jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Lixiang Yao | Yuanlong Liang | Kui Wen | Yanlin Xu | Jibin Liu | Peiguo Liu | Xianjun Huang
Source: Applied Sciences (article, 2021-05-31)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Demonstration of Tunable Shielding Effectiveness in GHz and THz Bands for Flexible Graphene/Ion Gel/Graphene Film To satisfy the demands of wireless communication systems for tunable shielding materials, in this work, a graphene/ion gel/graphene sandwich structure is proposed, based on graphene and a solid ionic material ion gel. After modelling, preparing and testing, it was found that the structure could achieve more than 10 dB shielding effectiveness tuning in GHz and THz bands. Meanwhile, the adjusting speed of the structure was also studied, displaying effective dynamic tuning in the second order. Furthermore, the fabricated samples have the advantages of a low profile, easily conformable, and convenient processing, which are of great potential in emerging electronic devices. Graphene ; Materials science ; Conformable matrix ; Electromagnetic shielding ; Terahertz radiation ; Optoelectronics ; Nanotechnology ; Ion ; Shielding effect ; Composite material ; Chemistry Electromagnetic wave absorption materials ; Advanced Antenna and Metasurface Technologies ; Metamaterials and Metasurfaces Applications
Authors: P. Badica | Dan Batalu | Mariana Carmen Chifiriuc | M. Burdusel | Mihai Alexandru Grigoroscuta | G. Aldica | Iuliana Pasuk | Andrei Kuncser | Monica Enculescu | Marcela Popa | Luminița Măruțescu | Irina Gheorghe | O. Thamer | Coralia Bleoţu | Grațiela Grădișteanu Pîrcălăbioru | Lorenza Operti | Valentina Bonino | Angelo Agostino | Marco Truccato
Source: Journal of Materials Research and Technology (article, 2021-04-23)
Field: Materials Science — Materials Chemistry

MgB2 powders and bioevaluation of their interaction with planktonic microbes, biofilms, and tumor cells Commercial nanopowders of MgB2 were characterized from the viewpoint of granulometric distribution, structure, microstructure, and pH behavior in water. The powders are very different: a higher amount of the MgB2 phase with a lower tendency for agglomeration determines a higher rate of pH-increase. A higher rate of pH-increase usually produces a stronger antimicrobial activity against Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Candida parapsilosis reference strains. The variation of the pH-increase rate suggests the possibility of temporo-spatial control of MgB2 bioactivity, although the contribution of other factors should not be neglected. Remarkably, the efficiency of the MgB2 powders is higher against biofilms than on microbes in the planktonic state. Further, our experiments confirm the antimicrobial efficiency of MgB2 in the in vitro tests against 29 methicillin resistant clinical S. aureus isolates and 33 vancomycin resistant E. faecium/faecalis strains, but in this case the biofilms are more resistant than planktonic cells. The MgB2 treatment of infected mice led to a significant decrease of E. coli colonization in liver, spleen and peritoneal liquid and it also caused changes in the intestinal microbiota. The activity of powders on HeLa and HT-29 tumor cell lines was assessed by inverted microscopy, flow cytometry, and evaluation of the cellular cycle. MgB2 inhibits tumor cell growth influencing DNA synthesis (S-phase). The obtained results indicate that the tested powders could provide promising solutions for the development of large-spectrum multifunctional antimicrobial and anti-biofilm agents, and/or for anti-cancer therapies. Biofilm ; Enterococcus faecium ; Microbiology ; Antimicrobial ; Enterococcus faecalis ; Candida albicans ; HeLa ; Staphylococcus aureus ; Escherichia coli ; Pseudomonas aeruginosa ; Biology ; Materials science ; In vitro ; Bacteria ; Antibiotics ; Biochemistry Nanoparticles: synthesis and applications ; Inhalation and Respiratory Drug Delivery ; Magnesium Oxide Properties and Applications
Authors: Neil J. Stewart | Tatsuyuki Sato | Norihiko Takeda | Hiroshi Hirata | Shingo Matsumoto
Source: Antioxidants and Redox Signaling (review, 2021-07-05)
Field: Chemistry — Spectroscopy

