Double resonance spectroscopy reveals structure and dynamics near transition states.

A shared ambition of molecular spectroscopy and molecular dynamics is to establish the truths of chemical intuition on solid physical bedrock. Experimental characterization of the transition state was thought unattainable, but modern techniques have begun to achieve the incredible.

Probing the Electronic Manifold of MgCl with Millimeter-Wave Spectroscopy and Theory: (3)Σ and (4)Σ States.

The millimeter/submillimeter spectrum of magnesium chloride (MgCl) has been observed in two new electronic excited states, (3)Σ and (4)Σ, using direct absorption methods. The molecule was synthesized in a mixture of Cl, argon, and magnesium vapor. For the (3)Σ state, multiple rotational transitions were measured in the = 0 level for all six isotopologues (MgCl, MgCl, MgCl, MgCl, MgCl, and MgCl), as well as up to = 13 for MgCl.

FT-spectroscopy of the CO rare isotopologue and deperturbation analysis of the AΠ(v = 3) level.

Research on CO was carried out using two complementary Fourier-transform methods: (1) vacuum-ultraviolet absorption spectroscopy, with an accuracy ca. 0.03 cm on the DESIRS beamline (SOLEIL synchrotron) and (2) visible emission spectroscopy with an accuracy of about 0.

Smoking Modifies the Association Between Radon Exposure and Incident Ischemic Stroke: The REGARDS Study.

Background: Exposure to radon has been linked to lung cancer and other lung diseases. Although biologically plausible, research of residential radon exposure in relation to stroke risk is scarce.

Methods: Study participants were from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) cohort (n=30 239), which consisted of male and female non-Hispanic Black and White adults aged 45 and older.

Signatures of Reaction Mechanisms Encoded in the Vibrational Population Distribution of Small-Molecule Products: Photodissociation of -Triazine Using 266 nm Radiation.

We utilize rotationally resolved Chirped-Pulse Fourier Transform millimeter-wave spectroscopy to study photodissociation dynamics of 1,3,5-Triazine (-Triazine) to form 3 HCN molecules. The (VPD) of the photofragments contains mechanistic details of the reaction. This photodissociation is performed using 266 nm radiation transverse to a seeded supersonic jet.

Prevalence of neonicotinoid insecticides in paired private-well tap water and human urine samples in a region of intense agriculture overlying vulnerable aquifers in eastern Iowa.

A pilot study among farming households in eastern Iowa was conducted to assess human exposure to neonicotinoids (NEOs). The study was in a region with intense crop and livestock production and where groundwater is vulnerable to surface-applied contaminants. In addition to paired outdoor (hydrant) water and indoor (tap) water samples from private wells, urine samples were collected from 47 adult male pesticide applicators along with the completions of dietary and occupational surveys.

VUV-VIS FT spectroscopy of the rare CO isotopologue of carbon monoxide: Analysis of the AΠ(v = 1) multiply-perturbed level.

Ro-vibronic spectra of the CO carbon monoxide isotopologue were obtained with (i) emission spectroscopy in the visible region using a Bruker IFS 125HR spectrometer (University of Rzeszów) and (ii) vacuum-ultraviolet absorption spectroscopy using the wave-front-division spectrometer on the DESIRS beamline of the SOLEIL synchrotron. A deperturbation analysis of the CO AΠ(v = 1) level was conducted from 598 observed transitions from the BΣ - AΠ(0, 1), CΣ - AΠ(0, 1), AΠ - XΣ(1, 0), BΣ - XΣ(0, 0), CΣ - XΣ(0, 0), IΣ - XΣ(2, 0) bands and five further nominally forbidden bands. An effective Hamiltonian and term-value fitting analysis was implemented.

Diabatic Valence-Hole States in the C Molecule: "Putting Humpty Dumpty Together Again".

Despite the long history of spectroscopic studies of the C molecule, fundamental questions about its chemical bonding are still being hotly debated. The complex electronic structure of C is a consequence of its dense manifold of near-degenerate, low-lying electronic states. A global multi-state diabatic model is proposed here to disentangle the numerous configuration interactions that occur within four symmetry manifolds of excited states of C (Π, Π, Σ , and Σ ).

Theory of oil fouling for microfiltration and ultrafiltration membranes in produced water treatment.

Unlabelled: Due to the complexity of oil-in-water emulsions, the existing literature is still missing a mathematical tool that can describe membrane fouling in a fully quantitative manner on the basis of relevant fouling mechanisms.

Hypothesis: In this work, a quantitative model that successfully describes cake layer formation and pore blocking is presented. We propose that the degree of pore blocking is determined by the membrane contact angle and the resulting surface coverage, while the cake layer is described by a mass balance and a cake erosion flux.

Radon exposure and risk of cerebrovascular disease: a systematic review and meta-analysis in occupational and general population studies.

Although it is biologically plausible, findings relating radon exposure to the risk of cerebrovascular disease (CeVD) are inconsistent and inconclusive. To investigate whether radon exposure was associated with the risk of CeVD, we qualitatively and quantitatively summarized the literature on radon and CeVD in both occupational and general populations. A search of PubMed, Embase, Scopus, and Web of Science was performed for peer-reviewed articles published through March 2022.

Permeate Flux in Ultrafiltration Processes-Understandings and Misunderstandings.

