jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Martin N. Muigano | Sylvester Anami | Justus M. Onguso | Godfrey O. Mauti
Source: International Journal of Polymer Science (article, 2024-01-01)
Field: Materials Science — Biomaterials

Optimized Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) Production by Moderately Haloalkaliphilic Bacterium <i>Halomonas alkalicola</i> Ext Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polymers that are produced by microorganisms as storage materials under limited nutrition and excess carbon. These PHAs have been found to be ideal for replacing synthetic plastics for use in packaging and biomedical applications. In this study, an alkaliphilic and moderately halophilic bacterium Halomonas alkalicola Ext was isolated from Lake Simbi Nyaima in western Kenya and investigated for PHA production. Sudan Black B and Nile Red A staining showed that bacterium had distinct ability for accumulation of PHAs. To optimize PHA production, the bacterium was grown in submerged fermentation under varying culture conditions and different sources and concentrations of carbon and nitrogen. With one‐factor‐at‐a‐time (OFTA) approach, optimal PHA yields were obtained after 72 hours at a pH of 10.0, temperature of 35°C, and 2.5% ( w / v ) NaCl. The bacterium yielded the highest biomass, and PHA amounts on 2% galactose and 0.1% ammonium sulfate as sources of carbon and nitrogen, respectively. A record PHA yield of 0.071 g g -1 with a titer of 1.419 ± 0.09 g/L was achieved from 3.397 g/L of biomass, equivalent to 41.8% PHA content. Using response surface methodology, PHA titer was increased by 1.5% to 1.44 g/L, while PHA content was improved 1.1‐fold to 45.57%. Polymer analysis revealed that the extracted PHA was a poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) (3 − HB : 3 − HV = 92 : 8) with two copolymer subunits of 3‐hydroxyvaryrate (3‐HB) and 3‐hydroxybutyrate (3‐HV). Halomonas alkalicola Ext attained efficient galactose conversion into PHBV under high salinity and alkalinity conditions. Polyhydroxyalkanoates ; Halomonas ; Bacteria ; Ammonium ; Ammonia ; Food science ; Nuclear chemistry ; Biomass (ecology) ; Microorganism ; Titer ; Nitrogen ; Fermentation ; Halophile ; Biology ; Chemistry ; Biochemistry ; Organic chemistry ; Ecology biodegradable polymer synthesis and properties ; Microplastics and Plastic Pollution
Authors: Jian Luo | Michael T. Davenport | Daniel H. Ess | Tianbiao Liu
Source: Angewandte Chemie International Edition (article, 2024-06-08)
Field: Chemistry — Organic Chemistry

Nickel‐Catalyzed Electrochemical Cross‐Electrophile C(sp<sup>2</sup>)−C(sp<sup>3</sup>) Coupling via a Ni<sup>II</sup> Aryl Amido Intermediate Cross-electrophile coupling (XEC) between aryl halides and alkyl halides is a streamlined approach for C(sp<sup>2</sup>)-C(sp<sup>3</sup>) bond construction, which is highly valuable in medicinal chemistry. Based on a key Ni<sup>II</sup> aryl amido intermediate, we developed a highly selective and scalable Ni-catalyzed electrochemical XEC reaction between (hetero)aryl halides and primary and secondary alkyl halides. Experimental and computational mechanistic studies indicate that an amine secondary ligand slows down the oxidative addition process of the Ni-polypyridine catalyst to the aryl bromide and a Ni<sup>II</sup> aryl amido intermediate is formed in situ during the reaction process. The relatively slow oxidative addition is beneficial for enhancing the selectivity of the XEC reaction. The Ni<sup>II</sup> aryl amido intermediate stabilizes the Ni<sup>II</sup>-aryl species to prevent the aryl-aryl homo-coupling side reactions and acts as a catalyst to activate the alkyl bromide substrates. This electrosynthesis system provides a facile, practical, and scalable platform for the formation of (hetero)aryl-alkyl bonds using standard Ni catalysts under mild conditions. The mechanistic insights from this work could serve as a great foundation for future studies on Ni-catalyzed cross-couplings. Nickel ; Aryl ; Electrophile ; Catalysis ; Chemistry ; Electrochemistry ; Coupling (piping) ; Coupling reaction ; Combinatorial chemistry ; Polymer chemistry ; Organic chemistry ; Materials science ; Alkyl ; Physical chemistry Catalytic Cross-Coupling Reactions ; Radical Photochemical Reactions ; Catalytic C–H Functionalization Methods
Authors: Nilam Shah | Tianjiu Zhu | Desheng Feng | Xiaoyong Xu | Fengli Liang | Hao Wang | Zhonghua Zhu | Lei Ge
Source: Journal of Power Sources (article, 2024-08-06)
Field: Materials Science — Materials Chemistry

