jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Qunpeng Duan | Yibo Xing | Kainan Guo
Source: Frontiers in Chemistry (article, 2021-12-21)
Field: Chemistry — Spectroscopy

Carboxylato-Pillar[6]arene-Based Fluorescent Indicator Displacement Assays for Caffeine Sensing In the present work, we have developed a new indicator displacement system based on pillararene for anionic water-soluble carboxylato pillar [6] arene (WP6) and aromatic fluorescent dye safranine T (ST). A large fluorescence enhancement and colour change of ST were observed after complexation with electron-rich cavity in WP6 because of host-guest twisted intramolecular charge-transfer interactions. The constructed pillararene-indicator displacement system can be applied for caffeine selective detection in water. Fluorescence ; Pillar ; Displacement (psychology) ; Chemistry ; Intramolecular force ; Photochemistry ; Stereochemistry ; Optics Molecular Sensors and Ion Detection ; Luminescence and Fluorescent Materials ; Supramolecular Chemistry and Complexes
Authors: Rashmi Mannu | Vaithinathan Karthikeyan | M. V. Murugendrappa | Vellaisamy A. L. Roy | A. Gopalan | Gopalan Saianand | Prashant Sonar | Binrui Xu | Yi‐Chia Lee | Wha-Jung Kim | Dong‐Eun Lee | K. Venkatramanan
Source: International Journal of Environmental Research and Public Health (article, 2021-03-15)
Field: Chemistry — Organic Chemistry

Facile Use of Silver Nanoparticles-Loaded Alumina/Silica in Nanofluid Formulations for Enhanced Catalytic Performance toward 4-Nitrophenol Reduction The introduction of toxic chemicals into the environment can result in water pollution leading to the degradation of biodiversity as well as human health. This study presents a new approach of using metal oxides (Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub>) modified with a plasmonic metal (silver, Ag) nanoparticles (NPs)-based nanofluid (NF) formulation for environmental remediation purposes. Firstly, we prepared the Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> NFs of different concentrations (0.2 to 2.0 weight %) by ultrasonic-assisted dispersion of Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> NPs with water as the base fluid. The thermo-physical (viscosity, activation energy, and thermal conductivity), electrical (AC conductivity and dielectric constant) and physical (ultrasonic velocity, density, refractive index) and stability characteristics were comparatively evaluated. The Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> NPs were then catalytically activated by loading silver NPs to obtain Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub>@Ag composite NPs. The catalytic reduction of 4-nitrophenol (4-NP) with Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub>@Ag based NFs was followed. The catalytic efficiency of Al<sub>2</sub>O<sub>3</sub>@Ag NF and SiO<sub>2</sub>@Ag NF, for the 4-NP catalysis, is compared. Based on the catalytic rate constant evaluation, the catalytic reduction efficiency for 4-NP is found to be superior for 2% weight Al<sub>2</sub>O<sub>3</sub>@Ag NF (92.9 × 10<sup>-3</sup> s<sup>-1</sup>) as compared to the SiO<sub>2</sub>@Ag NF (29.3 × 10<sup>-3</sup> s<sup>-1</sup>). Importantly, the enhanced catalytic efficiency of 2% weight Al<sub>2</sub>O<sub>3</sub>@Ag NF for 4-NP removal is much higher than other metal NPs based catalysts reported in the literature, signifying the importance of NF formulation-based catalysis. Catalysis ; Chemical engineering ; Nanoparticle ; Materials science ; 4-Nitrophenol ; Silver nanoparticle ; Nanocomposite ; Dispersion (optics) ; Reaction rate constant ; Nanofluid ; Selective catalytic reduction ; Thermal stability ; Nanotechnology ; Chemistry ; Kinetics ; Organic chemistry Nanomaterials for catalytic reactions ; Copper-based nanomaterials and applications ; Solar-Powered Water Purification Methods
Authors: Harshil Dhruv
Source: Digital Commons - USU (Utah State University) (article, 2021-09-30)
