jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Md Shafayatul Islam | Koushik Roy Chowdhury | S. Manjura Hoque | Ahmed Sharif
Source: ChemRxiv (preprint, 2023-12-07)
Field: Materials Science — Materials Chemistry

Cationic and Oxygen Defects Modulation forTailoring Bandgap and Room TemperatureFerromagnetism of CuO via Multiple d-BlockCations The potential of oxide-based dilute magnetic semiconductors (DMSs) for use in spintronics and magneto-optic devices has garnered a lot of attention over the years. However, the optical and magnetic behavior of these DMSs is challenging to navigate due to the complicated interactions of intrinsic defects. In these contexts, the current research takes a comprehensive look at the pristine and simultaneously multiple d-block cations (Cr, Fe, Ni, Co, and Zn)-doped CuO nanocrystals (NCs) to explain the defect interactions inside the lattice. Structural analysis revealed a highly crystalline monoclinic crystal structure in the C2/c space group. The phase stability of CuO NCs was found to be decreasing with increasing dosages of dopants, ultimately forming a secondary phase of Cu metal. Diffused reflectance spectroscopy (DRS) spectra showed a narrowing of the optical band gap, attributing it to the presence of impurity states between the conduction band minimum (CBM) and valence band maximum (VBM) as a result of doping. These impurity states can inhibit carrier recombination. Both pristine and doped CuO NCs showed ferromagnetism at ambient temperature with a paramagnetic tail at higher fields. This paramagnetic tail, explained based on the thermo-magnetization curves, corresponds to the easy flip of magnetic cations below room temperature. All the ferromagnetic feathers of CuO NCs may be traced back to the exchange interaction between the spins of magnetic ions, mediated by carrier-trapped vacancy centers. Interestingly, doped oxides showed improved ferromagnetism when used at moderate concentrations, which is related to the creation of a larger number of bound magnetic polarons (BMPs). Although higher dosages of dopants lower the concentration of BMPs by delocalizing the carriers from the defect centers. Ferromagnetism ; Materials science ; Paramagnetism ; Condensed matter physics ; Band gap ; Spintronics ; Magnetic semiconductor ; Doping ; Dopant ; Curie temperature ; Fermi level ; Optoelectronics ; Electron Copper-based nanomaterials and applications ; ZnO doping and properties ; Electronic and Structural Properties of Oxides
Authors: Uroš Todorović | R. Martín Romero | Lucile Anthore‐Dalion
Source: ChemRxiv (preprint, 2023-06-16)
Field: Chemistry — Organic Chemistry

Activation of N–O σ Bonds with Transition Metals: A Versatile Platform for Organic Synthesis and C–N Bonds Formation N–O σ bonds containing compounds are versatile substrates for organic synthesis under transition metal catalysis. Their ability to react through both polar (oxidative addition, formation of metallanitrene, nucleophilic substitution) and radical pathways (single electron transfer, homolytic bond scission) have triggered the development of various synthetic methodologies, particularly toward synthesizing nitrogen-containing compounds. In this review, we discuss the different modes of activation of N–O bonds in the presence of transition metal catalysts, emphasizing the experimental and computational mechanistic proofs in the literature to help to design new synthetic pathways toward the synthesis of C–N bonds. Homolysis ; Transition metal ; Organic synthesis ; Catalysis ; Chemistry ; Bond cleavage ; Nucleophile ; Combinatorial chemistry ; Reductive elimination ; Photochemistry ; Organic chemistry ; Radical Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis ; Chemical Synthesis and Reactions
Authors: Sida Wang | Phil Liebing | Martin Feneberg | Farid M. Sroor | Felix Engelhardt | Liane Hilfert | Sabine Busse | Elias Kluth | R. Goldhahn | Frank T. Edelmann
Source: European Journal of Inorganic Chemistry (article, 2023-03-07)
Field: Chemistry — Organic Chemistry

