Miracle-dz/UniFAR-FTUs huggingface dataset:
An extended Heisenberg model for conjugated hydrocarbons

An improved valence bond model, in the form of an extended Heisenberg model including next-nearest-neighbor transpositions and six-cyclic permutations, is developed to describe the low-lying “covalent” portion of the Hubbard model eigenspectrum (at half filling). The use of a cluster expansion including all diameter 1 and 2 subgraphs plus the diameter 3 six-membered ring allows the coefficients in the extended Heisenberg model to be determined from the results of accurate calculations of the Hubbard spectrum of benzene. The model is found to predict the lower energy states of two test molecules, styrene and naphthalene, rather accurately, and is thus expected to be generally applicable to benzenoid aromatic hydrocarbons.
Conduction gap in graphene strain junctions: direction dependence

It has been shown in a recent study (Nguyen et al 2014 Nanotechnology 25 165201) that unstrained/strained graphene junctions are promising candidates to improve the performance of graphene transistors which is usually hindered by the gapless nature of graphene. Although the energy bandgap of strained graphene still remains zero, the shift of Dirac points in the k-space due to strain-induced deformation of graphene lattice can lead to the appearance of a finite conduction gap of several hundred meV in strained junctions with a strain of only a few per cent. However, since it depends essentially on the magnitude of the Dirac point shift, this conduction gap strongly depends on the direction of applied strain and the transport direction. In this work, a systematic study of conduction-gap properties with respect to these quantities is presented and the results are carefully analyzed. Our study provides useful information for further investigations to exploit graphene-strained junctions in electronic applications and strain sensors.
Polyethyelene Glycols and Drug Release

AbstractThe dissolution rates of several drugs may be increased by incorporation into solid polyethylene glycols1. These dispersions are usually manufactured by heating a physical mixture of the drug and polymer to the fluid state and subsequently cooling to room temperature.The physical structure of both the drug and the polyethylene glycol will be discussed, as these factors may affect the rate of drug release from the dispersions2,3. The solid state properties of both components have traditionally been studied by X-ray diffraction and/or by differential scanning calorimetry (DSC). The latter technique has facilitated the use of phase diagrams in the investigation of the melting properties of the dispersions, these usually indicating the presence of eutectics, monotectics, solid solutions or glasses. The application of a further technique, dielectric spectroscopy, in the study of molten and solid dispersions will be described.The mechanisms by which drug dissolution rate may be enhanced will be describe.
Interfacial Rheological Properties of a Series of Bolaamphiphilic Poly(fluorooxetane)s

Interfacial rheological studies were performed on a series of bolaamphiphilic α,ω-(diammonium disulfato)poly(fluorooxetane)s of several perfluoroalkyl chain lengths. Similar measurements were performed on a small-molecule, anionic fluorosurfactant with a −C8F17 perfluoroalkyl group that is known to be an effective flow and leveling aid in aqueous coatings. Dilational viscoelasticities were measured for the fluorosurfactants as a function of concentration and oscillation rate. Elasticities were found to increase with increasing perfluoroalkyl chain length. All elasticities exhibited a strain rate dependence indicative of the influence of diffusional relaxation on elasticity values. Phase angles were found to be in the range for diffusional relaxation and decreased with increasing concentration and strain rate. Using interfacial rheological data, characteristic fluid dynamics numbers were calculated for the fluorosurfactants. Among these was the Marangoni number. Calculated Marangoni numbers for the poly(fl.
Disinfection by-products management in high quality recycled water