Field: Materials Science — Biomaterials

Controlling Nonspecific Adsorption of Proteins at Bio-Interfaces for Biosensor and Biomedical Applications Partitioning of poly(ethyleneglycol) (PEG) molecules in 2-D and 3-D systems is presented as a self-assembly approach for controlling non-specific adsorption of proteins at interfaces. Lateral restructuring of multi-component Langmuir monolayers to accommodate adsorbing proteins was investigated as a model 2-D system. Ferritin adsorption to monolayers containing cationic, nonionic, and PEG bearing phospholipids induced protein sized binding pockets surrounded by PEG rich regions. The number, size, and distribution of protein imprint sites were controlled by the molar ratios, miscibility, and lateral mobility of the lipids. The influence of PEG chain length on the ternary monolayer restructuring and protein distribution was also investigated using DSPE-PEGx (x= 7, 16, 22). Monolayer miscibility analysis demonstrated that longer PEG chains diminished the condensed phase formation for a fixed ratio of lipids. Thus, incorporation of longer PEG chains, intended to diminish protein adsorption outside of the imprint sites of cationic / non-ionic lipids, leads to dramatic changes in monolayer phase behavior and protein distribution in this 2-D system. The assembly of PEG-amphiphiles at elastomer surfaces and subsequent protein adsorption was investigated as a model 3-D system. Polydimethylsiloxane (PDMS) substrates were modified with block copolymers comprised of PEG and PDMS segments by two methods: (1) the block copolymer was mixed with PDMS during polymerization; (2) the block copolymer diffused into solvent swollen PDMS monoliths. Hydrophilic surfaces resulted for both approaches that, for 600 D block copolymer, exhibited up to 85% reduction in fibrinogen adsorption as compared to native PDMS. Higher MW block copolymers (up to 3000 D) resulted in less hydrophilic surfaces and greater protein adsorption, presumably due to diffusion limitations of copolymer in the PDMS monolith. All modified PDMS surfaces were dynamic and restructured when cycled between air and water. PDMS transparency also decreased with increase in block copolymer concentration for both methods, limiting this modification protocol for applications requiring high polymer transparency. The 2-D system presents a bottom-up approach, where adsorbing protein constructs the binding site, while the 3-D system presents a top down approach, where protein-binding elements may be introduced into the PEG-bearing polymer for fabrication of surfaces with controlled protein adsorption. Biosensor ; Adsorption ; Protein adsorption ; Chemistry ; Nanotechnology ; Biophysics ; Biochemical engineering ; Computational biology ; Biochemistry ; Biology ; Materials science ; Engineering Supramolecular Self-Assembly in Materials ; Molecular Junctions and Nanostructures ; Advanced biosensing and bioanalysis techniques
Authors: Nemrud Demirel | Jie Qin | Sergei I. Ivlev | Klaus Harms | Eric Meggers
Source: Advanced Synthesis & Catalysis (article, 2021-08-25)
Field: Chemistry — Organic Chemistry

Catalytic Enantioselective Oxidative Homocoupling of 2‐Acyl Imidazoles Abstract A diastereoselective and enantioselective construction of 2,3‐disubstituted 1,4‐dicarbonyl compounds is reported. Nishiyama's RuPhebox complex (2.0 mol% catalyst loading) serves as a chiral Lewis acid catalyst in conjunction with BrCCl 3 and a base for the oxidative homocoupling of 2‐acyl imidazoles via the stereocontrolled reaction of intermediate Ru enolates with in situ brominated 2‐acyl imidazoles. Cleavage of the achiral imidazole auxiliary provides optically active 2,3‐disubstituted succinic acids which are useful intermediates in the synthesis of chiral compounds like the natural product class of lignans. magnified image Chemistry ; Enantioselective synthesis ; Oxidative cleavage ; Catalysis ; Imidazole ; Organic chemistry ; Oxidative phosphorylation ; Lewis acids and bases ; Combinatorial chemistry ; Stereochemistry Catalytic C–H Functionalization Methods ; Oxidative Organic Chemistry Reactions ; Traditional and Medicinal Uses of Annonaceae