Hyperpolarized <sup>13</sup> C Magnetic Resonance Imaging as a Tool for Imaging Tissue Redox State, Oxidative Stress, Inflammation, and Cellular Metabolism <b><i>Significance:</i></b> Magnetic resonance imaging (MRI) with hyperpolarized (HP) <sup>13</sup>C-labeled redox-sensitive metabolic tracers can provide noninvasive functional imaging biomarkers, reflecting tissue redox state, oxidative stress, and inflammation, among others. The capability to use endogenous metabolites as <sup>13</sup>C-enriched imaging tracers without structural modification makes HP <sup>13</sup>C MRI a promising tool to evaluate redox state in patients with various diseases. <b><i>Recent Advances:</i></b> Recent studies have demonstrated the feasibility of <i>in vivo</i> metabolic imaging of <sup>13</sup>C-labeled tracers polarized by parahydrogen-induced polarization techniques, which offer a cost-effective alternative to the more widely used dissolution dynamic nuclear polarization-based hyperpolarizers. <b><i>Critical Issues:</i></b> Although the fluxes of many metabolic pathways reflect the change in tissue redox state, they are not functionally specific. In the present review, we summarize recent challenges in the development of specific <sup>13</sup>C metabolic tracers for biomarkers of redox state, including that for detecting reactive oxygen species. <b><i>Future Directions:</i></b> Applications of HP <sup>13</sup>C metabolic MRI to evaluate redox state have only just begun to be investigated. The possibility to gain a comprehensive understanding of the correlations between tissue redox potential and metabolism under different pathological conditions by using HP <sup>13</sup>C MRI is promoting its interest in the clinical arena, along with its noninvasive biomarkers to evaluate the extent of disease and treatment response. Oxidative stress ; Redox ; Magnetic resonance imaging ; Chemistry ; Biochemistry ; Medicine Advanced NMR Techniques and Applications ; Electron Spin Resonance Studies ; Advanced MRI Techniques and Applications
Authors: Jonathan Bietsch | Mary C. Olson | Guijun Wang
Source: Gels (article, 2021-09-07)
Field: Materials Science — Biomaterials

Fine-Tuning of Molecular Structures to Generate Carbohydrate Based Super Gelators and Their Applications for Drug Delivery and Dye Absorption Carbohydrate-based low molecular weight gelators (LMWGs) exhibit many desirable properties making them useful in various fields including applications as drug delivery carriers. In order to further understand the structural connection to gelation properties, especially the influence of halide substitutions, we have designed and synthesized a series of <i>para</i>-chlorobenzylidene acetal protected D-glucosamine amide derivatives. Fifteen different amides were synthesized, and their self-assembling properties were assessed in multiple organic solvents, as well as mixtures of organic solvents with water. All derivatives were found to be gelators for at least one solvent and majority formed gels in multiple solvents at concentrations lower than 2 wt%. A few derivatives rendered remarkably stable gels in aqueous solutions at concentrations below 0.1 wt%. The benzamide <b>13</b> formed gels in water and in EtOH/H<sub>2</sub>O (<i>v</i>/<i>v</i> 1:2) at 0.36 mg/mL. The gels were characterized using optical microscopy and atomic force microscopy, and the self-assembly mechanism was probed using variable temperature <sup>1</sup>H-NMR spectroscopy. Gel extrusion studies using H<sub>2</sub>O/DMSO gels successfully printed lines of gels on glass slides, which retained viscoelasticity based on rheology. Gels formed by the benzamide <b>13</b> were used for encapsulation and the controlled release of chloramphenicol and naproxen, as well as for dye removal for toluidine blue aqueous solutions. Aqueous solution ; Chemistry ; Solvent ; Benzamide ; Absorption spectroscopy ; Amide ; Chemical engineering ; Organic chemistry ; Polymer chemistry Supramolecular Self-Assembly in Materials ; RNA Interference and Gene Delivery ; Polydiacetylene-based materials and applications
Authors: Yong Li | Jia Xu | Liu‐Jun He | Yafei Luo | Jiang Ping Meng | Dianyong Tang | Hongyu Li | Zhong‐Zhu Chen | Zhigang Xu
Source: The Journal of Organic Chemistry (article, 2021-12-17)
Field: Chemistry — Organic Chemistry

