Depolymerization and Demethylation of Kraft Lignin in Molten Salt Hydrate and Applications as an Antioxidant and Metal Ion Scavenger.

To improve the reactivity and enrich the functionality of lignin for valorization, kraft lignin was depolymerized and demethylated via cleaving aryl and alkyl ether bonds in acidic lithium bromide trihydrate (∼60% LiBr aqueous solution). It was found that the cleavage of the ether bonds followed the order of β-O-4 ether > aryl alkyl ether in phenylcoumaran > dialkyl ether in resinol > methoxyl (MeO). The depolymerization via β-O-4 cleavage occurred under mild conditions (e.

Laboratory Measured Emission Losses of Methyl Isothiocyanate at Pacific Northwest Soil Surface Fumigation Temperatures.

Temperature is a major environmental factor influencing land surface volatilization at the time of agricultural field fumigation. Cooler fumigation soil temperatures relevant to Pacific Northwest (PNW) application practices with metam sodium/potassium should result in appreciably reduced methyl isothiocyanate (MITC) emission rates, thus minimizing off target movement and bystander inhalation exposure. Herein, a series of laboratory controlled flow-through soil column assessments were performed evaluating MITC emissions over the range of cooler temperatures (2-13°C).

Pretreatment of forest residues of Douglas fir by wet explosion for enhanced enzymatic saccharification.

The logging and lumbering industry in the Pacific Northwest region generates huge amount of forest residues, offering an inexpensive raw material for biorefineries. Wet explosion (WEx) pretreatment was applied to the recalcitrant biomass to optimize process conditions including temperature (170-190 °C), time (10-30 min), and oxygen loading (0.5-7.

Conversion of C6 and C5 sugars in undetoxified wet exploded bagasse hydrolysates using Scheffersomyces (Pichia) stipitis CBS6054.

Sugarcane bagasse is a potential feedstock for cellulosic ethanol production, rich in both glucan and xylan. This stresses the importance of utilizing both C6 and C5 sugars for conversion into ethanol in order to improve the process economics. During processing of the hydrolysate degradation products such as acetate, 5-hydroxymethylfurfural (HMF) and furfural are formed, which are known to inhibit microbial growth at higher concentrations.

Borderline personality disorder features and risk for prescription opioid use disorders.

Although there is evidence for high comorbidity between borderline personality disorder (BPD) and substance use disorders, particularly alcohol use, more research is needed on the associations between BPD and prescription opioid use because of the increasing national problem of prescription opioid misuse. The purpose of the present study was to examine relationships between BPD features and prescription opioid use, risk for misuse, consequences, and dependence features, and to determine which aspects of BPD account for these associations. As predicted, BPD features were associated with greater quantity and frequency of opioid use, risk for pain medication misuse, consequences, and dependence features.

Confocal microscopy for modeling electron microbeam irradiation of skin.

For radiation exposures employing targeted sources such as particle microbeams, the deposition of energy and dose will depend on the spatial heterogeneity of the sample. Although cell structural variations are relatively minor for two-dimensional cell cultures, they can vary significantly for fully differentiated tissues. Employing high-resolution confocal microscopy, we have determined the spatial distribution, size, and shape of epidermal keratinocyte nuclei for the full-thickness EpiDerm™ skin model (MatTek, Ashland, VA).

Photodetachment of Isolated Bicarbonate Anion: Electron Binding Energy of HCO3(.).

We report the first direct photodetachment photoelectron spectroscopy of HCO3(-) in the gas phase under low-temperature conditions. The observed photoelectron spectra are complicated due to excitations of manifolds in both vibrational and electronic states. A long and single vibrational progression with a frequency of 530 ± 20 cm(-1) is partially resolved in the threshold of the T = 20 K, 266 nm spectrum.

Electron affinities and electronic structures of o-, m-, and p-hydroxyphenoxyl radicals: a combined low-temperature photoelectron spectroscopic and Ab initio calculation study.

Hydroxyl substituted phenoxides, o-, m-, p-HO(C(6)H(4))O(-), and the corresponding neutral radicals are important species; in particular, the p-isomer pair, i.e., p-HO(C(6)H(4))O(-) and p-HO(C(6)H(4))O*, is directly involved in the proton-coupled electron transfer in biological photosynthetic centers.

Stepwise hydration of the cyanide anion: a temperature-controlled photoelectron spectroscopy and ab initio computational study of CN-(H2O)n, n=2-5.

