475 results match your criteria: "Materials and Process Simulation Center[Affiliation]"

Ensuring the stability of electrocatalysts is paramount to the success of electrochemical energy conversion devices. Degradation is a fundamental process involving the release of positively charged metal ions into the electric double layer (EDL) and their subsequent diffusion into the bulk electrolyte. However, despite its vital importance in achieving prolonged electrocatalysis, the underlying causality of catalyst dissolution with the EDL structure remains largely unknown.

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Molecular Strain Accelerates Electron Transfer for Enhanced Oxygen Reduction.

J Am Chem Soc

January 2025

Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong 999077, P. R. China.

Fe-N-C materials are emerging catalysts for replacing precious platinum in the oxygen reduction reaction (ORR) for renewable energy conversion. However, their potential is hindered by sluggish ORR kinetics, leading to a high overpotential and impeding efficient energy conversion. Using iron phthalocyanine (FePc) as a model catalyst, we elucidate how the local strain can enhance the ORR performance of Fe-N-Cs.

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Electrochemical energy storage plays a critical role in the transition to clean energy. With the growing demand for efficient and sustainable energy solutions, supercapacitors have gained significant attention due to their high specific capacitance, rapid charge/discharge capabilities, long lifespan, safe operation across various temperatures, and minimal maintenance needs. This study introduces a novel approach for the synthesis of high-performance supercapacitor electrodes by using MnNi-MOF-74 as a precursor.

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Electrochemical nitrate reduction to ammonia (NORR) is promising to not only tackle environmental issues caused by nitrate but also produce ammonia at room temperatures. However, two critical challenges are the lack of effective electrocatalysts and the understanding of related reaction mechanisms. To overcome these challenges, we employed first-principles calculations to thoroughly study the performance and mechanisms of triple-atom catalysts (TACs) composed of transition metals (including 27 homonuclear TACs and 4 non-noble bimetallic TACs) anchored on N-doped carbon (NC).

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Mimicking the superstructures and properties of spherical biological encapsulants such as viral capsids and ferritin offers viable pathways to understand their chiral assemblies and functional roles in living systems. However, stereospecific assembly of artificial polyhedra with mechanical properties and guest-binding attributes akin to biological encapsulants remains a formidable challenge. Here we report the stereospecific assembly of dynamic supramolecular snub cubes from 12 helical macrocycles, which are held together by 144 weak C-H hydrogen bonds.

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Metabotropic GABA Receptor Activation Induced by G Protein Coupling.

J Am Chem Soc

January 2025

Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States.

G protein-coupled receptors (GPCRs) play central roles in regulating cellular responses through heterotrimeric G proteins (GP). Extensive studies have elucidated the complex cellular signaling mediated by GPCRs that accompany dynamic conformational changes upon activation. However, there has been less focus on the role of the GP on the activation process, particularly for class C GPCRs that function as obligate dimers.

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The iridium oxide (IrO) catalyst for the oxygen evolution reaction used industrially (in proton exchange membrane water electrolyzers) is scarce and costly. Although ruthenium oxide (RuO) is a promising alternative, its poor stability has hindered practical application. We used well-defined extended surface models to identify that RuO undergoes structure-dependent corrosion that causes Ru dissolution.

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A General Nonbonded Force Field Based on Accurate Quantum Mechanics Calculations for Elements H-La and Hf-Rn.

J Chem Theory Comput

January 2025

Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States.

Noncovalent interactions (NCI) play a central role in numerous physical, chemical, and biological phenomena. An accurate description of NCI is the key to success for any theoretical study in such areas. Although quantum mechanics (QM) methods such as dispersion-corrected density functional theory are sufficiently accurate, their applications are practical only for <300 atoms and <100 ps of simulation time.

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Subtle Modifications in Interface Configurations of Iron/Cobalt Phthalocyanine-Based Electrocatalysts Determine Molecular CO Reduction Activities.

Angew Chem Int Ed Engl

November 2024

Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR, 999077, P. R. China.

Strain engineering has emerged as a powerful approach in steering material properties. However, the mechanism and potential limitations remain poorly understood. Here we report that subtle changes in molecular configurations can profoundly affect, conducively or adversely, the catalytic selectivity and product turnover frequencies (TOFs) of CO reduction reaction.

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Parameterization and quantification of two key operando physio-chemical descriptors for water-assisted electro-catalytic organic oxidation.