Authors: Devindraan S O Sirkkunan | Farina Muhamad | Belinda Pingguan‐Murphy
Source: Gels (article, 2021-09-27)
Field: Materials Science — Biomaterials

Application of “Magnetic Anchors” to Align Collagen Fibres for Axonal Guidance The use of neural scaffolds with a highly defined microarchitecture, fabricated with standard techniques such as electrospinning and microfluidic spinning, requires surgery for their application to the site of injury. To circumvent the risk associated with aciurgy, new strategies for treatment are sought. This has led to an increase in the quantity of research into injectable hydrogels in recent years. However, little research has been conducted into controlling the building blocks within these injectable hydrogels to produce similar scaffolds with a highly defined microarchitecture. "Magnetic particle string" and biomimetic amphiphile self-assembly are some of the methods currently available to achieve this purpose. Here, we developed a "magnetic anchor" method to improve the orientation of collagen fibres within injectable 3D scaffolds. This procedure uses GMNP (gold magnetic nanoparticle) "anchors" capped with CMPs (collagen mimetic peptides) that "chain" them to collagen fibres. Through the application of a magnetic field during the gelling process, these collagen fibres are aligned accordingly. It was shown in this study that the application of CMP functionalised GMNPs in a magnetic field significantly improves the alignment of the collagen fibres, which, in turn, improves the orientation of PC12 neurites. The growth of these neurite extensions, which were shown to be significantly longer, was also improved. The PC12 cells grown in collagen scaffolds fabricated using the "magnetic anchor" method shows comparable cellular viability to that of the untreated collagen scaffolds. This capability of remote control of the alignment of fibres within injectable collagen scaffolds opens up new strategic avenues in the research for treating debilitating neural tissue pathologies. Self-healing hydrogels ; Materials science ; Electrospinning ; Magnetic nanoparticles ; Nanotechnology ; Biomedical engineering ; Tissue engineering ; Neural tissue engineering ; Neurite ; Nanoparticle ; Polymer ; Chemistry ; Composite material ; Polymer chemistry ; In vitro Electrospun Nanofibers in Biomedical Applications ; Nerve injury and regeneration ; Bone Tissue Engineering Materials
Authors: Rui Cheng | Jingwen Li | Ioatzin Ríos de Anda | Thomas W. C. Taylor | Malcolm A. Faers | J. L. Ross Anderson | Annela M. Seddon | C. Patrick Royall
Source: The Journal of Chemical Physics (article, 2021-09-15)
Field: Materials Science — Materials Chemistry

Protein–polymer mixtures in the colloid limit: Aggregation, sedimentation, and crystallization While proteins have been treated as particles with a spherically symmetric interaction, of course in reality, the situation is rather more complex. A simple step toward higher complexity is to treat the proteins as non-spherical particles and that is the approach we pursue here. We investigate the phase behavior of the enhanced green fluorescent protein (eGFP) under the addition of a non-adsorbing polymer, polyethylene glycol. From small angle x-ray scattering, we infer that the eGFP undergoes dimerization and we treat the dimers as spherocylinders with aspect ratio L/D - 1 = 1.05. Despite the complex nature of the proteins, we find that the phase behavior is similar to that of hard spherocylinders with an ideal polymer depletant, exhibiting aggregation and, in a small region of the phase diagram, crystallization. By comparing our measurements of the onset of aggregation with predictions for hard colloids and ideal polymers [S. V. Savenko and M. Dijkstra, J. Chem. Phys. 124, 234902 (2006) and Lo Verso et al., Phys. Rev. E 73, 061407 (2006)], we find good agreement, which suggests that the behavior of the eGFP is consistent with that of hard spherocylinders and ideal polymers. Colloid ; Crystallization ; Phase (matter) ; Polymer ; Ideal (ethics) ; Work (physics) ; Fluorescence Material Dynamics and Properties ; Enzyme Structure and Function ; Polymer Surface Interaction Studies
