jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Masahiro Kamada | Antti Laitinen | Weijun Zeng | M. Will | Jayanta Sarkar | Kirsi Tappura | Heikki Seppä | Pertti Hakonen
Source: Nano Letters (article, 2021-09-07)
Field: Materials Science — Materials Chemistry

Electrical Low-Frequency 1/<i>f</i><sup>γ</sup> Noise Due to Surface Diffusion of Scatterers on an Ultra-low-Noise Graphene Platform Low-frequency 1/<i>f</i> <sup>γ</sup> noise is ubiquitous, even in high-end electronic devices. Recently, it was found that adsorbed O<sub>2</sub> molecules provide the dominant contribution to flux noise in superconducting quantum interference devices. To clarify the basic principles of such adsorbate noise, we have investigated low-frequency noise, while the mobility of surface adsorbates is varied by temperature. We measured low-frequency current noise in suspended monolayer graphene Corbino samples under the influence of adsorbed Ne atoms. Owing to the extremely small intrinsic noise of suspended graphene, we could resolve a combination of 1/<i>f</i> <sup>γ</sup> and Lorentzian noise induced by the presence of Ne. We find that the 1/<i>f</i> <sup>γ</sup> noise is caused by surface diffusion of Ne atoms and by temporary formation of few-Ne-atom clusters. Our results support the idea that clustering dynamics of defects is relevant for understanding of 1/<i>f</i> noise in metallic systems. Noise (video) ; Graphene ; Diffusion ; Infrasound ; Low frequency ; Atomic physics ; Physics ; Chemical physics ; Materials science ; Molecular physics ; Chemistry ; Optoelectronics ; Nanotechnology ; Acoustics ; Quantum mechanics Graphene research and applications ; Quantum and electron transport phenomena ; Quantum Information and Cryptography
Authors: José Eduardo Cadena-Cruz | Luis Miguel Guamán‐Ortiz | Juan Carlos Romero-Benavides | Natalia Bailón-Moscoso | Kevin E. Murillo-Sotomayor | Nadia V. Ortiz-Guamán | Jorge Heredia‐Moya
Source: BMC Chemistry (article, 2021-06-03)
Field: Chemistry — Organic Chemistry

Synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) and evaluation of their antioxidant and anticancer activities Several derivatives proved to be cytotoxic in the RKO cell line. In particular, compound 3i proved to be a very potent scavenger with an IC<sub>50</sub> of 6.2 ± 0.6 µM and exhibited an IC<sub>50</sub> of 9.9 ± 1.1 μM against RKO cell. Autophagy proteins were activated as a survival mechanism, whereas the predominant pathway of death was p53-mediated apoptosis. Chemistry ; Antioxidant ; Ascorbic acid ; Cytotoxic T cell ; DPPH ; Apoptosis ; Cell culture ; Stereochemistry ; Pyrazole ; Free radical scavenger ; In vitro ; Biochemistry Free Radicals and Antioxidants ; Synthesis and biological activity ; Multicomponent Synthesis of Heterocycles
Authors: Ryo Murata | Zhe Wang | Manabu Abe
Source: Australian Journal of Chemistry (article, 2021-11-10)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Singly Occupied Molecular Orbital-Highest Occupied Molecular Orbital (SOMO-HOMO) Conversion Singly occupied molecular orbital-highest occupied molecular orbital (SOMO-HOMO) conversion (inversion), SHC, is a phenomenon in which the SOMO is lower in energy than the doubly occupied molecular orbitals (DOMO, HOMO). A non-Aufbau electronic structure leads to unique properties such as a switch in bond dissociation energy and the generation of high-spin species on one-electron oxidation. In addition, the pronounced photostability of these species has been reported recently for application in organic light-emitting devices. In this review article, we summarise the chemistry of SOMO-HOMO converted (inverted) species reported to date. Molecular orbital ; HOMO/LUMO ; Chemistry ; Non-bonding orbital ; Molecular orbital diagram ; Dissociation (chemistry) ; Supramolecular chemistry ; Atomic orbital ; Molecular orbital theory ; Crystallography ; Computational chemistry ; Orbital overlap ; Chemical physics ; Electron ; Physical chemistry ; Crystal structure ; Molecule ; Physics ; Organic chemistry Magnetism in coordination complexes ; Porphyrin and Phthalocyanine Chemistry ; Organic and Molecular Conductors Research
Authors: Jin Zhao | Wenxiong Song | Tianjiao Xin | Zhitang Song
Source: Nature Communications (article, 2021-11-09)
Field: Materials Science — Materials Chemistry