Fine-tuning thermal expansion characteristics of solid oxide fuel cell cathode via composite cathode fabrication Solid oxide fuel cells (SOFCs) offer promising prospects for sustainable electricity generation, attributed to high efficiency and fuel adaptability. However, their widespread application relies on three critical factors: performance, cost-effectiveness, and durability. Durability presents a significant hurdle; one key reason is the thermal expansion mismatch between cobalt-based cathodes and electrolytes, potentially leading to detachment at the cathode-electrolyte interface. In this study, we propose an approach to mitigate this challenge by fine-tuning the thermal expansion characteristics of the cathode. By tailoring lattice and chemical expansion, our composite cathode incorporates recognized materials like Ba0·5Sr0·5Co0·8Fe0·2O3-δ with Sm0.2Ce0·8O1.9 and the negative thermal expansion (NTE) material Y2W3O12. Through the design of composite materials, we achieve enhanced thermal cycling stability with only ∼20 % area-specific resistance (ASR) increases after 40 harsh thermal cycles between 300–600 °C compared to pure BSCF with over 100 % increment. This optimization process effectively reduces the thermal expansion coefficient while preserving BSCF's overall properties, offering a promising path for supporting SOFC durability and performance. Cathode ; Durability ; Thermal expansion ; Materials science ; Solid oxide fuel cell ; Electrolyte ; Oxide ; Composite number ; Composite material ; Chemical engineering ; Electrode ; Chemistry ; Metallurgy ; Electrical engineering ; Engineering Advancements in Solid Oxide Fuel Cells ; Electronic and Structural Properties of Oxides ; Thermal Expansion and Ionic Conductivity
Authors: Marco Galeotti | Massimo Bietti | Miguel Costas
Source: Journal of the American Chemical Society (article, 2024-03-20)
Field: Chemistry — Inorganic Chemistry

Catalyst and Medium Control over Rebound Pathways in Manganese-Catalyzed Methylenic C–H Bond Oxidation The C(sp<sup>3</sup>)-H bond oxygenation of a variety of cyclopropane containing hydrocarbons with hydrogen peroxide catalyzed by manganese complexes containing aminopyridine tetradentate ligands was carried out. Oxidations were performed in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and 2,2,2-trifluoroethanol (TFE) using different manganese catalysts and carboxylic acid co-ligands, where steric and electronic properties were systematically modified. Functionalization selectively occurs at the most activated C-H bonds that are α- to cyclopropane, providing access to carboxylate or 2,2,2-trifluoroethanolate transfer products, with no competition, in favorable cases, from the generally dominant hydroxylation reaction. The formation of mixtures of unrearranged and rearranged esters (oxidation in HFIP in the presence of a carboxylic acid) and ethers (oxidation in TFE) with full control over diastereoselectivity was observed, confirming the involvement of delocalized cationic intermediates in these transformations. Despite such a complex mechanistic scenario, by fine-tuning of catalyst and carboxylic acid sterics and electronics and leveraging on the relative contribution of cationic pathways to the reaction mechanism, control over product chemoselectivity could be systematically achieved. Taken together, the results reported herein provide powerful catalytic tools to rationally manipulate ligand transfer pathways in C-H oxidations of cyclopropane containing hydrocarbons, delivering novel products in good yields and, in some cases, outstanding selectivities, expanding the available toolbox for the development of synthetically useful C-H functionalization procedures. Chemistry ; Cyclopropane ; Steric effects ; Catalysis ; Cationic polymerization ; Chemoselectivity ; Ligand (biochemistry) ; Carboxylate ; Carboxylic acid ; Allylic rearrangement ; Electronic effect ; Combinatorial chemistry ; Manganese ; Organic chemistry Metal-Catalyzed Oxygenation Mechanisms ; Oxidative Organic Chemistry Reactions ; Catalytic C–H Functionalization Methods
Authors: Tao Pan | Xinnian Jiang | Eveline R. W. van Doremaele | Junyu Li | Tom P. A. van der Pol | Chenshuai Yan | Gang Ye | Jian Liu | Wenjing Hong | Ryan C. Chiechi | Yoeri van de Burgt | Yanxi Zhang
Source: Advanced Science (article, 2024-05-29)
Field: Materials Science — Polymers and Plastics