Nat Commun

November 2024

Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu, China.

Electro-selective-oxidation using water as a green oxygen source demonstrates promising potential towards efficient and sustainable chemical upgrading. However, surface micro-kinetics regarding co-adsorption and reaction between organic and oxygen intermediates remain unclear. Here we systematically study the electro-oxidation of aldehydes, alcohols, and amines on Co/Ni-oxyhydroxides with multiple characterizations.

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G protein-coupled receptors (GPCRs) regulate multiple cellular responses and represent highly successful therapeutic targets. The mechanisms by which agonists activate the G protein are unclear for many GPCR families, including the bitter taste receptors (TAS2Rs). We ascertained TAS2R5 properties by live cell-based functional assays, direct binding affinity measurements using optical resonators, and atomistic molecular dynamics simulations.

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How Rigid Are Anthranilamide Molecular Electrets?

J Phys Chem B

November 2024

Department of Bioengineering, University of California, Riverside, California 92521, United States.

Article Synopsis
  • Molecular electrets are crucial for electronic materials, but their properties are affected by conformational fluctuations that alter their macrodipoles.
  • Using molecular dynamics simulations with the polarizable charge equilibrium method, researchers investigate the persistence length of anthranilamide-based molecular electrets.
  • The study reveals that the rigidity of these macromolecules varies along their structure and is influenced by solvent polarity, impacting their potential applications in organic electronics and energy systems.
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Methanol Formation in Hyperthermal Oxygen Collisions with Methane Clathrate Ice.

J Phys Chem A

November 2024

Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States.

Article Synopsis
  • - The study investigates how hyperthermal reactive ions, specifically water group molecules, affect the organic chemistry of icy bodies, which could be important for understanding prebiotic conditions.
  • - Molecular dynamics simulations reveal that irradiating carbon-bearing ice with atomic oxygen primarily produces methanol, suggesting a unique hot-atom reaction mechanism, especially at lower doses.
  • - At higher irradiation doses, the chemical composition shifts towards more oxidized carbon compounds, with formaldehyde becoming more prevalent than methanol, indicating varying effects of different impactors and guest species on the ice chemistry.
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The high carbon intensity of present-day ethylene glycol (EG) production motivates interest in electrifying ethylene oxidation. Noting poor kinetics in prior reports of the organic electrooxidation of small hydrocarbons, we explored the design of mediators that activate and simultaneously stabilize light alkenes. A ruthenium-substituted polyoxometalate (Ru-POM, {Si[Ru(HO)WO]}) achieves 82% faradaic efficiency in EG production at 100 mA/cm under ambient conditions.

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Realizing high selectivity for producing biodegradable 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF) for renewable polymers from 5-hydroxymethylfurfural (HMF) biomass through ring hydrogenation on single-atom catalysts poses a considerable challenge due to the complexity of HMF functional groups and the difficulty of H dissociation. We developed a detailed reaction mechanism based on molecular dynamics (AIMD) and quantum mechanics (QM) to find that Ru single-atom catalysts can simultaneously dissociate H and perform the ring hydrogenation of biomass-derived 2,5-bis(hydroxymethyl)furan (BHMF) to produce biodegradable BHMTHF, with a free energy barrier of 0.82 eV.

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We have developed a class of phosphido-boranes (BoPh's) with formula X[RPBH] that bind CO with exceptional strength (Δ = -8.2 to -24.0 kcal/mol) at ambient conditions.

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Article Synopsis
  • * The study examines how various sweet substances, including steviol glycosides and artificial sweeteners, interact with different binding sites on the sweet taste receptor using experimental and computational methods.
  • * Results show that steviol glycosides can change the receptor's affinity by binding to specific intracellular regions, enhancing our understanding of the receptor's structure and function.
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Synthesis and Magnetic Properties of Spherical Maghemite Nanoparticles with Tunable Size and Surface Chemistry.

Langmuir

October 2024

CNRS, De la Molécule aux Nano-Objets: Réactivité, Interactions Spectroscopies, MONARIS, Sorbonne Université, 75005 Paris, France.

We report the synthesis of uniform populations of spherical maghemite nanoparticles by thermal decomposition of iron precursors with tunable diameters centered at 3.3, 7.5, and 12.

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Optimizing QLED Performance and Stability via the Surface Modification of PEDOT:PSS Experimental Insights and DFT Calculations.