Rules of hierarchical melt and coordinate bond to design crystallization in doped phase change materials While alloy design has practically shown an efficient strategy to mediate two seemingly conflicted performances of writing speed and data retention in phase-change memory, the detailed kinetic pathway of alloy-tuned crystallization is still unclear. Here, we propose hierarchical melt and coordinate bond strategies to solve them, where the former stabilizes a medium-range crystal-like region and the latter provides a rule to stabilize amorphous. The Er<sub>0.52</sub>Sb<sub>2</sub>Te<sub>3</sub> compound we designed achieves writing speed of 3.2 ns and ten-year data retention of 161 °C. We provide a direct atomic-level evidence that two neighbor Er atoms stabilize a medium-range crystal-like region, acting as a precursor to accelerate crystallization; meanwhile, the stabilized amorphous originates from the formation of coordinate bonds by sharing lone-pair electrons of chalcogenide atoms with the empty 5d orbitals of Er atoms. The two rules pave the way for the development of storage-class memory with comprehensive performance to achieve next technological node. Crystallization ; Crystal (programming language) ; Materials science ; Chalcogenide ; Lone pair ; Amorphous solid ; Phase (matter) ; Atomic orbital ; Chemical physics ; Doping ; Alloy ; Crystallography ; Computer science ; Electron ; Optoelectronics ; Chemistry ; Thermodynamics ; Physics ; Molecule ; Composite material Phase-change materials and chalcogenides ; Transition Metal Oxide Nanomaterials ; Advanced Memory and Neural Computing
Authors: Sagnik Banerjee | Purba Dutta | Amitkumar V. Jha | Prabhat Ranjan Tripati | Avireni Srinivasulu | Bhargav Appasani | Cristian Ravariu
Source: Progress In Electromagnetics Research M (article, 2021-12-30)
Field: Materials Science — Electronic, Optical and Magnetic Materials

A TRIPLE BAND HIGHLY SENSITIVE REFRACTIVE INDEX SENSOR USING TERAHERTZ METAMATERIAL PERFECT ABSORBER This research introduces a novel design of a metamaterial absorber having the range in terahertz, capable of sensing changes in the refractive index of the encircling medium. The layout includes adjoining rectangular patches in the form of a plus symbol along with four circular patch resonators (CPRs) on the pinnacle of a Gallium Arsenide (GaAs) substrate. The proposed design comes up with three consecutive absorption peaks, with an absorptivity of 99.0%, 99.75%, and 98.0% at three different resonant frequencies of 2.36 THz, 2.675 THz, and 2.97 THz, respectively, and a Full Width Half Maximum (FWHM) of 0.08, 0.04, and 0.05. This structure's quality factor (Q-factor) at the three resonant frequencies is 29.5, 66.8, and 59.4 together with 6.75, 17.5, and 30 as figure of merit (FoM), respectively. The proposed design offers a sensitivity of 0.54 THz/RIU, 0.7 THz/RIU, and 1.5 THz/RIU in those three absorption bands. To support the selection of design parameters, parametric assessment was done. The designed sensor can find its applications in terahertz sensing. Terahertz radiation ; Metamaterial ; Metamaterial absorber ; Refractive index ; Materials science ; Optoelectronics ; Negative index metamaterials ; Tunable metamaterials ; Optics ; Terahertz metamaterials ; Split-ring resonator ; Physics ; Far-infrared laser Metamaterials and Metasurfaces Applications ; Plasmonic and Surface Plasmon Research ; Photonic Crystals and Applications
Authors: Paavo A. Penttilä | Aleksi Zitting | Tainise V. Lourençon | Michael Altgen | Ralf Schweins | Lauri Rautkari
Source: Cellulose (article, 2021-10-18)
Field: Materials Science — Biomaterials

