jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Eduardo D. Munaiz | Philip A. Townsend | Michael J. Havey
Source: Molecules (article, 2020-07-29)
Field: Chemistry — Analytical Chemistry

Reflectance Spectroscopy for Non-Destructive Measurement and Genetic Analysis of Amounts and Types of Epicuticular Waxes on Onion Leaves Epicuticular waxes on the surface of plant leaves are important for the tolerance to abiotic stresses and plant-parasite interactions. In the onion (<i>Allium cepa</i> L.), the variation for the amounts and types of epicuticular waxes is significantly associated with less feeding damage by the insect <i>Thrips tabaci</i> (thrips). Epicuticular wax profiles are measured using used gas chromatography mass spectrometry (GCMS), which is a labor intensive and relatively expensive approach. Biochemical spectroscopy is a non-destructive tool for measurement and analysis of physiological and chemical features of plants. This study used GCMS and full-range biochemical spectroscopy to characterize epicuticular waxes on seven onion accessions with visually glossy (low wax), semi-glossy (intermediate wax), or waxy (copious wax) foliage, as well as a segregating family from the cross of glossy and waxy onions. In agreement with previous studies, GCMS revealed that the three main waxes on the leaves of a wild type waxy onion were the ketone hentriacontanone-16 (H16) and fatty alcohols octacosanol-1 (Oct) and triacontanol-1 (Tri). The glossy cultivar "Odourless Greenleaf" had a unique phenotype with essentially no H16 and Tri and higher amounts of Oct and the fatty alcohol hexacosanol-1 (Hex). Hyperspectral reflectance profiles were measured on leaves of the onion accessions and segregating family, and partial least-squares regression (PLSR) was utilized to generate a spectral coefficient for every wavelength and prediction models for the amounts of the three major wax components. PLSR predictions were robust with independent validation coefficients of determination at 0.72, 0.70, and 0.42 for H16, Oct, and Tri, respectively. The predicted amounts of H16, Oct, and Tri are the result of an additive effect of multiple spectral features of different intensities. The variation of reflectance for H16, Oct, and Tri revealed unique spectral features at 2259 nm, 645 nm, and 730 nm, respectively. Reflectance spectroscopy successfully revealed a major quantitative trait locus (QTL) for amounts of H16, Oct, and Tri in the segregating family, agreeing with previous genetic studies. This study demonstrates that hyperspectral signatures can be used for non-destructive measurement of major waxes on onion leaves as a basis for rapid plant assessment in support of developing thrips-resistant onions. Wax ; Epicuticular wax ; Near infrared reflectance spectroscopy ; Reflectivity ; Spectroscopy ; Botany ; Chemistry ; Chromatography ; Biology ; Optics ; Near-infrared spectroscopy ; Organic chemistry ; Physics Spectroscopy and Chemometric Analyses ; Leaf Properties and Growth Measurement ; Postharvest Quality and Shelf Life Management
Authors: Gary Wan | Alex Croot | Neil A. Fox | Mattia Cattelan
Source: Advanced Functional Materials (article, 2020-10-15)
Field: Materials Science — Materials Chemistry

Empty‐State Band Mapping Using Momentum‐Resolved Secondary Electron Emission Abstract Material band structures of occupied electronic states are obtainable using conventional angle‐resolved photoemission experiments, leaving the unoccupied states far less explored. Here, an alternative approach is built on and expanded to investigate thermalized photoelectrons emitted from crystal surfaces. A model for electron emission is constructed and reveals the material unoccupied state band structure. Potentially applicable to any material and independent from the secondary electron generation mechanism, it is demonstrated on diamond and copper using different light sources. Moreover, the diamond indirect band gap is directly observed and the transverse effective mass at the conduction band minimum can be experimentally obtained, m t = (0.21 ± 0.015) m e . This offers a convenient path for angle‐resolved photoemission data interpretation and empty‐state information extraction. Materials science ; Secondary emission ; Diamond ; Photoelectric effect ; Electronic band structure ; Band gap ; Electron ; Quasi Fermi level ; Atomic physics ; Inverse photoemission spectroscopy ; Electronic structure ; Effective mass (spring–mass system) ; Angle-resolved photoemission spectroscopy ; Condensed matter physics ; Direct and indirect band gaps ; Optoelectronics ; Physics Electronic and Structural Properties of Oxides ; Semiconductor materials and devices ; Diamond and Carbon-based Materials Research
Authors: Najmeh Keshtkar | Klaus Röbenack
Source: Algorithms (article, 2020-01-15)
Field: Materials Science — Materials Chemistry