Authors: Claire Meyer | Patrick Davidson | Doru Constantin | V. Sergan | D Stoenescu | Anamarija Knežević | Irena Dokli | Andreja Lesac | I. Dozov
Source: Physical Review X (article, 2021-07-16)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Fréedericksz-Like Transition in a Biaxial Smectic-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math> Phase The two main classes of liquid-crystal (LC) phases of rodlike molecules are nematics, where the rods align in the same direction (the nematic director n), and smectics, where the rods not only are aligned but also form layers. The electro-optic effects in LC devices that are a backbone in today's display industry mainly use the Fredericksz transition, which is the bulk reorientation of a surface-anchored nematic by an electric field. Conventional (uniaxial) smectics do not present a Fredericksz transition, because, due to their layered structure, the director reorientation would distort the layers, which would cost too much energy. In a worldwide ongoing effort to extend the variety of LC compounds suitable for applications in the display industry, bent-shaped molecules have recently raised much attention, since they present multiple new LC phases with unusual properties. In this paper, we report on a structural and electro-optic study of the LC phases of a bent-shaped dimer. On cooling from the isotropic liquid, this compound shows a usual nematic (N), a twist-bend nematic (N TB ), and a biaxial smectic-A phase (SmA b ). Quite surprisingly, contrary to usual smectics, SmA b presents a remarkable electro-optic response, with low (<4 V) voltage threshold, no reorganization of the smectic layers, and low (<1 ms) response time (i.e., 30 times faster than the N phase at higher temperature). We interpret this unexpected electro-optic effect as a Fredericksz transition affecting the secondary director m of the SmA b , and we model it by analogy with the usual Fredericksz transition of the n director of the uniaxial N phase. Indeed, a Fredericksz transition affecting only m in this biaxial fluid smectic does not alter its layered structure and costs little energy. From the point of view of applications, thanks to its low relaxation time, this "biaxial" Fredericksz transition could be exploited in electro-optic devices that require fast switching. Phase transition ; Combinatorics ; Mathematics ; Physics ; Condensed matter physics Liquid Crystal Research Advancements ; Advanced Materials and Mechanics ; Nonlinear Dynamics and Pattern Formation
Authors: Giulia Mazzoccanti | Francesco Gasparrini | Andrea Calcaterra | Claudio Villani | Alessia Ciogli
Source: Separations (article, 2021-05-02)
Field: Chemistry — Spectroscopy

Static vs. Dynamic Electrostatic Repulsion Reversed Phase Liquid Chromatography: Solutions for Pharmaceutical and Biopharmaceutical Basic Compounds Many efforts have been made to separate basic compounds, which are challenging to resolve in reversed phase liquid chromatography. In this process, they are strongly retained and the peak shape undergoes significant distortion. The principal origin of this has been identified with the non-negligible interaction with residual deprotonated silanols. Consequently, all solutions that efficiently shield silanols are being sought. This review is an upgrade on the use of the electrostatic repulsion reversed phase (ERRP) approach: retention of bases, in protonated form, can be achieved by modulating the charge