Physical and Theoretical Chemistry

Identifying the most constraining ice observations to infer molecular binding energies

This astrochemistry paper addresses the challenge of poorly constrained molecular binding energies on interstellar dust grains, crucial for understanding complex organic molecule formation. Using the MOPED algorithm, the authors identify specific ice species whose observations, particularly with improved precision, would best constrain these binding energies. The study recommends prioritizing more precise measurements of already detected species like H2O, CO2, and CH3OH, alongside targeting species such as HCN and H2S.

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Physical and Theoretical Chemistry Sep 28, 11:22 AM

Phase behavior of Cacio e Pepe sauce

This study explores the science behind Cacio e Pepe, demonstrating how starch concentration in the pasta water prevents cheese clumping. The researchers identified a "Mozzarella Phase" where low starch leads to large, undesirable clumps and found that trisodium citrate can also stabilize the sauce, albeit with a slight flavor trade-off.

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Physical and Theoretical Chemistry Sep 19, 07:06 PM

σ- vs π-Binding: Lewis Acids Bind Lone Pairs, Not Double Bonds

This computational study reveals that Lewis acids strongly prefer to bind to lone pairs of electrons (σ-binding) rather than double bonds (π-binding) in molecules like acrolein and azabutadiene. This preference holds true across various Lewis acids, solvents, and even influences reaction pathways like the Diels-Alder reaction.

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Physical and Theoretical Chemistry Sep 19, 03:07 PM

ILVES: Accurate and Efficient Bond Length and Angle Constraints in Molecular Dynamics

This computational chemistry paper introduces ILVES, a new family of algorithms for molecular dynamics simulations. ILVES improves the accuracy and efficiency of constraining bond lengths and enables constraining hydrogen bond angles, allowing for a larger time step (3.5 fs) and 1.65x faster simulations compared to current methods.

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Physical and Theoretical Chemistry Sep 12, 10:16 AM

An 18-Porphyrin Nanoring at the Size Limit for Global Aromaticity

Researchers synthesized an 18-porphyrin nanoring, the largest molecule to date exhibiting evidence of global aromaticity. Using NMR and computational modelling, they found weak ring currents, which suggest that this size is close to the limit for this phenomenon. These findings highlight the role of size and conformation in molecular magnetism.

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Physical and Theoretical Chemistry Aug 29, 04:37 PM

Interfaces govern the structure of angstrom-scale confined water solutions

Water confined in nanoscale spaces is structurally different from bulk water, but for larger confinements (>8 Angstroms), it's mainly the surfaces influencing the structure, not the confinement itself. Only at extremely small confinements (<8 Angstroms, about two water molecule layers thick) does the confinement start dictating the water's behavior, weakening its hydrogen bonds and forcing it to lie flat.

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Physical and Theoretical Chemistry Aug 11, 04:21 AM

Machine intelligence for chemical reaction space

Machine intelligence is transforming chemical reaction space exploration through data-driven approaches for predicting reaction outcomes, planning syntheses, optimizing reaction performance, designing catalysts, and classifying reactions. These technologies are accelerating discovery and development in both academia and industry, enabling more efficient and sustainable chemical processes.

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Physical and Theoretical Chemistry Jul 14, 05:11 PM

Unusual solute segregation phenomenon in coherent twin boundaries

This study reveals an unusual segregation phenomenon where larger solute atoms (Bi) preferentially occupy compression sites in {10-11} coherent twin boundaries of Mg alloys, contrary to the traditional strain minimization theory. First-principles calculations and experimental observations suggest that chemical bonding, rather than elastic strain, plays a dominant role in this unexpected segregation behavior.

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Physical and Theoretical Chemistry Jul 14, 06:53 AM

Microbial lag phase can be indicative of, or independent from, cellular stress

Microbial lag phase, often used as a stress indicator, isn't always correlated with stress levels or subsequent growth rates. While a relationship sometimes exists between lag time and germination/growth under stress, it's highly dependent on the microbe, stressor, and experimental conditions, suggesting lag phase is an unreliable stress measure.

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Physical and Theoretical Chemistry Jul 14, 06:53 AM

The evolution of critical thermal limits of life on Earth

Thermal tolerance limits, essential for species' survival, are shaped by contemporary climate conditions, deep-time climate legacies, and evolutionary constraints. Cold tolerance evolves faster than heat tolerance, suggesting limited adaptive potential to cope with rapidly rising temperatures, particularly for tropical ectotherms.

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Physical and Theoretical Chemistry Jul 14, 06:52 AM

Clarifying the quantum mechanical origin of the covalent chemical bond

This study challenges the traditional view that covalent bond formation is universally driven by the lowering of electron kinetic energy. The research suggests that this is not always the case, and other factors such as constructive quantum interference play significant roles. The results are supported by advanced computational modeling.

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Physical and Theoretical Chemistry Jul 14, 06:52 AM