Water-accessibility of interfibrillar spaces in spruce wood cell walls Abstract Water interactions and accessibility of the nanoscale components of plant cell walls influence their properties and processability in relation to many applications. We investigated the water-accessibility of nanoscale pores within the fibrillar structures of unmodified Norway spruce cell walls by small-angle neutron scattering (SANS) and Fourier-transform infra-red (FTIR) spectroscopy. The different sensitivity of SANS to hydrogenated ( $$\hbox {H}_2\hbox {O}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:math> ) and deuterated water ( $$\hbox {D}_2\hbox {O}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>D</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:math> ) was utilized to follow the exchange kinetics of water among cellulose microfibrils. FTIR spectroscopy was used to study the time-dependent re-exchange of OD groups to OH in wood samples transferred from liquid $$\hbox {D}_2\hbox {O}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>D</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:math> to $$\hbox {H}_2\hbox {O}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:math> . In addition, the effects of drying on the nanoscale structure and its water-accessibility were addressed by comparing SANS results and the kinetics of water exchange between never-dried and dried/rewetted wood samples. The results of the kinetic analyses allowed to identify two processes with different timescales. The diffusion-driven exchange of water in the spaces between microfibrils, which was observed with both SANS and FTIR, takes place within minutes and rather homogeneously. The second, slower process appeared only in the OD/OH re-exchange followed by FTIR, and it still continued after several weeks of immersion in $$\hbox {H}_2\hbox {O}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:math> . SANS could not detect any significant difference between the never-dried and dried/rewetted samples, whereas FTIR revealed a small portion of OD groups that resisted the re-exchange and this portion became larger with drying. Graphic abstract Materials science ; Algorithm ; Analytical Chemistry (journal) ; Chemistry ; Computer science ; Chromatography Advanced Cellulose Research Studies ; Wood Treatment and Properties ; Cultural Heritage Materials Analysis
Authors: Nir Ganonyan | Galit Bar | Raz Gvishi | David Avnir
Source: RSC Advances (article, 2021-01-01)
Field: Chemistry — Spectroscopy

Gradual hydrophobization of silica aerogel for controlled drug release We report on the successful fine-tuning of silica aerogel hydrophobicity, through a gas-phase surface modification process. Aerogel hydrophobicity is a widely discussed matter, as it contributes to the aerogel's preservation and determines its functionality. Still, a general procedure for tuning the hydrophobicity, without affecting other aerogel properties was missing. In the developed procedure, silica aerogel was modified with trimethylchlorosilane vapor for varying durations, resulting in gradual hydrophobicity, determined by solid-state NMR and contact angle measurements. The generality of this post-synthesis treatment allows its application on a variety of aerogel materials, while having minimum effect on their porosity and transparency. We demonstrate the applicability of the gradual hydrophobization by tuning drug release rates from the silica aerogel. Two chlorhexidine salts - widely employed as antiseptic agents - were used as model drugs, one representing a soluble drug, and the other an insoluble drug; they were entrapped in silica aerogel, following hydrophobization to varying degrees. The drug release patterns showed that depending on the degree, hydrophobization can increase or decrease release kinetics, compared to the unmodified aerogel. This arises from the effect of the hydrophobic degree on pore structure, diffusional rates and wetting of the aerogel carrier. We suggest the use of the gradual hydrophobization process for other drug-aerogel systems, as well as for other aerogel applications, such as transparent insulation panels, contaminate sorbents or catalysis supports. Aerogel ; Drug ; Chemical engineering ; Chemistry ; Nanotechnology ; Materials science ; Pharmacology ; Medicine ; Engineering Aerogels and thermal insulation ; Mesoporous Materials and Catalysis ; Surface Modification and Superhydrophobicity
Authors: Masayuki Gon | Junko Wakabayashi | Masashi Nakamura | Kazuo Tanaka | Yoshiki Chujo
Source: Chemistry - An Asian Journal (article, 2021-02-03)
Field: Materials Science — Materials Chemistry

