authors: Botond Szilágyi | Zoltán K. Nagy
Source: Crystal Growth & Design (article, 2018-07-23)
Field: Materials Science — Materials Chemistry

Aspect Ratio Distribution and Chord Length Distribution Driven Modeling of Crystallization of Two-Dimensional Crystals for Real-Time Model-Based Applications Two-dimensional (2D) crystals, for which the shape is described by two linear sizes, are common in fine chemical and pharmaceutical industries. Since the crystal size and shape are directly related to the performance of active pharmaceutical ingredients, the simultaneous size and shape distribution control is of paramount importance in pharmaceutical crystallization engineering. To efficiently achieve simultaneous size and shape control often requires model-based control strategies; however, the increased computational cost of the process simulation and the substantial differences between the simulated and measurable quantities make the implementation of model-based control approaches challenging. This paper addresses the important problem of the real-time simulation of the most likely measurable chord length distribution (CLD) and aspect ratio distribution (ARD) as well as the concentration variations during the crystallization of 2D needle-shaped crystals. This enables the application of focused beam reflectance measurement (FBRM) and particle vision and microscopy (PVM), two routinely applied probes, as quantitative direct feedback control tools. Artificial neural network (ANN)-based FBRM and PVM soft-sensors are developed, which enable the direct and fast transformation of 2D crystal size distribution (CSD) to CLD and ARD on arbitrary 2D grids. The training data for the ANN are generated by a first principle, geometrical model-based simulation of FBRM and PVM for high aspect ratio crystals, although the ANN approach is applicable for any simulated or experimental training data sets. It is also demonstrated that the in situ imaging-based shape measurement underestimates the real aspect ratio (AR) of crystals, for which a simple correction is proposed. From the model-equation solution perspective, the soft-sensors require full population balance solution. The 2D high-resolution finite volume method is applied to simulate the full 2D CSD, which is an accurate, stable, but computationally expensive technique. The real-time applicability is achieved through various implementation improvements including grid optimization and data-type optimized hybrid central processing unit–graphical processing unit calculations. Crystallization ; Chord (peer-to-peer) ; Biological system ; Process (computing) ; Aspect ratio (aeronautics) ; Computer science ; Crystal (programming language) ; Artificial neural network ; Materials science ; Algorithm ; Optics ; Artificial intelligence ; Physics ; Engineering ; Optoelectronics ; Distributed computing ; Chemical engineering Crystallization and Solubility Studies ; Spectroscopy and Chemometric Analyses ; Enzyme Structure and Function
Authors: Shupei Xiao | Yong He | Tao Dong | Pengcheng Nie
Source: Sensors (article, 2018-02-09)
Field: Chemistry — Analytical Chemistry

Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors Compared with the chemical analytical technique, the soil nitrogen acquisition method based on near infrared (NIR) sensors shows significant advantages, being rapid, nondestructive, and convenient. Providing an accurate grasp of different soil types, sensitive wavebands could enhance the nitrogen estimation efficiency to a large extent. In this paper, loess, calcium soil, black soil, and red soil were used as experimental samples. The prediction models between soil nitrogen and NIR spectral reflectance were established based on three chemometric methods, that is, partial least squares (PLS), backward interval partial least squares (BIPLS), and back propagation neural network (BPNN). In addition, the sensitive wavebands of four kinds of soils were selected by competitive adaptive reweighted sampling (CARS) and BIPLS. The predictive ability was assessed by the coefficient of determination <i>R²</i> and the root mean square error (RMSE). As a result, loess ( 0.93 < R p 2 < 0.95 , 0.066 g / kg < RMSE p < 0.075 g / kg ) and calcium soil ( 0.95 < R p 2 < 0.96 , 0.080 g / kg < RMSE p < 0.102 g / kg ) achieved a high prediction accuracy regardless of which algorithm was used, while black soil ( 0.79 < R p 2 < 0.86 , 0.232 g / kg < RMSE p < 0.325 g / kg ) obtained a relatively lower prediction accuracy caused by the interference of high humus content and strong absorption. The prediction accuracy of red soil ( 0.86 < R p 2 < 0.87 , 0.231 g / kg < RMSE p < 0.236 g / kg ) was similar to black soil, partly due to the high content of iron-aluminum oxide. Compared with PLS and BPNN, BIPLS performed well in removing noise and enhancing the prediction effect. In addition, the determined sensitive wavebands were 1152 nm-1162 nm and 1296 nm-1309 nm (loess), 1036 nm-1055 nm and 1129 nm-1156 nm (calcium soil), 1055 nm, 1281 nm, 1414 nm-1428 nm and 1472 nm-1493 nm (black soil), 1250 nm, 1480 nm and 1680 nm (red soil). It is of great value to investigate the differences among the NIR spectral characteristics of different soil types and determine sensitive wavebands for the more efficient and portable NIR sensors in practical application. Mean squared error ; Partial least squares regression ; Nitrogen ; Soil water ; Chemistry ; Soil science ; Soil test ; Environmental science ; Mathematics ; Analytical Chemistry (journal) ; Environmental chemistry ; Statistics Spectroscopy and Chemometric Analyses ; Soil Geostatistics and Mapping ; Remote Sensing in Agriculture
Authors: Yen‐Ju Wu | Michiko Sasaki | Masahiro Goto | Lie Fang | Yibin Xu
Source: ACS Applied Nano Materials (article, 2018-07-03)
Field: Materials Science — Materials Chemistry

Electrically Conductive Thermally Insulating Bi–Si Nanocomposites by Interface Design for Thermal Management We demonstrate, both by experiments and by data informatics, an alternative strategy to achieve ultralow thermal conductivity in a dense solid. The interfacial thermal resistance (ITR) prediction of the machine learning model is implemented in a nanoscale field. The size dependence on ITR is considered and applied to the interface design of nanostructuring. The Bi/Si system was selected from 2025 kinds of interfaces through the interface thermal resistance prediction model by machine learning. The BiSi nanocomposite, which was composed of crystallized Bi and amorphous Si, was designed with various parameters by a laboratory-built combinatorial sputtering system. Electrically conductive, thermally insulating BiSi nanocomposites were reported for the first time and have a thermal conductivity as low as 0.16 W m–1 K–1. The ultralow thermal conductivity is attributed to the high ratio between the interfacial surface area and the volume because of the small Bi particle size and high Si/Bi atomic ratio. By introducing the informatics method, the potential candidates can be discovered and realized for thermoelectric applications. Materials science ; Thermal conductivity ; Nanocomposite ; Interfacial thermal resistance ; Thermal resistance ; Thermal ; Electrical conductor ; Thermal grease ; Composite material ; Thermal conduction ; Thermoelectric effect ; Nanotechnology ; Optoelectronics ; Thermodynamics Thermal properties of materials ; Advanced Thermoelectric Materials and Devices ; Machine Learning in Materials Science
Authors: S. Anbu Anjugam Vandarkuzhali | Karthikeyan Sekar | B. Viswanathan | M.P. Pachamuthu
Source: Surfaces and Interfaces (article, 2018-07-31)
Field: Chemistry — Organic Chemistry

Arachis hypogaea derived activated carbon/Pt catalyst: Reduction of organic dyes Catalysis ; Sodium borohydride ; Rhodamine B ; Congo red ; Materials science ; Activated carbon ; Xanthene ; Malachite green ; Nuclear chemistry ; Inorganic chemistry ; Chemistry ; Photocatalysis ; Photochemistry ; Organic chemistry ; Adsorption Nanomaterials for catalytic reactions ; Adsorption and biosorption for pollutant removal ; Graphene and Nanomaterials Applications