Unstructured Uncertainty Based Modeling and Robust Stability Analysis of Textile-Reinforced Composites with Embedded Shape Memory Alloys This paper develops the mathematical modeling and deflection control of a textile-reinforced composite integrated with shape memory actuators. The mathematical model of the system is derived using the identification method and an unstructured uncertainty approach. Based on this model and a robust stability analysis, a robust proportional–integral controller is designed for controlling the deflection of the composite. We showed that the robust controller depends significantly on the modeling of the uncertainty. The performance of the proposed controller is compared with a classical one through experimental analysis. Experimental results show that the proposed controller has a better performance as it reduces the overshoot and provide robustness to uncertainty. Due to the robust design, the controller also has a wide operating range, which is advantageous for practical applications. Robustness (evolution) ; Actuator ; Deflection (physics) ; Control theory (sociology) ; Robust control ; Computer science ; System identification ; Control system ; Artificial intelligence ; Engineering ; Data modeling ; Control (management) ; Physics Shape Memory Alloy Transformations ; Polymer composites and self-healing ; Structural Analysis and Optimization
Authors: Chiara Martinelli
Source: Anti-Cancer Agents in Medicinal Chemistry (review, 2020-06-20)
Field: Materials Science — Biomaterials

Smart Nanocarriers for Targeted Cancer Therapy Cancer is considered one of the most threatening diseases worldwide. Although many therapeutic approaches have been developed and optimized for ameliorating patient's conditions and life expectancy, however, it frequently remains an incurable pathology. Notably, conventional treatments may reveal inefficient in the presence of metastasis development, multidrug resistance and inability to achieve targeted drug delivery. In the last decades, nanomedicine has gained a prominent role, due to many properties ascribable to nanomaterials. It is worth mentioning their small size, their ability to be loaded with small drugs and bioactive molecules and the possibility to be functionalized for tumor targeting. Natural vehicles have been exploited, such as exosomes, and designed, such as liposomes. Biomimetic nanomaterials have been engineered, by modification with biological membrane coating. Several nanoparticles have already entered clinical trials and some liposomal formulations have been approved for therapeutic applications. In this review, natural and synthetic nanocarriers functionalized for actively targeting cancer cells will be described, focusing on their advantages with respect to conventional treatments. Recent innovations related to biomimetic nanoparticles camouflaged with membranes isolated from different types of cells will be reported, together with their promising applications. Finally, a short overview on the latest advances in carrier-free nanomaterials will be provided. Nanocarriers ; Cancer therapy ; Cancer ; Medicine ; Nanotechnology ; Materials science ; Drug delivery ; Internal medicine Nanoparticle-Based Drug Delivery ; Advanced biosensing and bioanalysis techniques ; Nanoplatforms for cancer theranostics
Authors: Tomáš Urbánek | Jiří Trousil | Dmytro Rak | Kristýna Gunár | Rafał Konefał | Miroslav Šlouf | Marián Sedlák | Olga Janoušková | Martin Hrubý
Source: Macromolecular Bioscience (article, 2020-03-16)
Field: Materials Science — Biomaterials

γ‐Butyrolactone Copolymerization with the Well‐Documented Polymer Drug Carrier Poly(ethylene oxide)‐<i>block</i>‐poly(ε‐caprolactone) to Fine‐Tune Its Biorelevant Properties Polymeric drug carriers exhibit excellent properties that advance drug delivery systems. In particular, carriers based on poly(ethylene oxide)-block-poly(ε-caprolactone) are very useful in pharmacokinetics. In addition to their proven biocompatibility, there are several requirements for the efficacy of the polymeric drug carriers after internalization, e.g., nanoparticle behavior, cellular uptake, the rate of degradation, and cellular localization. The introduction of γ-butyrolactone units into the hydrophobic block enables the tuning of the abovementioned properties over a wide range. In this study, a relatively high content of γ-butyrolactone units with a reasonable yield of ≈60% is achieved by anionic ring-opening copolymerization using 1,5,7-triazabicyclo[4.4.0]dec-5-ene as a very efficient catalyst in the nonpolar environment of toluene with an incorporated γ-butyrolactone content of ≈30%. The content of γ-butyrolactone units can be easily modulated according to the feed ratio of the monomers. This method enables control over the rate of degradation so that when the content of γ-butyrolactone increases, the rate of degradation increases. These findings broaden the application possibilities of polyester-polyether-based nanoparticles for biomedical applications, such as drug delivery systems. Copolymer ; Ethylene oxide ; Chemistry ; Polymer ; Monomer ; Biocompatibility ; Polyester ; Drug delivery ; Polymer chemistry ; Ethylene ; Caprolactone ; Toluene ; Nanoparticle ; Chemical engineering ; Drug carrier ; Materials science ; Catalysis ; Organic chemistry ; Nanotechnology biodegradable polymer synthesis and properties ; Advanced Polymer Synthesis and Characterization ; Electrospun Nanofibers in Biomedical Applications
Authors: Dao Zhang | Jueqin Yu
Source: Organometallics (article, 2020-04-16)
Field: Chemistry — Organic Chemistry