repulsion caused by the presence of positive charges in the chromatographic system. This study successfully (i) introduced fixed positive charges in the structure of stationary phases, (ii) used cationic and hydrophobic additives in the mobile phase, and (iii) used the ERRP-like approach employed at the preparative level for peptide purification. Chemistry ; Deprotonation ; Protonation ; Cationic polymerization ; Phase (matter) ; Chromatography ; Biopharmaceutical ; Electrostatics ; Reversed-phase chromatography ; Electrostatic interaction ; Combinatorial chemistry ; High-performance liquid chromatography ; Chemical physics ; Organic chemistry ; Ion ; Physical chemistry Analytical Chemistry and Chromatography ; Protein purification and stability ; Chromatography in Natural Products
Authors: Amer Baniodeh | Danny Wagner | Yan Peng | Hagen Kaemmerer | Nicolas Leblanc | Stefan Bräse | Jean‐Valère Naubron | Christopher E. Anson | Annie K. Powell
Source: Chemistry - A European Journal (article, 2021-10-08)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Breaking Symmetry Relaxes Structural and Magnetic Restraints, Suppressing QTM in Enantiopure Butterfly Fe<sub>2</sub>Dy<sub>2</sub> SMMs** The {Fe<sub>2</sub> Dy<sub>2</sub> } butterfly systems can show single molecule magnet (SMM) behaviour, the nature of which depends on details of the electronic structure, as previously demonstrated for the [Fe<sub>2</sub> Dy<sub>2</sub> (μ<sub>3</sub> -OH)<sub>2</sub> (Me-teaH)<sub>2</sub> (O<sub>2</sub> CPh)<sub>6</sub> ] compound, where the [N,N-bis-(2-hydroxyethyl)-amino]-2-propanol (Me-teaH<sub>3</sub> ) ligand is usually used in its racemic form. Here, we describe the consequences for the SMM properties by using enantiopure versions of this ligand and present the first homochiral 3d/4 f SMM, which could only be obtained for the S enantiomer of the ligand for [Fe<sub>2</sub> Dy<sub>2</sub> (μ<sub>3</sub> -OH)<sub>2</sub> (Me-teaH)<sub>2</sub> (O<sub>2</sub> CPh)<sub>6</sub> ] since the R enantiomer underwent significant racemisation. To investigate this further, we prepared the [Fe<sub>2</sub> Dy<sub>2</sub> (μ<sub>3</sub> -OH)<sub>2</sub> (Me-teaH)<sub>2</sub> (O<sub>2</sub> CPh)<sub>4</sub> (NO<sub>3</sub> )<sub>2</sub> ] version, which could be obtained as the RS-, R- and S-compounds. Remarkably, the enantiopure versions show enhanced slow relaxation of magnetisation. The use of the enantiomerically pure ligand suppresses QTM, leading to the conclusion that use of enantiopure ligands is a "gamechanger" by breaking the cluster symmetry and altering the intimate details of the coordination cluster's molecular structure. Enantiopure drug ; Ligand (biochemistry) ; Enantiomer ; Crystallography ; Magnetization ; Cluster (spacecraft) ; Relaxation (psychology) ; Chemistry ; Molecule ; Stereochemistry ; Materials science ; Physics ; Magnetic field ; Organic chemistry ; Enantioselective synthesis ; Quantum mechanics ; Receptor ; Computer science Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Metal-Catalyzed Oxygenation Mechanisms
Authors: Luidgi Giordano | Matheus Nunes | Verônica C. Teixeira | Lucas Carvalho Veloso Rodrigues
Source: Journal of the Brazilian Chemical Society (article, 2021-01-01)
Field: Materials Science — Materials Chemistry

Green Synthesis of Upconverting NaYF4 and NaGdF4 Materials and Energy Levels Determination An alternative green route using a domestic microwave oven to synthesize NaGdF4:Yb,Tm and NaYF4:Yb,Er was successfully developed. Decreasing dopants concentration increased the β-NaREF4/α-NaREF4 ratio in NaGdF4. The scanning electron microscopy (SEM) images of NaGdF4 showed particles ranging from 500 nm to 1 μm with formation of aggregates up to 100 μm, with two different surface morphologies. The NaGdF4:Yb,Tm emission spectrum showed white-like emission due to Er3+ and Eu3+ contamination. The bandgaps of undoped NaGdF4 and NaYF4 were measured using synchrotron radiation