Dieckmann Condensation of Ugi <i>N</i>-Acylamino Amide Product: Facile Access to Functionalized 2,2-Disubstituted Indolin-3-ones Structurally unique 2,2-disubstituted indolin-3-ones with a quaternary carbon center have been constructed through a novel C-C bond formation at the C3 position of Ugi <i>N</i>-acylamino amide adducts employing an organic base-mediated Dieckmann condensation. This facile, flexible protocol can be fine-tuned to construct drug-like pyrazino[1,2-<i>a</i>]indole fragments with the same quaternary carbon center only through the variation of the acid part in Ugi input. This novel and expeditious methodology has a broad scope and can rapidly generate the drug-like indolin-3-one core. Chemistry ; Amide ; Adduct ; Combinatorial chemistry ; Quaternary carbon ; Indole test ; Condensation ; Condensation reaction ; Stereochemistry ; Organic chemistry ; Catalysis ; Enantioselective synthesis Multicomponent Synthesis of Heterocycles ; Synthesis of Organic Compounds ; Chemical Synthesis and Analysis
Authors: David Sonnleitner | Natascha Schaefer | Annalena Wieland | Lena Fischer | Patrick Pasberg | Ingo Thievessen | Gregor Lang
Source: Applied Materials Today (article, 2021-06-28)
Field: Materials Science — Biomaterials

PCL micro-dumbbells – A new class of polymeric particles reveals morphological biofunctionality Biopolymeric particles can be fibrous or spherical, highly determining their areas of medical applications such as biomimetic fibers for tissue engineering or injectable capsules. In this work, we present a completely novel morphology, combining structural features of fibers and spheres in dumbbell-shaped Poly-ε-Caprolactone (PCL) micro-particles. Strikingly, such complex structures could be achieved by simply balancing out the parameters of a standard electrospinning setup together with fine-tuned spinning dope compositions. In-situ entropy-elastic snapping of deposited fibers could be triggered by combining PCL with different molecular weights, allowing for control over the aspect ratio of generated dumbbells in an accurate manner. With a single electrospinning nozzle, high production rates in the range of 80.000 dumbbells per second were achieved. To assess morphologically induced biofunctionality, dumbbell suspending and surface modification with collagen was performed and in vitro-testing with U87 reporter cells demonstrated significantly enhanced integrin-based cell adhesion on PCL-dumbbells as compared to continuous PCL-fibers. The results clearly unravel the remarkable potential of such structures in the field of tissue engineering. Revealing this new class of polymeric particles will also open the door to various new approaches including injectables, biofabrication and cosmetics, moreover, defining a novel type of filler material. Biofabrication ; Materials science ; Electrospinning ; Spinning ; Dumbbell ; Tissue engineering ; Nanotechnology ; Polymer ; Composite material ; Biomedical engineering Electrospun Nanofibers in Biomedical Applications ; Additive Manufacturing and 3D Printing Technologies ; 3D Printing in Biomedical Research
Authors: Amrita Sikder | Yujie Xie | M. Thomas | Matthew J. Derry | Rachel K. O’Reilly
Source: Nanoscale (article, 2021-01-01)
Field: Materials Science — Biomaterials

Precise control over supramolecular nanostructures<i>via</i>manipulation of H-bonding in π-amphiphiles Self-assembled supramolecular architectures are ubiquitous in nature. A synchronized combination of dynamic noncovalent interactions is the major driving force in forming unique structures with high-precision control over the self-assembly of supramolecular materials. Herein, we have achieved programmable nanostructures by introducing single/multiple H-bonding units in a supramolecular building block. A diverse range of nanostructures can be generated in aqueous medium by subtly tuning the structure of π-amphiphiles. 1D-cylindrical micelles, 2D-nanoribbons and hollow nanotubes are produced by systematically varying the number of H-bonding units (0-2) in structurally near identical π-amphiphiles. Spectroscopic measurements revealed the decisive role of H-bonding units for different modes of molecular packing. We have demonstrated that a competitive self-assembled state (a kinetically controlled aggregation state and a thermodynamically controlled aggregation state) can be generated by fine tuning the number of noncovalent forces present in the supramolecular building blocks. The luminescence properties of conjugated dithiomaleimide (DTM) provided insight into the relative hydrophobicity of the core in these nanostructures. In addition, fluorescence turn-off in the presence of thiophenol enabled us to probe the accessibility of the hydrophobic core in these assembled systems toward guest molecules. Therefore the DTM group provides an efficient tool to determine the relative hydrophobicity and accessibility of the core of various nanostructures which is very rarely studied in supramolecular assemblies. Supramolecular chemistry ; Amphiphile ; Nanostructure ; Materials science ; Nanotechnology ; Supramolecular assembly ; Crystallography ; Chemistry ; Copolymer ; Crystal structure ; Polymer ; Composite material Supramolecular Self-Assembly in Materials ; Porphyrin and Phthalocyanine Chemistry ; Polydiacetylene-based materials and applications
Authors: Yuan Liu | Yan Zhang | Peixin Zhang | Yong Peng | Xing Liu | Jingwen Chen | Shixia Chen | Zheling Zeng | Jun Wang | Shuguang Deng
Source: Chemical Engineering and Processing - Process Intensification (article, 2021-12-29)
Field: Chemistry — Inorganic Chemistry