Synthesis and Structural Characterization of Divalent Transition Metal Alkynylamidinate Complexes Abstract A series of new alkynylamidinate complexes of selected first and second row transition metals has been synthesized and fully characterized. Treatment of MCl 2 precursors (M=Mn, Fe, Co) with 2 equiv. of the lithium alkynylamidinates Li[ c ‐C 3 H 5 −C≡C−C(NR′) 2 ] ⋅ THF (R′= i Pr (2), Cy (cyclohexyl) ( 2 )) afforded a series of binuclear complexes of the type M 2 [ c ‐C 3 H 5 −C≡C−C(NR) 2 ‐κ N :κ N′ ] 2 [ c ‐C 3 H 5 −C≡C−C(NR) 2 ‐κ 2 N , N′ ] 2 ( 3 : M=Mn, R=Cy; 4 a : M=Fe, R= i Pr; 4 b : M=Fe, R=Cy; 5 : M=Co, R= i Pr) with no significant metal‐metal bonding. In marked contrast, a similar reaction of CrCl 2 with 2 equiv. of 1 afforded the homoleptic dinuclear chromium(II) complex Cr 2 [ c ‐C 3 H 5 −C≡C−C(N i Pr) 2 ‐κ N :κ N′ ] 4 ( 6 ) which supposedly comprises a Cr−Cr quadruple bond. Complex 6 could also be prepared in a more rational way and in better yield (61 %) by using dichromium(II) tetraacetate, Cr 2 (OAc) 4 , as starting material. Related reactions employing dimolybdenum(II) tetraacetate, Mo 2 (OAc) 4 , and 2 or 3 equiv. of 1 afforded the mixed‐ligand paddle wheel‐type complexes trans ‐Mo 2 (OAc‐κ O :κ O′ ) 2 ([ c ‐C 3 H 5 −C≡C−C(N i Pr) 2 ‐κ N :κ N′ ] 2 ( 7 ) and Mo 2 (OAc‐κ O :κ O′ )([ c ‐C 3 H 5 −C≡C−C(N i Pr) 2 ‐κ N :κ N′ ] 3 ( 8 ). All title compounds were structurally characterized through single‐crystal X‐ray diffraction and spectroscopic techniques (NMR, IR, Raman). Chemistry ; Homoleptic ; Transition metal ; Ligand (biochemistry) ; Chromium ; Metal ; Stereochemistry ; Yield (engineering) ; Medicinal chemistry ; Divalent ; Lithium (medication) ; Crystallography ; Catalysis ; Organic chemistry Organometallic Complex Synthesis and Catalysis ; Asymmetric Hydrogenation and Catalysis ; Ferrocene Chemistry and Applications
Authors: Isabelle Martinier | Florian Fage | Alshaba Kakar | Alessia Castagnino | Emeline Saindoy | Joni Frederick | Ilaria Onorati | Valérie Besnard | Abdul I. Barakat | Nicolas Dard | Emmanuel Martinod | Carole Planès | Léa Trichet | Francisco M. Fernandes
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2023-09-01)
Field: Materials Science — Biomaterials

Tunable biomimetic materials elaborated by ice templating and self-assembly of collagen for tubular tissue engineering Synthetic tubular grafts currently used in clinical context fail frequently, and the expectations that biomimetic materials could tackle these limitations are high. However, developing tubular materials presenting structural, compositional and functional properties close to those of native tissues remains an unmet challenge. Here we describe a combination of ice templating and topotactic fibrillogenesis of type I collagen, the main component of tissues’ extracellular matrix, yielding highly concentrated yet porous tubular collagen materials with controlled hierarchical architecture at multiple length scales, the hallmark of native tissues’ organization. By modulating the thermal conductivity of the cylindrical molds, we tune the macroscopic porosity defined by ice. Coupling the aforementioned porosity patterns with two different fibrillogenesis routes results in a new family of materials whose textural features and the supramolecular arrangement of type I collagen are achieved. The resulting materials present hierarchical elastic properties and are successfully colonized by human endothelial cells and alveolar epithelial cells on the luminal side, and by human mesenchymal stem cells on the external side. The results reported here demonstrate the relevance of the proposed straightforward protocol, likely to be adapted for larger graft sizes, to address ever-growing clinical needs such as peripheral arterial disease or tracheal and bronchial reconstructions. Fibrillogenesis ; Materials science ; Extracellular matrix ; Tissue engineering ; Porosity ; Nanotechnology ; Nanotopography ; Bridging (networking) ; Biomedical engineering ; Fibril ; Biophysics ; Chemistry ; Composite material ; Computer science ; Biology ; Engineering ; Biochemistry Electrospun Nanofibers in Biomedical Applications ; Bone Tissue Engineering Materials ; Surface Modification and Superhydrophobicity
Authors: Javier Benito | Unai Urrutia | Nikos Ch. Karayiannis | Manuel Laso
Source: Preprints.org (preprint, 2023-08-14)
Field: Materials Science — Materials Chemistry