vacuum-UV (VUV) diffuse reflectance, with values of 10.20 eV for the cubic phase and 10.80 eV for the hexagonal phase for both materials. The determination of the RE2+/3+ energy level positions in these fluorides sheds new light on the design of efficient upconversion materials. Dopant ; Materials science ; Photon upconversion ; Scanning electron microscope ; Phase (matter) ; Hexagonal phase ; Synchrotron radiation ; Hexagonal crystal system ; Nanotechnology ; Analytical Chemistry (journal) ; Luminescence ; Optoelectronics ; Doping ; Chemistry ; Optics ; Crystallography Luminescence Properties of Advanced Materials ; Inorganic Fluorides and Related Compounds
Authors: Nicolas Debons | Kenta Matsumoto | Noriyuki Hirota | Thibaud Coradin | Toshiyuki Ikoma | Carole Aimé
Source: Biomolecules (article, 2021-05-18)
Field: Materials Science — Biomaterials

Magnetic Field Alignment, a Perspective in the Engineering of Collagen-Silica Composite Biomaterials Major progress in the field of regenerative medicine is expected from the design of artificial scaffolds that mimic both the structural and functional properties of the ECM. The bionanocomposites approach is particularly well fitted to meet this challenge as it can combine ECM-based matrices and colloidal carriers of biological cues that regulate cell behavior. Here we have prepared bionanocomposites under high magnetic field from tilapia fish scale collagen and multifunctional silica nanoparticles (SiNPs). We show that scaffolding cues (collagen), multiple display of signaling peptides (SiNPs) and control over the global structuration (magnetic field) can be combined into a unique bionanocomposite for the engineering of biomaterials with improved cell performances. Tissue engineering ; Scaffold ; Regenerative medicine ; Nanotechnology ; Materials science ; Composite number ; Biomimetic materials ; Biomedical engineering ; Chemistry ; Cell ; Composite material ; Engineering Collagen: Extraction and Characterization ; Bone Tissue Engineering Materials ; Silk-based biomaterials and applications
Authors: Franziska Jach | Frank R. Wagner | Zeeshan H. Amber | Michael Rüsing | Jens Hunger | Yurii Prots | Martin Kaiser | Matej Bobnar | Anton Jesche | Lukas M. Eng | Michael Ruck | Peter Höhn
Source: Angewandte Chemie International Edition (article, 2021-05-03)
Field: Chemistry — Inorganic Chemistry

Tricyanidoferrates(−IV) and Ruthenates(−IV) with Non‐Innocent Cyanido Ligands Exceptionally electron-rich, nearly trigonal-planar tricyanidometalate anions [Fe(CN)<sub>3</sub> ]<sup>7-</sup> and [Ru(CN)<sub>3</sub> ]<sup>7-</sup> were stabilized in LiSr<sub>3</sub> [Fe(CN)<sub>3</sub> ] and AE<sub>3.5</sub> [M(CN)<sub>3</sub> ] (AE=Sr, Ba; M=Fe, Ru). They are the first examples of group 8 elements with the oxidation state of -IV. Microcrystalline powders were obtained by a solid-state route, single crystals from alkali metal flux. While LiSr<sub>3</sub> [Fe(CN)<sub>3</sub> ] crystallizes in P6<sub>3</sub> /m, the polar space group P6<sub>3</sub> with three-fold cell volume for AE<sub>3.5</sub> [M(CN)<sub>3</sub> ] is confirmed by second harmonic generation. X-ray diffraction, IR and Raman spectroscopy reveal longer C-N distances (124-128 pm) and much lower stretching frequencies (1484-1634 cm<sup>-1</sup> ) than in classical cyanidometalates. Weak C-N bonds in combination with strong M-C π-bonding is a scheme also known for carbonylmetalates. Instead of the formal notation [Fe<sup>-IV</sup> (CN<sup>-</sup> )<sub>3</sub> ]<sup>7-</sup> , quantum chemical calculations reveal non-innocent intermediate-valent CN<sup>1.67-</sup> ligands and a closed-shell d<sup>10</sup> configuration for Fe, that is, Fe<sup>2-</sup> . Raman spectroscopy ; Crystallography ; Chemistry ; Alkali metal ; Oxidation state ; Microcrystalline ; Metal ; Physics Inorganic Chemistry and Materials ; Magnetism in coordination complexes ; Organometallic Complex Synthesis and Catalysis