Over 60 h of Stable Water‐Operation for N‐Type Organic Electrochemical Transistors with Fast Response and Ambipolarity Organic electrochemical transistors (OECTs) are of great interest in low-power bioelectronics and neuromorphic computing, as they utilize organic mixed ionic-electronic conductors (OMIECs) to transduce ionic signals into electrical signals. However, the poor environmental stability of OMIEC materials significantly restricts the practical application of OECTs. Therefore, the non-fused planar naphthalenediimide (NDI)-dialkoxybithiazole (2Tz) copolymers are fine-tuned through varying ethylene glycol (EG) side chain lengths from tri(ethylene glycol) to hexa(ethylene glycol) (namely P-XO, X = 3-6) to achieve OECTs with high-stability and low threshold voltage. As a result, the NDI-2Tz copolymers exhibit ambipolarity, rapid response (<10 ms), and ultra-high n-type stability. Notably, the P-6O copolymers display a threshold voltage as low as 0.27 V. They can operate in n-type mode in an aqueous solution for over 60 h, maintaining an on-off ratio of over 10<sup>5</sup>. This work sheds light on the design of exceptional n-type/ambipolar materials for OECTs. It demonstrates the potential of incorporating these ambipolar polymers into water-operational integrated circuits for long-term biosensing systems and energy-efficient brain-inspired computing. Bioelectronics ; Ethylene glycol ; Ambipolar diffusion ; Materials science ; Ionic bonding ; Electrochemistry ; Transistor ; Aqueous solution ; Copolymer ; Nanotechnology ; Optoelectronics ; Polymer ; Voltage ; Ion ; Biosensor ; Chemistry ; Electrical engineering ; Organic chemistry ; Physics ; Electron ; Electrode Conducting polymers and applications ; Advanced Sensor and Energy Harvesting Materials ; Advanced Memory and Neural Computing
Authors: Alison Sy-min Chang | Melanie A. Kascoutas | Quinn Valentine | Kiera How | Rachel Thomas | Amanda K. Cook
Source: Journal of the American Chemical Society (article, 2024-05-21)
Field: Chemistry — Inorganic Chemistry