Enumeration of Self-Avoiding Random Walks on Lattices as Model Chains in Polymer Crystals Recent simulation studies have revealed a wealth of distinct crystal polymorphs encountered in the self-organization of polymer systems driven by entropy or free energy. The present analysis, based on the concept of self-avoiding random walks on crystal lattices, is useful to calculate upper bounds for the entropy difference of the crystals that are formed during polymer crystallization and thus provide predictions on polymorph thermodynamic stability. Here, we compare two pairs of crystals sharing the same coordination number, ncoord: hexagonal close packed (HCP) and face centered cubic (FCC), both having ncoord = 12 and the same packing density, and the less dense hexagonal (HEX) and body centered cubic (BCC) lattices, with ncoord = 8. In both cases, once a critical step length is reached, one of the crystals shows a higher number of SAWs compatible with the crystal. We explain the observed trends in terms of the bending and torsion angles corresponding to the different chain geometry as imposed by the geometric constraints of the crystal lattice. Crystallization ; Lattice (music) ; Hexagonal crystal system ; Polymer ; Crystallography ; Hexagonal lattice ; Crystal (programming language) ; Enumeration ; Random walk ; Crystal structure ; Materials science ; Cubic crystal system ; Entropy (arrow of time) ; Condensed matter physics ; Combinatorics ; Physics ; Mathematics ; Thermodynamics ; Chemistry ; Computer science Machine Learning in Materials Science ; Polymer crystallization and properties ; Protein Structure and Dynamics
Authors: Sara Realista | Ana Reis | V. Corregidor | L.C. Alves | S. Magalhães | Telmo Nunes | Ana M. Ferraria | A.M. Botelho do Rego | Paulo N. Martinho
Source: ChemRxiv (preprint, 2023-10-13)
Field: Materials Science — Polymers and Plastics

Electrosynthesis of iron-based metal-organic materials with bis(salicylic acid) derivatives Continuous advancements in understanding and controlling surface functionalisation and properties empower materials scientists to design materials with tailored characteristics, improved performance, and enhanced functionality, thereby expanding scientific knowledge and technological progress. This research paper presents the synthesis of two new metal-organic material-based films using the cathodic electrodeposition method. This method offers the advantage of using non-metal electrode substrates and various metal ions, a unique aspect not yet fully explored. The study investigates the effects of linker length using 2,5-dihydroxyterephthalic acid (DOBDC) and 3,3'-dihydroxybiphenyl-4,4'-dicarboxylic acid (BPP) as organic linkers and iron(III) as the metal node for the structures. The films' electrochemical behaviour, characterisation through techniques like infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-Ray powder diffraction and grazing-Incidence small-angle X-ray scattering and particle-induced X-ray emission, as well as results from cyclic voltammetry studies, are discussed. The films were found to be nearly amorphous with specific grain sizes, revealing heterogeneity in composition and thickness. The unique synthesis method and comprehensive characterisation offer insights into the potential of electrosynthesis for designing functional materials and encourage further exploration of various synthesis conditions and metal ions. Electrosynthesis ; Materials science ; Cyclic voltammetry ; X-ray photoelectron spectroscopy ; Metal-organic framework ; Amorphous solid ; Nanotechnology ; Chemical engineering ; Metal ; Electrochemistry ; Electrode ; Metallurgy ; Chemistry ; Organic chemistry ; Physical chemistry Conducting polymers and applications ; Electrodeposition and Electroless Coatings ; Electrochemical Analysis and Applications
Authors: Florian M. Arnold | Alireza Ghasemifard | Agnieszka Kuc | Thomas Heine
Source: ChemRxiv (preprint, 2023-03-22)
Field: Materials Science — Materials Chemistry