During the production of high quality recycled water (HQRW) by means of reverse osmosis (RO) membrane filtration, chloramines (used to avoid biofouling) can generate disinfection by-products (DBPs) which could ultimately end up in the product water. This paper compares the fate of DBPs and organic halogen content generated during the production of HQRW under two different disinfection strategies employed prior to RO filtration: (i) in line-formed chloramines with a short contact time between secondary effluent and disinfectant versus (ii) pre-formed chloramines with a long contact time between secondary effluent and disinfectant. In general, pre-formed chloramines formed less trihalomethanes (THMs) in comparison to in line-formed chloramines even after a longer contact time. However, pre-formed chloramines still generated iodo-THMs (I-THMs) which are of concern since they are suspected to be more toxic than their chlorinated and brominated analogues. I-THMs were very effectively reduced by the advanced oxidation process placed after the membrane process. Chloramines also form other halogenated by-products whose identity is unknown. In this study, more than 95% of total organic halogen formed by chloramines was rejected by the RO membranes although the reduction of targeted low molecular weight DBPs was only around 50%. Specific rejections for individual DBPs vary, ranging from low for haloacetonitriles and high for haloketones.
Molecular order and dynamics of liquid crystals formed from hydrogen-bonded networks of 5-octadecyloxyisophthalic acid

The supramolecular organization of 5-octadecyloxyisophthalic acid (C18ISA) and its complexes with different bases has been studied by polarization microscopy, differential scanning calorimetry (DSC), IR spectroscopy and X-ray diffraction (XRD). The molecular dynamics have been elucidated using solid-state 1H NMR and 2H NMR spectroscopy of C18ISA selectively deuteriated in the 2-, 4- and 6-positions of the aromatic ring. These systems form novel mesogenic structures. The stability of the liquid-crystalline phase depends on intermolecular interactions such as hydrogen and ionic bonding, as well as hydrophobic interactions due to the side-chain packing between the complementary components of the system. On cooling from the melt, C18ISA shows a monotropic liquid-crystalline phase with a non-interdigitated lamellar structure. Optical textures on hydrophobic substrates exhibit a highly fluid smectic phase. On heating, a new type of crystalline mesophase in the temperature range 385–433 K is observed that rests on the hydrophobic interactions of the alkyl chains, while the hydrogen-bonded layer breaks down at the phase transition at 386 K. Similar behaviour is observed for most of the C18ISA-4,4′-bipyridyl complexes. The C18ISA-piperazine complex forms a different enantiotropic liquid-crystalline phase with a broad mesophase range of 150 K. Solid-state 2H NMR spectroscopy proves the high molecular order of the complex, which can be macroscopically oriented in the magnetic field. IR spectral data of the complex indicate both ionic and hydrogen-bonding character. The conformational order of the alkyl chains is reduced at the phase transition into the liquid-crystalline phase so that for this complex the mesophase is stabilized by hydrogen and ionic bonds.
Systematic investigation of parameters affecting ozonation oxidation of emerging contaminants

The effect of five process variables‐pH, dissolved organic matter (DOM), ozone concentration, contact time, and temperature— on the removal efficiency of 14 selected pharmaceutically active compounds and bisphenol A was studied through fractional factorial‐ designed experiments. Results showed that DOM content and ozone dose had the most significant effect, accounting for 60–99% of the observed variability in oxidation efficiencies for compounds with both fast and slower reaction rates with ozone. Oxidation efficiency of > 90% is expected for the fast‐reacting compounds at ozone exposures > 1.3 mg/L × min, over the wide range of operating conditions used in the study. For compounds with a slower reaction rate with ozone, the oxidation efficiency is expected to be variable and strongly dependent on the characteristics of the raw water, particularly the concentration and nature of the DOM.
Label-free fluorescence turn-on detection of Pb2+ based on AIE-active quaternary ammonium salt of 9,10-distyrylanthracene

A label-free fluorescence turn-on approach for the selective sensing of Pb2+ based on quaternary ammonium salt of 9,10-distyrylanthracene with aggregation-induced emission (AIE) property was developed through Pb2+-induced allosteric G-quadruplex (G4). The method is simple, easy to operate, cost-effective, and provides good sensitivity and selectivity.
Raman spectroscopy of aqueous methanol solutions under pressure