Controlling Energy Gaps of π‐Conjugated Polymers by Multi‐Fluorinated Boron‐Fused Azobenzene Acceptors for Highly Efficient Near‐Infrared Emission We demonstrate that multi-fluorinated boron-fused azobenzene (BAz) complexes can work as a strong electron acceptor in electron donor-acceptor (D-A) type π-conjugated polymers. Position-dependent substitution effects were revealed, and the energy level of the lowest unoccupied molecular orbital (LUMO) was critically decreased by fluorination. As a result, the obtained polymers showed near-infrared (NIR) emission (λ<sub>PL</sub> =758-847 nm) with high absolute photoluminescence quantum yield (Φ<sub>PL</sub> =7-23%) originating from low-lying LUMO energy levels of the BAz moieties (-3.94 to -4.25 eV). Owing to inherent solid-state emissive properties of the BAz units, deeper NIR emission (λ<sub>PL</sub> =852980 nm) was detected in film state. Clear solvent effects prove that the NIR emission is from a charge transfer state originating from a strong D-A interaction. The effects of fluorination on the frontier orbitals are well understandable and predictable by theoretical calculation with density functional theory. This study demonstrates the effectiveness of fluorination to the BAz units for producing a strong electron-accepting unit through fine-tuning of energy gaps, which can be the promising strategy for designing NIR absorptive and emissive materials. HOMO/LUMO ; Conjugated system ; Materials science ; Photoluminescence ; Polymer ; Photochemistry ; Acceptor ; Azobenzene ; Density functional theory ; Band gap ; Molecular orbital ; Quantum yield ; Electron acceptor ; Electron affinity (data page) ; Chemistry ; Optoelectronics ; Molecule ; Computational chemistry ; Organic chemistry ; Fluorescence ; Physics ; Optics Luminescence and Fluorescent Materials ; Organic Light-Emitting Diodes Research ; Organic Electronics and Photovoltaics
Authors: Pan Wang | Gen Luo | Jimin Yang | Xuefeng Cong | Zhaomin Hou | Yi Luo
Source: The Journal of Organic Chemistry (article, 2021-02-22)
Field: Chemistry — Organic Chemistry

Theoretical Studies of Rare-Earth-Catalyzed [3 + 2] Annulation of Aromatic Aldimine with Styrene: Mechanism and Origin of Diastereoselectivity The synthesis of multisubstituted 1-aminoindanes through catalyst-controlled diastereodivergent [3 + 2] annulation of aromatic imines with alkenes is of great interest and importance. An understanding of the exact reaction mechanism, especially for the origin of diastereoselectivity, is an essential aspect for further development of such reactions. In this study, density functional theory calculations have been carried out on the rare-earth-catalyzed diastereodivergent [3 + 2] annulation of benzaldimine with styrene. The results show that the reaction mainly involves generation of active species, olefin insertion, cyclization, and protonation steps. The noncovalent interactions, such as C-H···π and metal···π interactions, play an important role in stabilizing the key transition state or intermediate. Both steric and electronic factors account for the diastereoselectivity. The preferred <i>cis</i>-diastereoselectivity could be ascribed to more efficient orbital interaction, while the crowded space will induce the formation of a C-H···π interaction between the N<i><sup>t</sup></i>Bu group and benzene ring in a <i>trans</i>-diastereoselectivity manner, thus stabilizing the <i>trans</i>-selective transition state. Therefore, the stereospecific product could be obtained by fine-tuning the ligand/metal combination of the catalysts. Chemistry ; Annulation ; Steric effects ; Transition state ; Catalysis ; Protonation ; Density functional theory ; Aldimine ; Stereospecificity ; Styrene ; Stereochemistry ; Non-covalent interactions ; Computational chemistry ; Molecule ; Organic chemistry ; Copolymer Catalytic C–H Functionalization Methods ; Cyclopropane Reaction Mechanisms ; Asymmetric Hydrogenation and Catalysis
Authors: Xiaolu Zhou | Songlin Xu | Liqiang Liu | Yiping Sun | Jinxi Cheng | Xingyu Duan | Lishan Zhou | Hongmei Qu
Source: Dyes and Pigments (article, 2021-02-15)
Field: Materials Science — Materials Chemistry

