Near-UV Extinction of Submicron Thickness Ice Films in the 290-350 nm Range at 258 K.

Ice clouds affect the energy balance of the atmosphere through absorption, reflection, and scattering of solar radiation. We have developed a new experimental technique to simultaneously measure thin ice film extinction and its thickness (about 0.06-0.

Ovariectomy induces hyperalgesia accompanied by upregulated estrogen receptor α and protein kinase B in the rat spinal cord.

Hormone supplementation is one of the common therapies for menopause-related disorders. Among different tools, the ovariectomy (OVX) rodents are widely accepted as an appropriate menopausal pain model. Our previous study has showed that OVX produces a significant pain facilitation in both acute pain and tonic pain, however, the underlying mechanisms remain unclear.

Toward Antifragility: Social Defeat Stress Enhances Learning and Memory in Young Mice Via Hippocampal Synaptosome Associated Protein 25.

Social adversity not only causes severe psychological diseases but also may improve people's ability to learn and grow. However, the beneficial effects of social adversity are often ignored. In this study, we investigated whether and how social adversity affects learning and memory in a mouse social defeat stress (SDS) model.

Gas-Phase Reactions of Deprotonated Nucleobases with H, N, and O Atoms.

Complex organic molecules, the hallmark of terrestrial life, are increasingly detected in exotic environments throughout the universe. Our studies probe the ion chemistry of these biomolecules. We report gas-phase reaction rate constants for five deprotonated nucleobases (adenine, cytosine, guanine, thymine, and uracil) reacting with the atomic species H, N, and O.

Elucidating the Reactivity of O (a Δ): A Study with Amino Acid Anions and Related Sulfur and Oxygen Anionic Species.

Rate constants and product ions were determined for a series of anions reacting with singlet molecular oxygen O (a Δ) at thermal energy using an electrospray ionization-selected ion flow tube. The 20 naturally occurring amino acids were used to produce corresponding deprotonated anions; only [Cys-H] and [Pro-H] were found to be reactive with O (a Δ), generating OSCHCH(NH)CO + HO and CHNO + HO, respectively. The reaction of O (a Δ) with [Cys-H] has a rate constant more than ten times larger than the reaction of O (a Δ) with [Pro-H].

The HNO radical anion: A proposed intermediate in diazeniumdiolate synthesis using nitric oxide and alkoxides.

The strategy of synthesizing diazeniumdiolates (X-N(O)=NO) through the coexistence of nitric oxide and alkoxides (RO) was introduced by Wilhelm Traube 120 years ago. Today, despite the wide use of diazeniumdiolate derivatives to release nitric oxide in the treatment of cancer, the first step of the reaction mechanism for diazeniumdiolate synthesis remains a mystery and is thought to be complex. We have studied the gas-phase reactions of nitric oxide with alkoxides at room temperature.

Reactivity of amino acid anions with nitrogen and oxygen atoms.

For many decades, astronomers have searched for biological molecules, including amino acids, in the interstellar medium; this endeavor is important for investigating the hypothesis of the origin of life from space. The space environment is complex and atomic species, such as nitrogen and oxygen atoms, are widely distributed. In this work, the reactions of eight typical deprotonated amino acids (glycine, alanine, cysteine, proline, aspartic acid, histidine, tyrosine, and tryptophan) with ground state nitrogen and oxygen atoms are studied by experiment and theory.

Reactions of Sulfur- and Oxygen-Containing Anions with Hydrogen Atoms: A Comparative Study.

Reactions of hydrogen atoms with small sulfur-containing anions, SCN, CHCOS, CHCOS, SCHCOOH, CHS, 2-HOOCCHS, and related oxygen-containing anions, OCN, CHCOO, CHCOO, HOCHCOO, CHO, 2-HOOCCHO, have been studied both experimentally and computationally. The experimental results show that associative electron detachment (AED) is the only channel for the reactions. The rate constants for reactions between sulfur-containing anions and H atoms are generally higher than for the related oxygen-containing anions with the exception of the reaction of SCN.

Involvement of NF-κB and the CX3CR1 Signaling Network in Mechanical Allodynia Induced by Tetanic Sciatic Stimulation.

Tetanic stimulation of the sciatic nerve (TSS) triggers long-term potentiation in the dorsal horn of the spinal cord and long-lasting pain hypersensitivity. CX3CL1-CX3CR1 signaling is an important pathway in neuronal-microglial activation. Nuclear factor κB (NF-κB) is a key signal transduction molecule that regulates neuroinflammation and neuropathic pain.

Experimental and Computational Studies of the Reactions of N and O Atoms with Small Heterocyclic Anions.

The existence of heterocyclic aromatic anions in extraterrestrial environments, such as the upper atmosphere of Titan, has been recently confirmed by data from the Cassini spacecraft. Nitrogen and oxygen atoms are also common species in the ionospheres of planets and moons and in the interstellar medium. In the current work, we extend previous studies to explore the reactivity of five-membered ring aromatic anions that contain nitrogen, oxygen, or sulfur (deprotonated pyrrole, furan, and thiophene) with N and O atoms both experimentally and computationally.

Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium.

The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally.

Experimental and Theoretical Studies of the Reactivity and Thermochemistry of Dicyanamide: N(CN)(2)(-).