Alkene Isomerization Using a Heterogeneous Nickel-Hydride Catalyst Transition metal-catalyzed alkene isomerization is an enabling technology used to install an alkene distal to its original site. Due to their well-defined structure, homogeneous catalysts can be fine-tuned to optimize reactivity, stereoselectivity, and positional selectivity, but they often suffer from instability and nonrecyclability. Heterogeneous catalysts are generally highly robust but continue to lack active-site specificity and are challenging to rationally improve through structural modification. Known single-site heterogeneous catalysts for alkene isomerization utilize precious metals and bespoke, expensive, and synthetically intense supports. Additionally, they generally have mediocre reactivity, inspiring us to develop a heterogeneous catalyst with an active site made from readily available compounds made of Earth-abundant elements. Previous work demonstrated that a very active homogeneous catalyst is formed upon protonation of Ni[P(OEt)<sub>3</sub>]<sub>4</sub> by H<sub>2</sub>SO<sub>4</sub>, generating a [Ni-H]<sup>+</sup> active site. This catalyst is incredibly active, but also decomposes readily, which severely limits its utility. Herein we show that by using a solid acid (sulfated zirconia, SZO<sub>300</sub>), not only is this decomposition prevented, but high activity is maintained, improved selectivity is achieved, and a broader scope of functional groups is tolerated. Preliminary mechanistic experiments suggest that the catalytic reaction likely goes through an intermolecular, two-electron pathway. A detailed kinetic study comparing the state-of-the-art Ni and Pd isomerization catalysts reveals that the highest activity and selectivity is seen with the Ni/SZO<sub>300</sub> system. The reactivity of Ni/SZO<sub>300</sub>, is not limited to alkene isomerization; it is also a competent catalyst for hydroalkenylation, hydroboration, and hydrosilylation, demonstrating the broad application of this heterogeneous catalyst. Isomerization ; Alkene ; Chemistry ; Catalysis ; Reactivity (psychology) ; Protonation ; Heterogeneous catalysis ; Photochemistry ; Hydride ; Combinatorial chemistry ; Selectivity ; Organic chemistry ; Metal Asymmetric Hydrogenation and Catalysis ; Catalytic C–H Functionalization Methods ; Catalytic Cross-Coupling Reactions
Authors: Barak Ratzker | Bar Favelukis | Mark Baranov | Yugal Rathod | Avia Greenberg | Or Messer | Dor A. Goldstein | Alexander Upcher | Vladimir Ezersky | Nitzan Maman | Ido Biran | Varun Natu | Maxim Sokol
Source: Advanced Functional Materials (article, 2024-06-26)
Field: Materials Science — Materials Chemistry

Synthesis of Ti <sub>1‐x</sub> W <sub>x</sub> Solid Solution MAX Phases and Derived MXenes for Sodium‐Ion Battery Anodes Abstract A distinguishing feature of MAX phases and their MXene derivatives is their remarkable chemical diversity. This diversity, coupled with the 2D nature of MXenes, positions them as outstanding candidates for a wide range of electrochemical applications. Chemical disorder introduced by a solid solution can improve electrochemical behavior. Up to now, adding considerable amount of tungsten (W) in MAX phase and MXenes solid solutions, which can enhance electrochemical performance, proved challenging. In this study, the synthesis of M site Ti 1‐x W x solid solution MAX phases are reported. The 211‐type (Ti 1‐x W x ) 2 AlC exhibits a disordered solid solution, whereas the 312‐type (Ti 1‐x W x ) 3 AlC 2 displays a near‐ordered structure, resembling o ‐MAX, with W atoms preferentially occupying the outer planes. Solid‐solution MXenes, Ti 2.4 W 0.6 C 2 T z , and Ti 1.6 W 0.4 CT z , are synthesized via selective etching of high‐purity MAX powder precursors containing 20% W. These MXenes are evaluated as sodium‐ion battery anodes, with Ti 1.6 W 0.4 CT z showing exceptional capacity, outperforming existing multilayer MXene chemistries. This work not only demonstrates the successful integration of W in meaningful quantities into a double transition metal solid solution MAX phase, but also paves the way for the development of cost‐effective MXenes containing W. Such advancements significantly widen their application spectrum by fine‐tuning their physical, electronic, mechanical, electrochemical, and catalytic properties. MXenes ; Materials science ; Solid solution ; Ion ; Sodium ; MAX phases ; Sodium-ion battery ; Anode ; Battery (electricity) ; Analytical Chemistry (journal) ; Nanotechnology ; Carbide ; Thermodynamics ; Physical chemistry ; Metallurgy ; Faraday efficiency ; Electrode ; Physics MXene and MAX Phase Materials ; Advancements in Battery Materials ; Advanced Memory and Neural Computing
Authors: Zhenmin Li | Baosen Mi | Xun Ma | Ping Liu | Fengcang Ma | Ke Zhang | Xiaohong Chen | Xinfa Zhu | Yi Meng | LU Hong-mei | Wei Li
Source: Vacuum (article, 2024-07-31)
Field: Materials Science — Materials Chemistry