Two novel 4,6-connected anion-pillared metal-organic frameworks for simultaneous separation of C3 and C4 olefins Propane ; Adsorption ; Olefin fiber ; Metal-organic framework ; Ion ; Materials science ; Molecule ; Chemical engineering ; Chemistry ; Inorganic chemistry ; Organic chemistry ; Catalysis Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Machine Learning in Materials Science
Authors: Jun Dong | Yan Wang | Qianying Wang | Yi Cao | Qingyan Han | Wei Gao | Yongkai Wang | Jianxia Qi | Mengtao Sun
Source: Nanotechnology (article, 2021-12-15)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Nanoscale engineering of ring-mounted nanostructure around AAO nanopores for highly sensitive and reliable SERS substrates Surface-enhanced Raman scattering (SERS) is recognized as one of the most favored techniques for enhancing Raman signals. The morphology of the SERS substrate profoundly affects molecular Raman spectra. This study aimed to construct a ring-mounted nanostructured substrate via liquid-liquid two-phase self-assembly incorporated with anodic aluminum oxide (AAO) membrane transfer techniques. High-density nanoparticles (NPs) assembled on AAO membranes were ascribed to reduce the diameters of the nanopores, with Au-Ag alloy NPs to regulate the dielectric constant so as to reveal the local surface plasmon resonance tunability. SERS engineered in this way allowed for the fabrication of a ring-mounted nanostructured substrate where the distribution density of NPs and dielectric constant could be independently fine-tuned. High SERS activity of the substrate was revealed by detecting the enhanced factor of crystal violet and rhodamine 6G molecules, which was up to 1.56 × 10<sup>6</sup>. Moreover, SERS of thiram target molecules confirmed the supersensitivity and repeatability of the substrate as a practical application. The results of this study manifested a low-cost but high-efficiency ring-mounted nanostructured SERS substrate that might be suitable in many fields, including biosensing, medical research, environmental monitoring, and optoelectronics. Materials science ; Rhodamine 6G ; Nanotechnology ; Raman scattering ; Nanopore ; Substrate (aquarium) ; Coffee ring effect ; Raman spectroscopy ; Nanostructure ; Dielectric ; Plasmon ; Surface plasmon resonance ; Nanoparticle ; Optoelectronics ; Molecule ; Optics Gold and Silver Nanoparticles Synthesis and Applications ; Polymer Surface Interaction Studies ; Advanced biosensing and bioanalysis techniques
Authors: S. Aria Hosseini | Giuseppe Romano | P. Alex Greaney
Source: ACS Applied Energy Materials (article, 2021-02-11)
Field: Materials Science — Materials Chemistry

Mitigating the Effect of Nanoscale Porosity on Thermoelectric Power Factor of Si The addition of porosity to thermoelectric (TE) materials can significantly increase the figure of merit, ZT, by reducing the thermal conductivity. Unfortunately, porosity is also detrimental to the TE power factor (PF) in the numerator of the figure of merit, ZT. In this manuscript, we derive strategies to recoup electrical performance in nanoporous Si by fine tuning the carrier concentration and through judicious design of the pore size and shape so as to provide energy-selective electron filtering. In this study, we considered phosphorus-doped silicon containing discrete pores that are either spheres, cylinders, cubes, or triangular prisms. The effects from these pores are compared with those from extended pores with circular, square, and triangular cross-sectional shape and infinite length perpendicular to the electrical current. A semiclassical Boltzmann transport equation is used to model Si TE PF. This model reveals three key results: the largest enhancement in Seebeck coefficient occurs with cubic pores. The fractional improvement is about 15% at low carrier concentration (<1020 1/cm3) and up to 60% at high carrier population with characteristic length around ∼1 nm. To obtain the best energy filtering effect at room temperature, nanoporous Si needs to be doped to higher carrier concentration than is optimal for bulk Si. Finally, in n-type Si TEs, the electron filtering effect that can be generated with nanoscale porosity is significantly lower than the ideal filtering effect; nevertheless, the enhancement in the Seebeck coefficient that can be obtained is large enough to offset the reduction in electrical conductivity caused by porosity. Materials science ; Porosity ; Nanoscopic scale ; Thermoelectric effect ; Power factor ; Engineering physics ; Nanotechnology ; Power (physics) ; Composite material ; Engineering ; Physics ; Thermodynamics Advanced Thermoelectric Materials and Devices ; Thermal properties of materials ; Semiconductor materials and interfaces
Authors: Eva Schiebel | Maria Voccia | Laura Falivene | Lucia Caporaso | Stefan Mecking
Source: ACS Catalysis (article, 2021-04-19)
Field: Chemistry — Organic Chemistry