Fine Tuning of Chiral Bis(N-heterocyclic carbene) Palladium Catalysts for Asymmetric Suzuki–Miyaura Cross-Coupling Reactions: Exploring the Ligand Modification Novel chiral N,N′-bisaryl bis(NHC) ligand precursors H2[(S)-2]Cl2 on a spiro scaffold and H2[(S)-3b–g]Cl2 with a binaphthyl linkage were rationally designed and their cyclometalated cis-chelated NHC palladium complexes (S)-5, (S)-6, and (S)-7b–g have been synthesized and fully characterized. Complexes 6 and 7b were further confirmed by X-ray single-crystal analysis. Both complexes adopted a slightly distorted square planar geometry around the Pd(II) center. The structure of 6 consists of a rare dimeric arrangement incorporating two palladium(II) centers bonded through a short metal–metal bond (2.853(2) Å), indicating a PdII–PdII intramolecular interaction (<3.00 Å). These N,N′-bisaryl-bis(NHC)-Pd complexes together with N,N′-bisalkyl analogues {[(S)-1a–d]PdX2} (X = I, (S)-4a; X = Br, (S)-4b–d) have been used in the asymmetric aryl–aryl cross-coupling reactions of arylboronic acids and aryl halides. The enantioselectivity of the biaryl products was greatly improved within 24 h (up to 74% ee) when complexes 7a–g were used as catalysts. The results show that for these types of bis(NHC) palladium catalysts the structural characters of the chiral scaffolds play a decisive role in the enantioselectivities of cross-coupling reactions. Chemistry ; Palladium ; Aryl ; Intramolecular force ; Ligand (biochemistry) ; Carbene ; Catalysis ; Coupling reaction ; Halide ; Stereochemistry ; Medicinal chemistry ; Metal ; Organic chemistry Catalytic Cross-Coupling Reactions ; N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Axial and Atropisomeric Chirality Synthesis
Authors: Anamika Chaturvedi | Pranjali Pranjali | Mukesh Kumar Meher | Ritu Raj | Madhuri Basak | Ranjan K. Singh | Krishna Mohan Poluri | Dinesh Kumar | Anupam Guleria
Source: Journal of Applied Physics (article, 2020-07-16)
Field: Materials Science — Biomaterials

<i>In vitro</i> and <i>ex vivo</i> relaxometric properties of ethylene glycol coated gadolinium oxide nanoparticles for potential use as contrast agents in magnetic resonance imaging Magnetic nanoparticles (MNPs) have widely demonstrated their applicability in many biomedical applications including magnetic resonance imaging (MRI), hyperthermia, and drug delivery. However, the effectiveness of MNPs can be limited for in vivo applications due to their hydrophobic surfaces leading to nanoparticle agglomeration and thus requires appropriate surface modification to enhance colloidal stability. Glycols are widely used coating material for surface modifications of MNPs to improve their physicochemical properties and biocompatibility. The present work reports the preparation of two different sized ethylene glycol coated gadolinium oxide nanoparticles (EG@Gd2O3 NPs) using two different synthesis approaches and their applicability as contrast agents in MRI. Thermo-gravimetric analysis and Fourier transform infrared spectroscopy confirmed the successful coating of ethylene glycol on the surface of NPs. We found that independent of the size of NPs, the globular shaped EG@Gd2O3 NPs exhibited similar crystal structures, magnetic properties, and cellular cytotoxicity behavior. However, a significant impact of size on MRI contrast enhancement properties was seen. It was revealed that the relaxivity of EG@Gd2O3 NPs increases with a decrease in particle size. Small sized EG@Gd2O3 NPs (∼12 nm) exhibited a high specific in vitro and ex vivo longitudinal relaxivity of 3.7 and 1.5 mM−1 s−1, respectively, thus clearly elucidating the potential of these NPs for use as local contrast enhancement agents. The present study gives insights into the intrinsic dependence of magnetic resonance contrast effects of NPs on particle size and surface coating layer mass ratio and thus demonstrates the development of efficient magnetic nanoparticles based contrast agents by fine tuning of particle size and surface properties. Ethylene glycol ; Nanoparticle ; Biocompatibility ; Magnetic nanoparticles ; Gadolinium ; Materials science ; Chemical engineering ; MRI contrast agent ; Nanotechnology ; Drug delivery ; Particle size ; Nanomedicine ; Surface modification ; Coating Nanoparticle-Based Drug Delivery ; Lanthanide and Transition Metal Complexes ; Characterization and Applications of Magnetic Nanoparticles
Authors: Nur Zehan An’nisa Md Shah | Marlia Morsin | Rahmat Sanudin | Nur Liyana Razali | Suratun Nafisah | Chin Fhong Soon
Source: Plasmonics (article, 2020-01-03)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Effects of Growth Solutions Ageing Time to the Formation of Gold Nanorods via Two-Step Approach for Plasmonic Applications Nanorod ; Materials science ; Surface plasmon resonance ; Plasmon ; Aspect ratio (aeronautics) ; Nanotechnology ; Ageing ; Substrate (aquarium) ; Resonance (particle physics) ; Optoelectronics ; Nanoparticle Gold and Silver Nanoparticles Synthesis and Applications ; Plasmonic and Surface Plasmon Research ; Nanocluster Synthesis and Applications
Authors: Patrick N. Charron | Jaime I. Jacobs | Selina X. Yao | Rachael Floreani
Source: Biointerphases (article, 2020-09-01)
Field: Materials Science — Biomaterials