Preparation and characterization of chromium oxide thin films: The response of morphology, crystal structure, and electrical properties to oxygen pressure under magnetron sputtering Partial pressure ; Materials science ; Sputtering ; Sputter deposition ; Microstructure ; Oxygen ; Oxide ; Chromium ; Doping ; Stoichiometry ; Cavity magnetron ; Thin film ; Chemical engineering ; Analytical Chemistry (journal) ; Nanotechnology ; Metallurgy ; Optoelectronics ; Chemistry ; Physical chemistry ZnO doping and properties ; Advanced Photocatalysis Techniques ; Copper-based nanomaterials and applications
Authors: Z. Y. Khattari
Source: Optical Materials (article, 2024-02-20)
Field: Materials Science — Materials Chemistry

Lie crystallographic symmetry, radiation shielding, and optical characteristics of SiO2: Insights into universal behavior and material optimization Tetragonal crystal system ; Crystal (programming language) ; Polarizability ; Crystallography ; Materials science ; Intermolecular force ; Crystal structure ; Orthorhombic crystal system ; Molecular physics ; Chemistry ; Physics ; Quantum mechanics ; Molecule X-ray Diffraction in Crystallography ; Crystal Structures and Properties ; High-pressure geophysics and materials
Authors: Xuanwei Zhao | Baoqin Fu | Ran Ang
Source: Advanced Functional Materials (article, 2024-04-23)
Field: Materials Science — Materials Chemistry