5,5-Dioxoyphenothiazine-based D-A-D type AIE molecules enabling persistent room temperature phosphorescence, white light emission and dual-mode mechanochromism Phosphorescence ; Fluorescence ; Intermolecular force ; Dual mode ; Luminescence ; Photochemistry ; Molecule ; Materials science ; Chemistry ; Optoelectronics ; Optics ; Organic chemistry ; Physics Luminescence and Fluorescent Materials ; Organic Light-Emitting Diodes Research ; Nanoplatforms for cancer theranostics
Authors: Rana Al Nakib | Antoniya Toncheva | Véronique Fontaine | Jérôme Vanheuverzwijn | Jean‐Marie Raquez | F. Meyer
Source: Journal of Applied Polymer Science (article, 2021-09-20)
Field: Chemistry — Organic Chemistry

Thermoplastic polyurethanes for biomedical application: A synthetic, mechanical, antibacterial, and cytotoxic study Abstract Thermoplastic polyurethanes (TPUs) bear tunable chemistry offering the possibility to develop a rich palette of physio‐mechanical properties, making the materials suitable for various fields of application. The great variety in TPUs properties comes from the choices of the monomers and the reaction conditions. Herein, the mechanical properties of the developed TPUs are tailored, while fine‐tuning the hard and soft segment molar ratio, as well as the reaction conditions. TPUs are synthesized from 4,4′‐methylenebis(phenyl isocyanate), poly(tetrahydrofuran), and 1,4‐butanediol, and their thermal and mechanical properties are fully characterized. The sample with the most appropriate mechanical properties that are suitable for catheter fabrication, is selected for the biomedical application. Quaternary ammonium salt is synthesized, and 0.5 mol% is incorporated in the TPU to confer antibacterial properties to the material while preserving its mechanical strength. The microbiological tests reveal the antibacterial effect of the developed materials against Staphylococcus aureus and Pseudomonas aeruginosa , as well as 80% SiHa cell viability, after 72 h of exposure, as part of the performed cytotoxicity studies. Finally, TPUs catheter prototypes fabrication is also proposed, applying an extrusion or injection molding approach for the production of biomedical devices with desirable mechanical properties. Materials science ; Thermoplastic polyurethane ; Thermoplastic ; Composite material ; Polyurea ; Copolymer ; Isocyanate ; Microporous material ; Fabrication ; Chemical engineering ; Polymer ; Polyurethane ; Elastomer Antimicrobial agents and applications ; Polymer composites and self-healing ; biodegradable polymer synthesis and properties
Authors: Gianluca Viscusi | Elena Lamberti | Vittoria Vittoria | Giuliana Gorrasi
Source: Polymers for Advanced Technologies (article, 2021-06-20)
Field: Materials Science — Biomaterials

Coaxial electrospun membranes of poly(ε‐caprolactone)/poly(lactic acid) with reverse <scp>core‐shell</scp> structures loaded with curcumin as tunable drug delivery systems Abstract Nano fibrous membranes core‐shell of poly(lactic acid) (PLA) and poly(ε‐caprolactone) (PCL), encapsulating 1 wt% of curcumin, are fabricated by coaxial electrospinning technique. Morphology and physical properties, as well as the release of curcumin, are studied and compared with neat PLA and PCL individually spinned. Morphological analysis shows for all the samples the obtainment of fiber oriented in random way, without defect and with a narrow distribution of the fiber dimensions (344 nm for PCL fibers and 450 nm for PLA fibers). Mechanical performances and barrier properties are evaluated on all membranes and found to be dependent on the fibers' composition and morphology. Water contact angle for all membranes is found higher than 90° (from 103° for PLA‐Curc to 128° for PCL‐Curc), expected since the hydrophobic behavior of the micro/nano electrospun morphology. The curcumin release from the coaxial fibers, modeled with a modified Weibull equation, shows the possibility of a fine tuning of drug release (up to 15 days) for the produced materials, depending on the required application. Materials science ; Membrane ; Electrospinning ; Curcumin ; Fiber ; Caprolactone ; Chemical engineering ; Morphology (biology) ; Lactic acid ; Drug delivery ; Coaxial ; Nanofiber ; Composite material ; Polymer chemistry ; Nanotechnology ; Polymer ; Chemistry ; Copolymer Electrospun Nanofibers in Biomedical Applications ; biodegradable polymer synthesis and properties ; Nanocomposite Films for Food Packaging