Recently, Dixit et al. (2002) used neutron diffraction to probe the molecular-scale structure of a concentrated methanol–water mixture (7:3 molar ratio) under ambient conditions. Their results suggest that the anomalous thermodynamics of water–alcohol systems arises from incomplete mixing at the molecular level, i.e. most of the water molecules exist as small hydrogen-bonded strings and clusters in a fluid of close-packed methyl groups. The application of high hydrostatic pressure together with Raman spectroscopy is a powerful technique to detect such structural changes in associated systems. In this work, we present measurements of Raman spectra of water–methanol mixtures under pressure at room temperature. We have used an anvil cell device with sapphire anvils to generate pressures up to 10 kbar. Our results allow us to suggest important changes on the cluster distribution as a function of pressure.
Supervised-reinforcement learning for a mobile robot in a real-world environment

The students in the Center for Intelligent Systems (CIS) lab were especially helpful, and I offer my sincerest gratitude to them: Flo Fottrell deserves special thanks for all her support. Outside the CIS lab, I would like to thank Megan Rothney for being critical without being coarse and for being a genuine friend. Outside of Vanderbilt University, I owe recognition to Nate Koenig for help with the Player software and John Sweeney for help with the SICK laser. Finally, let it be known that I thank God for all areas of my life, which I received without cost and will give without cost. My parents have always been supportive of my decisions in life, and I cannot thank them enough! I also thank my siblings and extended family for their continued support as well. Lastly, to Aaron Welch, who has been my comfort on a daily basis throughout this scholastic effort, and I thank him for his unwavering encouragement.
(Bio)-synthesis of Au NPs from soy isoflavone extracts as a novel assessment tool of their antioxidant capacity

In this work, (bio)-synthesis of Au NPs using selected isoflavone classes has been studied. To this end, relevant aglycones (genistein and daidzein) and their glycosides (genistin and daidzin) as well as complex soy-extracts with a well-documented composition have been explored. A sigmoidal curve described the (bio)-synthesis of Au NPs which was used to evaluate the antioxidant activity and to carry out a reliable comparison of the antioxidant activity of soy isoflavone extracts towards the assessment of two relevant parameters: the concentration value at which the absorption reaches its half-value; X50c, and Au NPs production, KAuNPs. Although both isoflavone classes generated Au NPs; however, genistein exhibited a marked bio-synthesis efficiency with the lowest X50c = 70 mg L−1 and the highest KAuNPs = 0.200 mg−1 L values. In addition, complex soy isoflavone extracts with high total isoflavone aglycone content exhibited higher bio-synthesis efficiency than those found with high total glycoside content. Interestingly, excellent correlations between X50c and total phenolics (TP) (from Folin–Ciocalteu (FC) assay as truly antioxidant capacity assay) (r = 0.93, p-value < 0.05) and KAuNPs and TP (r = 0.85, p-value < 0.10) were also obtained confirming the superior antioxidant activity of aglycones isoflavone class. UV-vis and TEM characterization revealed that both genistein standard and soy isoflavone extracts with a high aglycone content produced red colloidal solutions of Au NPs. In contrast, glycoside standards as well as soy isoflavone extracts with a high glycoside content, generated blue colloidal solutions. The overall results obtained from our studies allowed us to hypothesize that the high antioxidant activity found in soy isoflavone extracts could have a significant direct relationship with the (bio)-synthesis of Au NPs with a small diameter and with the strong red colour exhibited at 540 nm. All of this opens new avenues in a very important research field such as the bio-synthesis of Au NPs as a novel tool for evaluation of antioxidant activity of target extracts.
Application of surface‐enhanced Raman scattering in cell analysis

In surface-enhanced Raman scattering (SERS), the scattered intensity is drastically increased due to a resonant interaction with surface plasmons of coin metals. SERS is a nondestructive spectroscopic method applied also to biomedical samples. It inherits the advantages of normal Raman spectroscopy and at the same time overcomes the inherent low sensitivity problem. These properties endow SERS with exciting opportunities to be a successful analytical tool for cell analysis. SERS can be used to detect only molecules located on or close to the metallic nanostructures which can support surface plasmon resonances for the enhancement of the Raman signals. Therefore, these metallic nanostructures play a key role in the application of SERS in cell analysis. By incorporating the SERS substrates into the biosamples, molecular structural probing and cellular imaging become possible. In the past decade, analysts worldwide have developed many schemes to study the chemical changes and component distribution in cells by using SERS. In this paper, the application of SERS in cell analysis is reviewed. Copyright © 2011 John Wiley & Sons, Ltd.
Comparison of the ultrafast absorption dynamics of eumelanin and pheomelanin