ACS Appl Mater Interfaces

October 2024

School of Chemical Engineering, Sungkyunkwan University (SKKU), 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea.

Article Synopsis
  • The presence of polystyrenesulfonate (PSS) in PEDOT:PSS negatively impacts charge transfer in quantum dot light-emitting diodes (QLEDs).
  • A two-step solvent treatment significantly reduced PSS by 40%, enhancing the conductivity of PEDOT due to weaker ionic interactions facilitated by ethylene glycol.
  • Following the treatment, improved electroluminescence performance was observed in InP QLEDs, achieving an external quantum efficiency of 6.4% and an operational lifetime of 125.6 hours.
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Stress, such as neuroexcitotoxicity and oxidative stress, as well as traumatic brain injury, will result in neurodegeneration. Deciphering the mechanisms underlying neuronal cell death will facilitate the development of drugs that can promote neuronal survival and repair through neurogenesis. Many growth and trophic factors, including transforming growth factors (TGFs), insulin-like growth factors (IGFs), epidermal growth factor (EGF), fibroblast growth factor 2 (FGF2), and brain-derived neurotrophic factor (BDNF), are known to play a role in neuroprotection and neurogenesis.

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Under reducing conditions, SrTiO perovskite can exchange up to 20% of its O ions for H (hydride), greatly influencing its material properties. This not only presents intriguing possibilities for material design, but also for hydrogen sequestration in the deep earth, where perovskite-structured minerals are abundant. However, uncertainties remain surrounding hydride incorporation in SrTiO, including details of the hydride structural state, and how hydride interacts with the broader defect chemistry of SrTiO.

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Ligand-Dependent and G Protein-Dependent Properties for the Sweet Taste Heterodimer, TAS1R2/1R3.

J Phys Chem B

September 2024

Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, California 91125, United States.

The heterodimeric sweet taste receptor, TAS1R2/1R3, is a class C G protein-coupled receptor (GPCR) that couples to gustducin (Gt), a G protein (GP) specifically involved in taste processing. This makes TAS1R2/1R3 a possible target for newly developing low caloric ligands that taste sweet to address obesity and diabetes. The activation of TAS1R2/1R3 involves the insertion of the GαP C-terminus of the GP into the GPCR in response to ligand binding.

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Functionalized Amorphous Carbon Materials via Reactive Molecular Dynamics Simulations.

ACS Appl Mater Interfaces

September 2024

Consiglio Nazionale delle Ricerche, CNR-ICCOM, Pisa 56124, Italy.

We derive a database of atomistic structural models of amorphous carbon materials endowed with exohedral functional groups. We start from phases previously derived using the DynReaxMas method for reactive molecular dynamics simulations, which exhibit atomistic and medium-length-scale features in excellent agreement with available experimental data. Given a generic input structure/phase, we develop postprocessing simulation algorithms mimicking experimental preparation protocols aimed at: (1) "curing" the phase to decrease the defect concentration; (2) automatically selecting the most reactive carbon atoms via interaction with a probe molecular species, and (3) stabilizing the phase by saturating the valence of carbon atoms with single-bond functional groups.

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Next-generation batteries based on more sustainable working ions could offer improved performance, safety, and capacity over lithium-ion batteries while also decreasing the cost. Development of next-generation battery technology using "beyond-Li" mobile ions, especially multivalent ions, is limited due to a lack of understanding of solid state conduction of these ions. Here, we introduce ligand-coordinated ions in PS-based (M = Mn, Cd) solid host crystals to simultaneously increase the size of the interlayer spacing, through which the ions can migrate, and screen the charge-dense ions.

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Electrochemical Properties of MoVCT MXene in Aqueous Electrolytes.

ACS Appl Mater Interfaces

July 2024

Department of Mechanical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong 19104, China.

MCT MXenes represent the most recently discovered and least studied subfamily of out-of-plane ordered double transition metal carbides with 11 atomic layers, probably the thickest of all 2D materials. Molybdenum (Mo) and vanadium (V) in MoVCT offer multiple oxidation states, making this MXene potentially attractive for electrochemical energy storage applications. Herein, we evaluated the electrochemical properties of MoVCT free-standing thin films in acidic, basic, and neutral aqueous electrolytes and observed the highest gravimetric capacitance of 219 F g at 2 mV s in a 3 M HSO.

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