Effects of cryo-processing on the mechanical and biological properties of poly(vinyl alcohol)-gelatin theta-gels Poly(vinyl alcohol) (PVA), a synthetic, nontoxic polymer, is widely studied for use as a biomedical hydrogel due to its structural and physicomechanical properties. Depending on the synthesis method, PVA hydrogels can exhibit a range of selected characteristics-strength, creep resistance, energy dissipation, degree of crystallinity, and porosity. While the structural integrity and behavior of the hydrogel can be fine-tuned, common processing techniques result in a brittle, linear elastic material. In addition, PVA lacks functionality to engage and participate in cell adhesion, which can be a limitation for integrating PVA materials with tissue in situ. Thus, there is a need to further engineer PVA hydrogels to optimize its physicomechanical properties while enhancing cell adhesion and bioactivity. While the inclusion of gelatin into PVA hydrogels has been shown to impart cell-adhesive properties, the optimization of the mechanical properties of PVA-gelatin blends has not been studied in the context of traditional PVA hydrogel processing techniques. The incorporation of poly(ethylene glycol) with PVA prior to solidification forms an organized, cell instructive hydrogel with improved stiffness. The effect of cryo-processing, i.e., freeze-thaw (FT) cycling was elucidated by comparing 1 FT and 8 FT theta-cryo-gels and cryo-gels. To confirm the viability of the gels, human mesenchymal stem cell (hMSC) protein and sulfated glycosaminoglycan assays were performed to verify the nontoxicity and influence on hMSC differentiation. We have devised an elastic PVA-gelatin hydrogel utilizing the theta-gel and cryo-gel processing techniques, resulting in a stronger, more elastic material with greater potential as a scaffold for complex tissues. Vinyl alcohol ; Gelatin ; Self-healing hydrogels ; Materials science ; Ethylene glycol ; Polymer ; Polyvinyl alcohol ; Crystallinity ; Chemical engineering ; Adhesion ; Composite material ; Polymer chemistry ; Chemistry Electrospun Nanofibers in Biomedical Applications ; Hydrogels: synthesis, properties, applications ; 3D Printing in Biomedical Research
Authors: Sophie Schönfeld | Wolfgang Bauer | Sebastian Thallmair | Gerald Hörner | Birgit Weber
Source: Zeitschrift für anorganische und allgemeine Chemie (article, 2020-12-03)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Running in the Family: Molecular Factors controlling Spin Crossover of Iron(II) Complexes with Schiff‐base like Ligands Abstract Tailoring of spin state energetics of transition metal complexes and even the correct prediction of the resulting spin state is still a challenging task, both for the experimentalist and the theoretician. Apart from the complexity in the solid state imposed by packing effects, molecular factors of the spin state ordering are required to be identified and quantified on equal rights. In this work we experimentally record the spin states and SCO energies within an eight‐member substitution‐series of N 4 O 2 ligated iron(II) complexes both in the solid state (SQUID magnetometry and single‐crystal X‐ray crystallography) and in solution (VT‐NMR). The experimental survey is complemented by exhaustive theoretical modelling of the molecular and electronic structure of the open‐chain N 4 O 2 family and its macrocyclic N 6 congeners through density‐functional theory methods. Ligand topology is identified as the leading factor defining ground‐state multiplicity of the corresponding iron(II) complexes. Invariably the low‐spin state is sterically trapped in the macrocycles, whereas subtle substitution effects allow for a molecular fine tuning of the spin state in the open‐chain ligands. Factorization of computed relative SCO energies holds promise for directed design of future SCO systems. Spin crossover ; Spin states ; Schiff base ; Chemistry ; Crystallography ; Steric effects ; Density functional theory ; Ligand (biochemistry) ; Homologous series ; Chemical physics ; Computational chemistry ; Topology (electrical circuits) ; Stereochemistry ; Inorganic chemistry ; Mathematics ; Combinatorics Magnetism in coordination complexes ; Metal-Catalyzed Oxygenation Mechanisms ; Metal complexes synthesis and properties
Authors: Yi‐Qi Yeh | Chun‐Jen Su | Chen-An Wang | Ying-Chu Lai | Chih‐Yuan Tang | Zhenyu Di | Henrich Frielinghaus | An‐Chung Su | U‐Ser Jeng | Chung‐Yuan Mou
Source: Journal of Colloid and Interface Science (article, 2020-11-03)
Field: Materials Science — Biomaterials