Dicyanamide [N(CN)2(-)] is a common anionic component of ionic liquids, several of which have shown hypergolic reactivity upon mixing with white-fuming nitric acid. In this study, we explore the thermochemistry of dicyanamide and its reactivity with nitric acid and other molecules to gain insight into the initial stages of the hypergolic phenomenon. We have developed and utilized an electrospray ion source for our selected ion flow tube (SIFT) to generate the dicyanamide anion.

Computational studies of the gas phase reactions of ethers with anions: kinetic barriers, isotope effects, consecutive eliminations and site selectivity.

Bimolecular elimination reactions (E2) are fundamentally important processes in organic chemistry. Our current work focuses on a computational investigation of several interesting and unexpected experimental results previously obtained in our laboratory. In particular, we have examined the detailed mechanisms for generating CH(2)CHO(‒) from the reaction of HO(‒) + CH(3)CH(2)OCH(2)CH(2)OCH(3), the unusually large isotope effect (k(D)/k(H) = 5.

Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry.

Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications.

Deprotonated purine dissociation: experiments, computations, and astrobiological implications.

A central focus of astrobiology is the determination of abiotic formation routes to important biomolecules. The dissociation mechanisms of these molecules lend valuable insights into their synthesis pathways. Because of the detection of organic anions in the interstellar medium (ISM), it is imperative to study their role in these syntheses.

Gas-phase reactions of CF(+) with molecules of interstellar relevance.

We have studied the gas-phase reactions of CF(+) with 24 neutral species. Reaction rate constants and product branching fractions are measured at 298 K using a flowing afterglow-selected ion flow tube. Experimental work is supported by computational chemistry calculations to provide insight into the reactivity of classes of neutral molecules.

Anionic derivatives of uracil: fragmentation and reactivity.

Uracil is an essential biomolecule for terrestrial life, yet its prebiotic formation mechanisms have proven elusive for decades. Meteorites have been shown to contain uracil and the interstellar abundance of aromatic species and nitrogen-containing molecules is well established, providing support for uracil's presence in the interstellar medium (ISM). The ion chemistry of uracil may provide clues to its prebiotic synthesis and role in the origin of life.

Ovariectomy results in variable changes in nociception, mood and depression in adult female rats.

Decline in the ovarian hormones with menopause may influence somatosensory, cognitive, and affective processing. The present study investigated whether hormonal depletion alters the nociceptive, depressive-like and learning behaviors in experimental rats after ovariectomy (OVX), a common method to deplete animals of their gonadal hormones. OVX rats developed thermal hyperalgesia in proximal and distal tail that was established 2 weeks after OVX and lasted the 7 weeks of the experiment.

Up-regulation of interleukin-23 induces persistent allodynia via CX3CL1 and interleukin-18 signaling in the rat spinal cord after tetanic sciatic stimulation.

Tetanic stimulation of the sciatic nerve (TSS) induces sciatic nerve injury and long-lasting pain hypersensitivity in rats, and spinal glial activation and proinflammatory cytokines releases are involved. In the present study, we showed that spinal interleukin (IL)-23 and its receptor, IL-23R, are crucial for the development of mechanical allodynia after TSS. In the spinal dorsal horn, both IL-23 and IL-23R are expressed in astrocytes, and this expression is substantially increased after TSS.

Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C-H bond activation.

Both ceria (CeO2) and alumina (Al2O3) are very important catalyst support materials. Neutral binary oxide nanoclusters (NBONCs), CexAlyOz, are generated and detected in the gas phase and their reactivity with carbon monoxide (CO) and butane (C4H10) is studied. The very active species CeAlO4 (●) can react with CO and butane via O atom transfer (OAT) and H atom transfer (HAT), respectively.

[Involvement of peripheral NFκB in tetanic sciatic stimulation-induced neuropathic pain].

Tetanic stimulation of the sciatic nerve (TSS) induces long-term potentiation (LTP) of both C- and A-fiber-evoked field potentials in the spinal dorsal horn and long-lasting mechanical allodynia in rats. Though central mechanisms underlying those phenomena have been well studied, peripheral mechanisms still remain poorly known. Nuclear factor kappa B (NFκB) is an important transcription factor.

Thermal methane activation by a binary V-Nb transition-metal oxide cluster cation: a further example for the crucial role of oxygen-centered radicals.

The heteronuclear transition-metal oxide cluster activates methane: VNbO5(+) reacts with CH4 under ambient conditions via hydrogen-atom transfer (HAT), thus providing an interesting prototype example of room-temperature methane activation by a binary transition-metal oxide cluster.

Catalytic oxidation of CO by N2O conducted via the neutral oxide cluster couple VO2/VO3.

Neutral vanadium and cobalt oxide clusters are generated at the same time employing a V-Co mixed target. Experimental results indicate that the reaction VO2 + N2O → VO3 + N2 occurs in a fast flow reactor. This interpretation is further supported for a gas mixture of CO and N2O in the flow cell: regeneration of VO2 is observed for this case via the reaction VO3 + CO → VO2 + CO2.

Double C-H bond activation of hydrocarbons by a gas phase neutral oxide cluster: the importance of spin state.

The neutral cluster V2O5 is generated and detected in the gas phase. Its reactivity toward butane is studied both experimentally and theoretically. Experimental results show clearly that neutral V2O5 can react with n-butane (C4H10) to generate V2O5H2, indicating double hydrogen atom transfer from C4H10 to V2O5 to produce C4H8.