An enhanced photoreactivity of the red melanin, pheomelanin compared to the black melanin, eumelanin is commonly invoked to explain why fair-skinned individuals are more susceptible to skin cancers. Ultrafast pump−probe spectroscopy is used to examine the primary photodynamics of eumelanin from Sepia officinalis and synthetic pheomelanin following excitation at 303 nm. Both melanins reveal a transient absorption throughout the visible spectrum that rises within the instrument response. On the picosecond time scale, the transient absorption signal decays to a constant nonzero value, and the dynamics to nonexponential. Thus, both melanins do not exhibit complete ground-state recovery, suggestive of the formation of long-lived intermediates. Comparison to the initial transient absorption indicates the yield of such species is identical for the two pigments. The shape of the transient spectrum for the two melanins differ; however, global fits to the 13 different probe wavelengths used to construct each spectr.
Phase-induced porous composite microspheres sintered scaffold with protein–mineral interface for bone tissue engineering

Scaffolds for orthopedic reconstruction should best mimic the microenvironment of the bone to instil regenerative potential. In this study, a three-dimensional porous microsphere sintered scaffold that closely resembles bone micro-architecture has been fabricated. Synthesized nanohydroxyapatite (∼30–90 nm) using wet chemical precipitation and poly(hydroxybutyrate)/poly(e-caprolactone) were blended to develop composite porous microspheres via emulsion induced phase separation. Brunauer–Emmett–Teller analysis reveals presence of cylindrical mesopores in microspheres with surface area 10.64 m2 g−1, which on solvent/non-solvent sintering to scaffold, resembles trabecular section of rat sternum. The scaffold demonstrates desirable compressive strength (1.16 ± 0.17 MPa) and compressive modulus (6.8 ± 1.3 MPa) with slow degradation and microstructural stability for four weeks. Further, incorporation of bovine serum albumin (BSA) in the scaffold establishes protein–mineral interface and exhibits two-phase protein release mechanism (diffusion and polymer degradation). Pore interconnectivity and functional protein loading of scaffold have been evidenced by protein distribution analysis and secondary structural stability. The transverse section of MG63 cells cultured scaffolds with and without protein demonstrates cell infiltration and extension across the pores, while significantly higher proliferation is observed in protein scaffolds at day 7 (p < 0.05). Hence, the biomimetic scaffold with protein–mineral interface could be an ideal substitute for bone regeneration as it establish cell–matrix interaction.
Determination of Selective Quinones and Quinoid Radicals in Airborne Particulate Matter and Vehicular Exhaust Particles

Environmental Context.Fine and coarse airborne particulate matter (PM) has been linked to increases in respiratory diseases and lung cancer. PM contains a variety of compounds, such as metals, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, and quinones adsorbed in a carbonaceous polymeric matrix. Although quinones are found in small amounts in PM, they are capable of redox cycling and in the presence of oxygen catalyse the generation of reactive oxygen species (ROS) in biological systems. ROS are responsible for the induction of oxidative stress, especially oxidative damage to cellular proteins and DNA. This paper investigated quantitatively selected quinones and hydroquinones by high performance liquid chromatography in various airborne PM samples. Also, we investigated the presence of persistent semiquinone radicals in solid samples and quinoid radicals in aqueous extracts of alkaline solution by electron paramagnetic resonance spectroscopy. Abstract.In recent years, there has been an increasing interest in the study of the health effects of respirable particulate matter (PM) because of its deposition in the human lungs and adverse health effects. Analysis of PM content focused on substances of toxicological importance, such as polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, aliphatic hydrocarbons, alkyl-substituted benzenes and naphthalenes, transition metals and various quinones. Recent studies shifted their attention to quinones and their toxicological role in PM. Quinones can be transformed into their semiquinones, which undergo redox cycling and reduce oxygen to produce reactive oxygen species (ROS) in biological systems, resulting in the induction of oxidative stress, especially oxidative damage to cellular components and DNA. In the present study, the presence of five quinones, 1,2-benzenediol (catechol) and 1,4-benzenediol (hydroquinone) in various PM samples was identified and measured quantitatively by high performance liquid chromatography. Mean concentrations of individual target quinones ranged from 15–140 ng mg–1 in diesel and gasoline exhaust particles to 1.5–60 ng mg–1 (or 150–1100 pg m–3) in airborne PM (total suspended particulates, PM aerodynamic diameter 10 μm, PM aerodynamic diameter 2.1 μm) samples. Precision (repeatability and reproducibility) varied from 5 to 15%. Also, examples of electron paramagnetic resonance spectra for the single broad unstructured signal are presented, corresponding to the persistent stable semiquinone radicals of solid samples of PM, and the formation of quinoid radicals in aqueous extracts of PM samples in air-saturated carbonate-buffered solution, pH 9.5–10.
Field scale variability of nitrogen and δ15N in soil and plants