Implementing electronic signatures of graphene and hexagonal boron nitride in twisted bilayer molybdenum disulfide Angeli and MacDonald reported a superlattice-imposed Dirac band in twisted bilayer molybdenum disulphide (tBL MoS2) for small twist angles towards the R_h^M (parallel) stacking. Using a hierarchical set of theoretical methods, we show that the superlattices differ for twist angles with respect to metastable R_h^M (0°) and lowest-energy H_h^h (60°) configurations. When approaching R_h^M stacking, identical domains with opposite spatial orientation emerge. They form a honeycomb superlattice, yielding Dirac bands and a lateral spin texture distribution with opposite-spin-occupied K and K’ valleys. Small twist angles towards the H_h^h configuration (60°) generate H_h^h and H_h^X stacking domains of different relative energies and, hence, different spatial extensions. This imposes a symmetry break in the moiré cell, which opens a gap between the two top-valence bands, which become flat already for relatively small moiré cells. The superlattices impose electronic superstructures resembling graphene and hexagonal boron nitride into trivial semiconductor MoS2. Superlattice ; Stacking ; Graphene ; Condensed matter physics ; Materials science ; Bilayer graphene ; Twist ; Crystallography ; Molybdenum disulfide ; Nanotechnology ; Chemistry ; Physics ; Geometry 2D Materials and Applications ; Graphene research and applications ; Topological Materials and Phenomena
Authors: Johan G. Olsen | Andreas Prestel | Noah Kassem | Sebastian S. Broendum | Md. Shamim Hossain | Signe Simonsen | Martin Grysbæk | Josefine Mortensen | Louise Lund Rytkjær | Gitte W. Haxholm | Riccardo Marabini | Antony M. Carr | Ramón Crehuet | Olaf Nielsen | Birthe B. Kragelund
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2023-05-12)
Field: Materials Science — Materials Chemistry

Checkpoint activation by Spd1: a competition-based system relying on tandem disordered PCNA binding motifs Abstract DNA regulation, replication and repair are processes fundamental to all known organisms and the sliding clamp proliferating cell nuclear antigen (PCNA) is central to all these processes. S-phase delaying protein 1 (Spd1) from S. pombe , an intrinsically disordered protein that causes checkpoint activation by inhibiting the enzyme ribonucleotide reductase, has one of the most divergent PCNA binding motifs known. Using NMR spectroscopy, in vivo assays, X-ray crystallography, calorimetry, and Monte Carlo simulations, an additional PCNA binding motif in Spd1, a PIP-box, is revealed. The two tandemly positioned, low affinity sites exchange rapidly on PCNA exploiting the same binding sites. Increasing or decreasing the binding affinity between Spd1 and PCNA through mutations of either motif compromised the ability of Spd1 to cause checkpoint activation in yeast. These results pinpoint a role for PCNA in Spd1-mediated checkpoint activation and suggest that its tandemly positioned short linear motifs create a neatly balanced competition-based system, involving PCNA, Spd1 and the small ribonucleotide reductase subunit, Suc22 R2 . Similar mechanisms may be relevant in other PCNA binding ligands where divergent binding motifs so far have gone under the PIP-box radar. Proliferating cell nuclear antigen ; Biology ; Ribonucleotide reductase ; Protein subunit ; Genetics ; Cell biology ; DNA ; Gene Enzyme Structure and Function ; DNA Repair Mechanisms ; Protein Structure and Dynamics
Authors: Itamar Borges | Roberta M. P. O. Guimarães | Gabriel Monteiro‐de‐Castro | Nathália M. P. Rosa | Reed Niemann | Hans Lischka | Adélia J. A. Aquino
Source: ChemRxiv (preprint, 2023-05-15)
Field: Chemistry — Physical and Theoretical Chemistry