Manipulating Pb Vacancies Achieved Ultra‐High Thermoelectrics in Quaternary Pb<sub>0.95</sub>Na<sub>0.04</sub>Te<sub>1‐</sub><i><sub>x</sub></i>Se<i><sub>x</sub></i> via Fine‐Tuning Se Solubility Abstract Optimizing carrier concentration in PbTe materials can be achieved effectively through the chemical doping of sodium. Nevertheless, the valence balance can lead to the presence of “deleterious defects” in the PbTe matrix, resulting in low sodium solubility at room temperature. Herein, a strategy for fine‐tuning Pb vacancies to improve sodium solubility is developed. By a trace amount of Se‐doping, the solubility of Na in Pb 0.99 Te 1‐ x Se x through the preservation of Pb vacancies in the matrix is substantially increased. Additionally, a large number of dense dislocations in the grains, which greatly reduced the lattice thermal conductivity is induced. A high power factor of ≈26 mW cm −1 K −2 and low lattice thermal conductivity of ≈0.43 W m −1 K −1 at 823 K in Pb 0.95 Na 0.04 Te 0.97 Se 0.03 is achieved. Ultimately, a high figure of merit, ZT ≈2.2, is obtained at 823 K in quaternary PbTe compound. The current findings not only demonstrate that the introduction of trace amounts of Se and Pb vacancies in the PbTe matrix can effectively enhance Na solubility and minimize thermal conductivity, attaining synergistic improvement in electrical and thermal properties, but also indicate that the synergistic effect of Pb vacancies with a specific dopant is an alternative approach for enhancing ZT . Materials science ; Solubility ; Dopant ; Doping ; Thermoelectric effect ; Valence (chemistry) ; Electrical resistivity and conductivity ; Analytical Chemistry (journal) ; Thermoelectric materials ; Thermal conductivity ; Solid solution ; Physical chemistry ; Thermodynamics ; Metallurgy ; Optoelectronics ; Composite material ; Chemistry Advanced Thermoelectric Materials and Devices ; Chalcogenide Semiconductor Thin Films ; Thermal properties of materials
Authors: Cuixia Bi | Xiaolong Yin | Hongyan Zhao
Source: RSC Advances (article, 2024-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Synthesis of Au@Ag core–shell nanocubes with finely tuned shell thicknesses for surface-enhanced Raman spectroscopic detection In this work, we describe a facile method for generating monodisperse Au@Ag core-shell nanocubes with well-controlled size and fine-tuned Ag shell thicknesses. In this synthesis method, Au nanocubes were prepared <i>via</i> the seed-mediated growth method. Then, Au@Ag nanocubes with the core-shell structure were prepared separately by reducing AgNO<sub>3</sub> with AA using as-prepared Au nanocubes as seeds. The thickness of Ag shells could be finely tuned from 3.6 nm to 10.0 nm by varying the concentration of the AgNO<sub>3</sub> precursor. By investigating the localized surface plasmon resonance (LSPR) properties of Au@Ag nanocubes in relation to the thickness of the Ag shell, we found that the intensity of the characteristic peak of Ag gradually increases and that of Au gradually decreases as the thickness of the Ag shell increases. Additionally, surface-enhanced Raman scattering (SERS) properties of Au@Ag core-shell nanocubes were evaluated using rhodamine 6G (R6G) as the probe molecule. Interestingly, Au@Ag nanocubes exhibit efficient SERS intensities compared to the Au nanocubes, and Ag shell with a thickness of about 8.4 nm exhibits the optimal SERS activity. In addition, our results also demonstrated that Au@Ag nanocubes with an Ag shell thickness of 8.4 nm exhibited high SERS sensitivity and are capable of probing the analyte down to 10<sup>-12</sup> M. The results obtained here suggest that Au@Ag core-shell nanocubes might serve as a nanoprobe for SERS-based analytical and biosensing applications. Shell (structure) ; Raman spectroscopy ; Materials science ; Core (optical fiber) ; Nanotechnology ; Surface (topology) ; Chemical engineering ; Surface-enhanced Raman spectroscopy ; Raman scattering ; Optics ; Composite material Gold and Silver Nanoparticles Synthesis and Applications ; Advanced Nanomaterials in Catalysis ; Nanocluster Synthesis and Applications
Authors: Subhra Kanti De | T.K. Aparna | K. R. Gopi Krishna | Somnath Bhattacharyya
Source: Chemical Engineering Journal (article, 2024-12-23)
Field: Materials Science — Materials Chemistry

Enhancing the electrochemical performance of TiVCTx MXene by tuning termination groups through different synthesis routes Electrochemistry ; Materials science ; Nanotechnology ; Chemistry ; Electrode MXene and MAX Phase Materials ; Advanced Memory and Neural Computing ; 2D Materials and Applications
Authors: Krister Holmberg | Frida Bilén | Romain Bordes
Source: Current Opinion in Colloid & Interface Science (article, 2024-11-29)
Field: Chemistry — Organic Chemistry

Development of amino acid-based surfactants: from synthesis to applications The diversity of both natural and non-natural amino acids provides a strong foundation for the synthesis of a wide array of surfactants and offers the possibility to control the interactions at interfaces and within self-assembly processes. This review provides an overview of the latest developments of amino acid-based surfactant over the past decade, with a particular focus on the past five years. A detailed overview of the synthesis is first given, and physicochemical properties of surfactants derived from both standard amino acids, and non-natural amino acids are discussed. From enhancing foaming to controlling rheological properties, these surfactants meet a wide range of application-specific requirements. This is illustrated in various fields, such as drug delivery or mineral ore flotation. Although single amino acid derivatives have been deeply explored, surfactants based on multiple amino acids are also discussed for the new possibilities in self-assembly and potential various applications they offer. Chemistry ; Amino acid ; Biochemical engineering ; Combinatorial chemistry ; Biochemistry ; Engineering Surfactants and Colloidal Systems ; Analytical Chemistry and Chromatography ; Environmental Chemistry and Analysis