Concentration polarization refers to the rapid emergence of concentration gradients at a membrane/solution interface resulting from selective transfer through the membrane. It is distinguishable from fouling in at least two ways: (1) the state of the molecules involved (in solution for concentration polarization, although no longer in solution for fouling); and (2) by the timescale, normally less than a minute for concentration polarization, although generally at least two or more orders of magnitude more for fouling. Thus the phenomenon of flux decline occurring over a timescale of tens of minutes should not be attributed to concentration polarization establishing itself.

Does protracted radon exposure play a role in the development of dementia?

Radon is a ubiquitous radioactive gas that decays into a series of solid radioactive decay products. Radon, and its decay products, enter the human body primarily through inhalation and can be delivered to various tissues including the brain through systemic circulation. It can also reach the brain by neuronal pathways via the olfactory system.

Long-range model of vibrational autoionization in core-nonpenetrating Rydberg states of NO.

In high orbital angular momentum (ℓ ≥ 3) Rydberg states, the centrifugal barrier hinders the close approach of the Rydberg electron to the ion-core. As a result, these core-nonpenetrating Rydberg states can be well described by a simplified model in which the Rydberg electron is only weakly perturbed by the long-range electric properties (i.e.

Photodissociation of dicarbon: How nature breaks an unusual multiple bond.

The dicarbon molecule (C) is found in flames, comets, stars, and the diffuse interstellar medium. In comets, it is responsible for the green color of the coma, but it is not found in the tail. It has long been held to photodissociate in sunlight with a lifetime precluding observation in the tail, but the mechanism was not known.

Nonlinear rotational spectroscopy reveals many-body interactions in water molecules.

Because of their central importance in chemistry and biology, water molecules have been the subject of decades of intense spectroscopic investigations. Rotational spectroscopy of water vapor has yielded detailed information about the structure and dynamics of isolated water molecules, as well as water dimers and clusters. Nonlinear rotational spectroscopy in the terahertz regime has been developed recently to investigate the rotational dynamics of linear and symmetric-top molecules whose rotational energy levels are regularly spaced.

Telehealth Utilization Is Associated with Lower Risk of Discontinuation of Buprenorphine: a Retrospective Cohort Study of US Veterans.

Objective: Treatment for opioid use disorder (OUD) may include a combination of pharmacotherapies (such as buprenorphine) with counseling services if clinically indicated. Medication management or engagement with in-person counseling services may be hindered by logistical and financial barriers. Telehealth may provide an alternative mechanism for continued engagement.

Occurrence of neonicotinoids and sulfoxaflor in major aquifer groups in Iowa.

A statewide assessment of neonicotinoids in groundwater was conducted among a sample of public water supply wells in Iowa from October 2017 to August 2018. Samples from all the state's major aquifer groups were initially collected from 118 wells in 69 counties. Subsets of 55 untreated samples and 45 paired pre- and post-treatment samples were then collected in summer 2018, post-planting season for primarily corn and soybeans, to assess seasonal differences and the efficacy of treatment.

Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm.

The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations.

Preparation of high orbital angular momentum Rydberg states by optical-millimeter-wave STIRAP.

Rydberg states of molecules are intrinsically challenging to study due to the presence of fast non-radiative decay pathways, such as predissociation. However, selectively exciting Rydberg states with values of the orbital angular momentum (ℓ) ℓ ≳ 3 is a productive strategy to minimize this rapid decay and to populate molecular Rydberg states with lifetimes that approach those of atoms. In this proof-of-principle demonstration, we transfer population to an nf Rydberg state of the calcium atom by stimulated Raman adiabatic passage, in which an optical and a millimeter-wave field couple the initial and final states via an intermediate nd Rydberg state.

A critical review on the potential impacts of neonicotinoid insecticide use: current knowledge of environmental fate, toxicity, and implications for human health.

Neonicotinoid insecticides are widely used in both urban and agricultural settings around the world. Historically, neonicotinoid insecticides have been viewed as ideal replacements for more toxic compounds, like organophosphates, due in part to their perceived limited potential to affect the environment and human health. This critical review investigates the environmental fate and toxicity of neonicotinoids and their metabolites and the potential risks associated with exposure.

Photodissociation transition states characterized by chirped pulse millimeter wave spectroscopy.

The 193-nm photolysis of CHCHCN illustrates the capability of chirped-pulse Fourier transform millimeter-wave spectroscopy to characterize transition states. We investigate the HCN, HNC photofragments in highly excited vibrational states using both frequency and intensity information. Measured relative intensities of = 1-0 rotational transition lines yield vibrational-level population distributions (VPD).

The dicarbon bonding puzzle viewed with photoelectron imaging.

Bonding in the ground state of C[Formula: see text] is still a matter of controversy, as reasonable arguments may be made for a dicarbon bond order of [Formula: see text], [Formula: see text], or [Formula: see text]. Here we report on photoelectron spectra of the C[Formula: see text] anion, measured at a range of wavelengths using a high-resolution photoelectron imaging spectrometer, which reveal both the ground [Formula: see text] and first-excited [Formula: see text] electronic states. These measurements yield electron angular anisotropies that identify the character of two orbitals: the diffuse detachment orbital of the anion and the highest occupied molecular orbital of the neutral.

On the understanding and feasibility of "Breakthrough" Osmosis.

Osmosis is the movement of solvent across a permselective membrane induced by a solute-concentration gradient. Now in 'Forward Osmosis' it is empirically observed that the diffusion of the solute is counter to that of the solvent i.e.