A comprehensive analysis of charge transfer effects on donor-pyrene (bridge)-acceptor systems using different substituents The alternant polycyclic aromatic hydrocarbon pyrene has photophysical properties that can be tuned with different donor and acceptor substituents. Recently, a D (donor) – Pyrene (bridge) – A (acceptor) system, DPA, with the electron donor N,N-dimethylaniline (DMA), and the electron acceptor trifluoromethylphenyl (TFM), was investigated by means of time-resolved spectroscopic measurements (J. Phys. Chem. Lett. 2021, 12, 2226−2231). DPA shows great promise for potential applications in organic electronic devices. In this work, we used the ab initio second-order algebraic diagrammatic construction method ADC(2) to investigate the excited-state properties of a series of analogous DPA systems, including the originally synthesized DPAs. The additionally investigated substituents were amino, fluorine, and methoxy as donors and nitrile and nitro groups as acceptors. The focus of this work was on characterizing the lowest excited singlet states regarding charge transfer (CT) and local excitation (LE) characters. For the DMA-pyrene-TFM system, the ADC(2) calculations show two initial electronic states relevant for interpreting the photodynamics. The bright S1 state is locally excited within the pyrene moiety, and an S2 state is localized ~0.5 eV above S1 and characterized as a donor to pyrene charge transfer state. Density functional theory HOMO and LUMO energies were employed to assess the efficiency of the DPA compounds for organic photovoltaics. HOMO-LUMO and optical gaps were used to estimate power conversion and light-harvesting efficiencies for practical applications in organic solar cells. From the systems using smaller D/A substituents, compounds with the strong acceptor NO2 substituent group show enhanced CT and promising properties for use in organic photovoltaics. HOMO/LUMO ; Acceptor ; Chemistry ; Photochemistry ; Excited state ; Density functional theory ; Pyrene ; Substituent ; Singlet state ; Organic solar cell ; Molecular orbital ; Time-dependent density functional theory ; Computational chemistry ; Atomic physics ; Stereochemistry ; Molecule ; Organic chemistry ; Polymer ; Physics Photochemistry and Electron Transfer Studies ; Organic Light-Emitting Diodes Research ; Organic Electronics and Photovoltaics
Authors: Marius Murariu | Fouad Laoutid | Yoann Paint | Oltea Murariu | Jean‐Marie Raquez | Philippe Dúbois
Source: International Journal of Molecular Sciences (article, 2023-08-10)
Field: Materials Science — Polymers and Plastics