Abstract Understanding the factors that influence soil and plant nitrogen (N) spatial variability may improve our ability to develop management systems that maximize productivity and minimize environmental hazards. The objective of this study was to determine the field (65 ha) scale spatial variability of N and δ15N in soil and corn (Zea mays). Soil, grain, and stover samples were collected from grids that ranged in size from 30 by 30 m to 60 by 60 m. Plant samples, collected following physiological maturity in 1995, were analyzed for total N and δ15N. Soil samples, collected prior to planting in the spring of 1995 and 1996, were analyzed for inorganic‐N, total N, and δ15N. All parameters showed strong spatial relationships. In an undrained portion of the field containing somewhat poorly and poorly drained soils there was a net loss of 95 kg N ha‐1, while in an adjacent area that was tile drained there was a net gain of 98 kg N ha‐1. Denitrification and N mineralization most likely were responsible for lo.
Large-Scale Synthesis of the Anti-Cancer Marine Natural Product (+)-Discodermolide. Part 4: Preparation of Fragment C7-24

Coupling of C9-14 (4) and C15-21 (5a) fragments to produce the cis-trisubstituted olefin was achieved using Suzuki-type coupling conditions employed by Marshall (5a/tert-BuLi/B-OMe-9-BBN added to 4/Cs2CO3/Pd(dppf)2). The terminal (Z)-diene moiety was attached to aldehyde 10 by using a sequential Nozaki−Hiyama allylation and Peterson olefination sequence; careful monitoring of the disappearance of both diastereomeric β-hydroxysilanes was found to be essential for achieving a high yield. In the oxidation of alcohols 12 and 16 to 13 and 7, respectively, using iodobenzene diacetate and TEMPO, addition of a trace of water was found to be crucial for complete conversion. The C8-9 (Z)-olefin functionality was introduced on to aldehyde 13 using a Still−Gennari HWE reaction. Subsequent carbamate installation at C-19 followed by a reduction/oxidation sequence gave the title fragment C7-24 (7) ready to be coupled with the C1-6 fragment, which is described in Part 2 of this series.
Effects of Synthesis Conditions on Macroscopic and Microscopic Properties of Ordered Mesoporous Silica Fibers

Experiments were conducted to prepare ordered mesoporous silica fibers under different conditions (precursor type, temperature, acid concentration, and growth time). The ordered mesoporous silica fibers can be obtained with tetrabutyl orthosilicate as the silica source under the following conditions: temperature at 300 K; and tetrabutyl orthosilicate, cetyltrimethylammonium bromide, HCl, and water molar ratio of 1.0, 0.5, 10−98, and 2000. Synthesis at temperatures above 300 K resulted in ordered mesoporous silica of nonfibrous geometry (films or particles) due to a fast transfer rate of silica source material. A variation in acid concentration in the range of 2.0−6.4 vol % accelerates the formation of fibers with more pore microstructural ordering. Higher acid concentration leads to formation of irregular nonfibrous silica forms besides fibers due to rapid silica hydrolysis/condensation. Under controlled conditions the fibers' diameter becomes larger with a broader distribution for samples with longer gr.