Diatom-inspired self-assembly for silica thin sheets of perpendicular nanochannels With fine-tuned molar ratios of the anionic, cationic, and nonionic surfactants, the catanionic combination and the nonionic copolymer form charged, prolate ternary micelles in aqueous solutions, which further develop into prototype monolayered micellar plates. The prolate shape and maximized surfactant adsorption of the complex micelles, revealed from combined SAXS/SANS analysis, are of critical importance in the subsequent micellar self-assembly upon silicate deposition. Time-resolved SAXS and FFR-TEM indicate that the silicate complex micelles coalesce laterally into the prototype micellar nanoplates, which further fuse with one another into large sheets of monolayered silicate micelles of in-plane lamellar packing. Upon silica polymerization, the in-plane lamellar packing of the micelles further transforms to 2D hexagonal packing of vertically oriented silicate channels. The unveiled structural features and their evolution not only elucidate the previously unresolved self-assembly process of through-thickness silica nanochannels but also open a new line of research mimicking free-standing frustules of diatoms. Micelle ; Small-angle X-ray scattering ; Chemical engineering ; Materials science ; Lamellar structure ; Silicate ; Copolymer ; Sodium silicate ; Aqueous solution ; Chemistry ; Composite material ; Organic chemistry ; Scattering ; Optics ; Polymer Diatoms and Algae Research ; Mesoporous Materials and Catalysis ; Paleontology and Stratigraphy of Fossils
Authors: Carlos Figueroa | Víctor H. Jacobo | Jacinto Cortés‐Pérez | Rafael Schouwenaars
Source: Materials (article, 2020-12-14)
Field: Materials Science — Materials Chemistry

Surface Nanostructuring of a CuAlBe Shape Memory Alloy Produces a 10.3 ± 0.6 GPa Nanohardness Martensite Microstructure Severe plastic deformation (SPD) has led to the discovery of ever stronger materials, either by bulk modification or by surface deformation under sliding contact. These processes increase the strength of an alloy through the transformation of the deformation substructure into submicrometric grains or twins. Here, surface SPD was induced by plastic deformation under frictional contact with a spherical tool in a hot rolled CuAlBe-shape memory alloy. This created a microstructure consisting of a few course martensite variants and ultrafine intersecting bands of secondary martensite and/or austenite, increasing the nanohardness of hot-rolled material from 2.6 to 10.3 GPa. In as-cast material the increase was from 2.4 to 5 GPa. The friction coefficient and surface damage were significantly higher in the hot rolled condition. Metallographic evidence showed that hot rolling was not followed by recrystallisation. This means that a remaining dislocation substructure can lock the martensite and impedes back-transformation to austenite. In the as-cast material, a very fine but softer austenite microstructure was found. The observed difference in properties provides an opportunity to fine-tune the process either for optimal wear resistance or for maximum surface hardness. The modified hot-rolled material possesses the highest hardness obtained to date in nanostructured non-ferrous alloys. Materials science ; Microstructure ; Austenite ; Martensite ; Metallurgy ; Alloy ; Substructure ; Deformation (meteorology) ; Dislocation ; Shape-memory alloy ; Diffusionless transformation ; Composite material Microstructure and mechanical properties ; Metal and Thin Film Mechanics ; Titanium Alloys Microstructure and Properties