Balancing the Strength–Impact Relationship and Other Key Properties in Polypropylene Copolymer–Natural CaSO4 (Anhydrite)-Filled Composites To develop novel mineral-filled composites and assess their enhanced properties (stiffness, a good balance between mechanical strength and impact resistance, greater temperature stability), a high-impact polypropylene copolymer (PPc) matrix containing an elastomeric discrete phase was melt mixed with natural CaSO<sub>4</sub> β-anhydrite II (AII) produced from gypsum rocks. First, in a prior investigation, the PPc composites filled with AII (without any modification) displayed enhanced stiffness, which is correlated with the relative content of the filler. The tensile and impact strengths dramatically decreased, especially at high filling (40 wt.%). Therefore, two key methods were considered to tune up their properties: (a) the ionomeric modification of PPc composites by reactive extrusion (REx) with zinc diacrylate (ZA), and (b) the melt mixing of PPc with AII surface modified with ethylenebis(stearamide) (EBS), which is a multifunctional processing/dispersant additive. The properties of composites produced with twin-screw extruders (TSEs) were deeply assessed in terms of morphology, mechanical, and thermal performance, including characterizations under dynamic mechanical solicitations at low and high temperatures. Two categories of products with distinct properties are obtained. The ionomeric modification by Rex (evaluated by FTIR) led to composites characterized by remarkable thermal stability, a higher temperature of crystallization, stronger interfacial interactions, and therefore noticeable mechanical properties (high tensile strength (i.e., 28 MPa), increased stiffness, moderate (3.3 kJ/m<sup>2</sup>) to good (5.0 kJ/m<sup>2</sup>) impact resistance) as well as advanced heat deflection temperature (HDT). On the other hand, the surface modification of AII with EBS facilitated the dispersion and debonding of microparticles, leading to composites revealing improved ductility (strain at break from 50% to 260%) and enhanced impact properties (4.3-5.3 kJ/m<sup>2</sup>), even at high filling. Characterized by notable mechanical and thermal performances, high whiteness, and a good processing ability, these new PPc-AII composites may be tailored to meet the requirements of end-use applications, ranging from packaging to automotive components. Materials science ; Composite material ; Ultimate tensile strength ; Izod impact strength test ; Polypropylene ; Thermal stability ; Extrusion ; Heat deflection temperature ; Surface modification ; Chemical engineering Polymer Nanocomposites and Properties ; biodegradable polymer synthesis and properties ; Polymer crystallization and properties
Authors: Juhee Kim | Wade F. Zeno
Source: Biophysical Journal (article, 2023-02-01)
Field: Materials Science — Materials Chemistry

The role of graphene quantum dots in mitigating lipid peroxidation Lipid peroxidation ; Trolox ; Ascorbic acid ; Chemistry ; Oxidative stress ; Biophysics ; Antioxidant ; Biochemistry ; Free-radical theory of aging ; Mitochondrion ; Biology ; Antioxidant capacity Carbon and Quantum Dots Applications ; Graphene and Nanomaterials Applications ; Advanced Nanomaterials in Catalysis
Authors: Shabnam Heydarzadeh | Sima Kheradmand Kia | Seti Boroomand | Mehdi Hedayati
Source:  (preprint, 2023-01-09)
Field: Materials Science — Biomaterials

Recent Developments in Cell Line Shipping Methods: Pivotal Gaps in Cellular Death Sciences Contrary to remarkable advances within the cell therapy industry, scientists expose dissatisfied challenges associated with the preservation and post-thaw cell death globally. Post cryopreservation apoptosis is normally observed in cultures and scientists are focusing on incorporation of apoptosis inhibitors. Impressive transport of cells without affecting their survival and function is a crucial and pivotal factor in any practical cell-based therapies. Preservation of cells permits the transportation of cells between distances, as well as improvement of safety and quality control testing in clinical and research applications. The prosperity of transportation methods is evaluated through the viability and proliferation percentages of the transported cell. For many decades, the conventional methods of transferring cells globally having adverse effects and speculated to be a challenging and expensive method. The main purpose of some studies is the optimization of cell survival after cryopreservation. In the new generation of cryopreservation science, various experiments wish to discover suitable and alternative methods for cell transportation to ship viable cells at ambient temperature without dry ice or in media filled flasks. In this review we try to represent a summary of the detection of recent studies including dry preservation, hypothermic preservation, agarose-gel based method, polymer based cryogel matrix, encapsulation method, fibrin microbeads, osmolyte solution composition, collagen-based scaffold, natural zwitterionic betaine, bio-inspired cryo-ink that have been performed alternative, effective and economic methods for shipping viable cells at ambient temperature. Cryopreservation ; Viability assay ; Cell encapsulation ; Apoptosis ; Programmed cell death ; Agarose ; Cell ; Cell biology ; Chemistry ; Nanotechnology ; Biotechnology ; Biology ; Materials science ; Biochemistry Electrospun Nanofibers in Biomedical Applications ; Tissue Engineering and Regenerative Medicine ; Pluripotent Stem Cells Research