The Impact of Charge in a Ni(II) Polymerization Catalyst A direct comparison between neutral active sites and their corresponding cationic analogues is enabled by protonation of neutral bis(imino)phenoxy complexes, active for ethylene polymerization. The additional imine motif compared to parent salicylaldiminato catalysts does not influence the microstructure of the products in ethylene polymerization, but allows for the incorporation of a proton right next to the active center in an N···H+···O bridge yielding cationic complexes. These show an increased Ni–O bond length and a drastically reduced electron density on the Ni atom. In pressure reactor experiments, two different catalysts that produce linear HDPE or undergo extensive chain walking, respectively, in their neutral version, both produce short chain oligomers when the catalyst is charged cationically. A mechanistic analysis by DFT methods reveals an increased propensity for β-hydride elimination compared to ethylene insertion chain growth for the cationic complexes. This results from a higher relative stability of β-agostic species vs olefin-coordinated species. Cationic polymerization ; Ethylene ; Catalysis ; Polymerization ; Protonation ; Chemistry ; Polymer chemistry ; Photochemistry ; Chain transfer ; Migratory insertion ; Polyethylene ; Organic chemistry ; Radical polymerization ; Polymer ; Ion Organometallic Complex Synthesis and Catalysis ; Carbon dioxide utilization in catalysis ; CO2 Reduction Techniques and Catalysts
Authors: Philip Schmode | Adrian Hochgesang | Mahima Goel | Florian Meichsner | John Mohanraj | Martina Fried | Mukundan Thelakkat
Source: Macromolecular Chemistry and Physics (article, 2021-06-26)
Field: Materials Science — Polymers and Plastics

A Solution‐Processable Pristine PEDOT Exhibiting Excellent Conductivity, Charge Carrier Mobility, and Thermal Stability in the Doped State Abstract PEDOT:PSS [poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate] is a widely used insoluble conducting polymer, which is therefore processed from dispersions. In this work, PEDOT homopolymers (PEDOT‐C 6 C 8 1 and 2) highly soluble in common solvents like toluene, tetrahydrofuran, and chloroform are synthesized with a high control of molecular weight and low dispersity using Kumada catalyst transfer polymerization of a newly synthesized EDOT monomer carrying a branched alkyl substituent. Pristine PEDOT‐C 6 C 8 allows the use in accumulation mode transistors with a high charge carrier mobility of 5 × 10 − 4 cm 2 V −1 s −1 . Moreover, these polymers can be doped in a controlled fashion, reaching conductivities of 10 −3 S cm −1 at 10 mol% of a dopant, Spiro‐MeOTAD(TFSI) 2 . The doped state is remarkably stable, retaining 80% of the initial value after annealing under nitrogen at 100 °C and being exposed to ambient atmosphere for up to 12 h. During doping, the hole injection barrier decreases and reaches an impressively low value of 130 meV at only 2.5 mol% dopant loading without loss in carrier mobility; as monitored using ultraviolet photoelectron‐ and impedance spectroscopy. This new design concept leading to highly soluble polymers with well‐controlled molecular weights provides solution‐processable PEDOT dopable in a well‐controlled fashion. PEDOT:PSS ; Materials science ; Dopant ; Polymer chemistry ; Polystyrene sulfonate ; Conductive polymer ; Chemical engineering ; Polymerization ; Polymer ; Doping ; Composite material Conducting polymers and applications ; Advanced Sensor and Energy Harvesting Materials ; Supercapacitor Materials and Fabrication
Authors: Yuna Jung | Dokyoung Kim
Source: Biomedical Engineering Letters (review, 2021-06-15)
Field: Materials Science — Materials Chemistry

Recent advances in hybrid system of porous silicon nanoparticles and biocompatible polymers for biomedical applications Biocompatible material ; Nanotechnology ; Materials science ; Nanoparticle ; Polymer ; Hybrid material ; Porous silicon ; Drug delivery ; Porosity ; Biomedical engineering ; Engineering Silicon Nanostructures and Photoluminescence ; Nanowire Synthesis and Applications ; Laser-Ablation Synthesis of Nanoparticles