We report the study of microsolvated CN(-)(H(2)O)(n) (n=1-5) clusters in the gas phase using a combination of experimental and computational approaches. The hydrated cyanide clusters were produced by electrospray and their structural and energetic properties were probed using temperature-controlled photoelectron spectroscopy (PES) and ab initio electronic structure calculations. Comparison between the low temperature (LT,T=12 K) and the room-temperature (RT) spectra shows a 0.

Photoelectron imaging of doubly charged anions, (-)O2C(CH2)nCO2(-) (n = 2-8): observation of near 0 eV electrons due to secondary dissociative autodetachment.

The hallmark of multiply charged anions is the repulsive Coulomb barrier (RCB), which prevents low-energy electrons from being emitted in photodetachment experiments. However, using photoelectron imaging, we have observed persistent near 0 eV electrons during photodetachment of doubly charged dicarboxylate anions, (-)O(2)C(CH(2))(n)CO(2)(-) (D(n)(2-), n = 2-8). Here we show that these low-energy electron signals are well structured and are independent of the detachment photon fluxes or energies.

CO chemisorption on the surfaces of the golden cages.

We report a joint experimental and theoretical study of CO chemisorption on the golden cages. We find that the Au(17)(-) cage is highly robust and retains its cage structure in Au(17)(CO)(-). On the other hand, the Au(16)(-) cage is transformed to a structure similar to Au(17)(-) upon the adsorption of CO.

Evidence of significant covalent bonding in Au(CN)(2)(-).

The Au(CN)(2)(-) ion is the most stable Au compound known for centuries, yet a detailed understanding of its chemical bonding is still lacking. Here we report direct experimental evidence of significant covalent bonding character in the Au-C bonds in Au(CN)(2)(-) using photoelectron spectroscopy and comparisons with its lighter congeners, Ag(CN)(2)(-) and Cu(CN)(2)(-). Vibrational progressions in the Au-C stretching mode were observed for all detachment transitions for Au(CN)(2)(-), in contrast to the atomic-like transitions for Cu(CN)(2)(-), revealing the Au-C covalent bonding character.

Structural evolution, sequential oxidation, and chemical bonding in tritantalum oxide clusters: Ta(3)O(n)(-) and Ta(3)O(n) (n = 1-8).

We report a combined photoelectron spectroscopy (PES) and density functional theory (DFT) study on a series of tritantalum oxide clusters, Ta(3)O(n)(-). Well-resolved PES spectra are obtained for Ta(3)O(n)(-) (n = 1-8) at several detachment photon energies, yielding electronic structure information which is used for comparison with the DFT calculations. A trend of sequential oxidation is observed as a function of O content until Ta(3)O(8)(-), which is a stoichiometric cluster.

Probing the electronic stability of multiply charged anions: sulfonated pyrene tri- and tetraanions.

The strong intramolecular Coulomb repulsion in multiply charged anions (MCAs) creates a potential barrier that provides dynamic stability to MCAs and allows electronically metastable species to be observed. The 1-hydroxy-3,6,8-pyrene-trisulfonate {[Py(OH)(SO(3))(3)](3-) or HPTS(3-)} was recently observed as a long-lived metastable MCA with a large negative electron binding energy of -0.66 eV.

Au10-: isomerism and structure-dependent O2 reactivity.

Structure isomers of the Au(10)(-) cluster and their chemical reactivity with O(2) are studied using photoelectron spectroscopy under different experimental conditions. In addition to the global minimum triangular D(3h) structure, at least three low-lying isomers (X', X'', and X''') are observed distinctly using argon tagging and O(2) titration. The D(3h) structure has a very high electron affinity of 3.

Photoelectron spectroscopy of cold hydrated sulfate clusters, SO4(2-)(H2O)n (n = 4-7): temperature-dependent isomer populations.

Sulfate is an important inorganic anion and its interactions with water are essential to understand its chemistry in aqueous solution. Studies of sulfate with well-controlled solvent numbers provide molecular-level information about the solute-solvent interactions and critical data to test theoretical methods for weakly bounded species. Here we report a low-temperature photoelectron spectroscopy study of hydrated sulfate clusters SO(4)(2-)(H(2)O)(n) (n = 4-7) at 12 K and ab initio studies to understand the structures and dynamics of these unique solvated systems.

Probing the electronic and structural properties of the niobium trimer cluster and its mono- and dioxides: Nb3On- and Nb3On (n = 0-2).

We report a photoelectron spectroscopy and density functional theory (DFT) study on the electronic and structural properties of Nb(3)(-), Nb(3)O(-), Nb(3)O(2)(-), and the corresponding neutrals. Well-resolved photoelectron spectra are obtained for the anion clusters at different photon energies and are compared with DFT calculations to elucidate their structures and chemical bonding. We find that Nb(3)(-) possesses a C(2v) ((3)A(2)) structure, and Nb(3) is a scalene C(s) ((2)A'') triangle.

Structural transition of gold nanoclusters: from the golden cage to the golden pyramid.

How nanoclusters transform from one structural type to another as a function of size is a critical issue in cluster science. Here we report a study of the structural transition from the golden cage Au(16)(-) to the pyramidal Au(20)(-). We obtained distinct experimental evidence that the cage-to-pyramid crossover occurs at Au(18)(-), for which the cage and pyramidal isomers are nearly degenerate and coexist experimentally.

Experimental and theoretical investigation of three-dimensional nitrogen-doped aluminum clusters Al8N- and Al8N.

The structure and electronic properties of the Al(8)N(-) and Al(8)N clusters were investigated by combined photoelectron spectroscopy and ab initio studies. Congested photoelectron spectra were observed and experimental evidence was obtained for the presence of multiple isomers for Al(8)N(-). Global minimum searches revealed several structures for Al(8)N(-) with close energies.

Photoelectron imaging of multiply charged anions: Effects of intramolecular Coulomb repulsion and photoelectron kinetic energies on photoelectron angular distributions.

Multiply charged anions possess strong intramolecular Coulomb repulsion (ICR), which has been shown to dictate photoelectron angular distributions (PADs) using photoelectron imaging. Here we report the effects of photoelectron kinetic energies on the PADs of multiply charged anions. Photoelectron images on a series of dicarboxylate dianions, (-)O(2)C(CH(2))(n)CO(2) (-) (D(n) (2-), n=3-11) have been measured at two photon energies, 532 and 266 nm.

Tuning the electronic properties of the golden buckyball by endohedral doping: M@Au16(-) (M = Ag,Zn,In).

The golden Au(16)(-) cage is doped systematically with an external atom of different valence electrons: Ag, Zn, and In. The electronic and structural properties of the doped clusters, MAu(16)(-) (M = Ag,Zn,In), are investigated by photoelectron spectroscopy and theoretical calculations. It is observed that the characteristic spectral features of Au(16)(-), reflecting its near tetrahedral (T(d)) symmetry, are retained in the photoelectron spectra of MAu(16)(-), suggesting endohedral structures with little distortion from the parent Au(16)(-) cage for the doped clusters.

Drinking motives as mediators in the relation between personality disorder symptoms and alcohol use disorder.

Research shows high comorbidity between Cluster B Personality Disorders (PDs) and Alcohol Use Disorders (AUDs). Studies of personality traits and alcohol use have identified coping and enhancement drinking motives as mediators of the relation among impulsivity, negative affectivity or affectivity instability, and alcohol use. To the extent that certain PDs reflect extreme expression of these traits, drinking motives were hypothesized to mediate the relation between PD symptoms and presence/absence of an alcohol use disorder (AUD).

Imaging intramolecular coulomb repulsions in multiply charged anions.

The properties of multiply charged anions are dominated by intramolecular Coulomb repulsion (ICR). Using photoelectron imaging, we show the effect of ICR on photoelectron angular distributions for a series of dianions, -O2C(CH2)_{n}CO_{2};{-} (D_{n};{2-}). The observed photoemission band of D_{n};{2-} was due to a perpendicular transition from the charged end group.

Development of a low-temperature photoelectron spectroscopy instrument using an electrospray ion source and a cryogenically controlled ion trap.

The ability to control ion temperatures is critical for gas phase spectroscopy and has been a challenge in chemical physics. A low-temperature photoelectron spectroscopy instrument has been developed for the investigation of complex anions in the gas phase, including multiply charged anions, solvated species, and biological molecules. The new apparatus consists of an electrospray ionization source, a three dimensional (3D) Paul trap for ion accumulation and cooling, a time-of-flight mass spectrometer, and a magnetic-bottle photoelectron analyzer.

DOE program--developing a scientific basis for responses to low-dose exposures: impact on dose-response relationships.

The DOE Low Dose Radiation Research Program focuses on biological mechanisms involved in response to low doses of both low and high-LET radiation (< 0.1Gy). This research program represents a merging of new technologies with cutting edge biological techniques associated with genomics.