Distribution of Sulfides and Thiophenic Compounds in VGO Subfractions: Characterized by Positive-Ion Electrospray Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Detailed elemental composition and distribution of sulfides and thiophenic compounds in four subfractions of Kazakhstan vacuum gas oil (VGO) were determined by positive ion electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The sulfides in VGO subfractions were selectively oxidized into sulfoxides using tetrabutylammonium periodate (TBAPI). The sulfur compounds in the oxidized VGO subfractions were reacted by methylation to form methylsulfonium salts and were then characterized. Elemental composition and distribution of sulfides and thiophenic compounds in the VGO subfractions were characterized by their double bond equivalents (DBE) values and carbon numbers before and after the oxidation reactions. The results showed that the S₁ class species with DBE values of 6 and greater are likely thiophenic compounds, while those with DBE values less than 6 are sulfides. As boiling point of VGO increased, the abundance of thiophenic compounds increased. DBE value and carbon number of the compounds also increased

Characterization of Middle-Temperature Gasification Coal Tar. Part 2: Neutral Fraction by Extrography Followed by Gas Chromatography–Mass Spectrometry and Electrospray Ionization Coupled with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

A commercial lignite gasification-derived middle-temperature coal tar (MTCT) was subjected to acid–base extraction to obtain acidic, basic, and neutral fractions. The neutral fraction was characterized by mass spectrometry (MS) for hydrocarbon-group-type analysis and further fractionated by extrography into six subfractions, which were characterized by gas chromatography–mass spectrometry (GC–MS). Saturate, aromatic, and resin fractions of the neutral fraction accounted for 16.4, 47.6, and 36.0 wt %, respectively. The GC–MS analysis showed that the first neutral subfraction (15.7 wt %) contained alkanes, alkenes, and cycloalkanes; the second subfraction (52.0 wt %) contained 1–6-ring aromatics; the third subfraction (4.6 wt %) contained neutral nitrogen compounds, such as indoles, carbazoles, and benzocarbazoles; the fourth subfraction (8.2 wt %) contained neutral polar compounds, such as C₈–C₂₈ alkyl nitriles and aliphatic and aromatic ketones, such as 4-, 5-, and 6-ketones and phenyl ketones, derived from a series of propiophenone to decanophenone; the fifth subfraction (14.9 wt %) contained 2-ketones and aromatic ketones, such as acetophenones, indanones, and acetonaphthones; and most of the sixth subfraction (1.3 wt %) cannot be eluted from GC. Electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze the third neutral subfraction, which was enriched with neutral nitrogen compounds. In addition to indoles, carbazoles, and benzocarbazoles, FT-ICR MS analysis showed that dibenzocarbazoles and tribenzocarbazoles with various carbon numbers were present in the third neutral subfraction

Age-dependent reduction in synapse number in 9-month-old PS1_V97L-Tg Mice.

<p>(<b>A–H</b>) Brain sections from the hippocampal CA3 region of PS1_V97L-Tg mice at different ages probed with an antibody to the presynaptic marker synaptophysin. Scale bar represents 20 µm. (<b>I, J</b>) Expression levels of synaptophysin in the hippocampus of PS1_V97L-Tg mice were significantly reduced compared with Non-Tg littermates tested by western blotting at 9 months (p<0.05, n = 3/group) and is indicated by an asterisk. (<b>K, L</b>) Representative electron microscope photographs taken from the neuropil region of the CA3 in 12-month-old Non-Tg and PS1_V97L-Tg mice. Synapses were identified by the presence of synaptic vesicles and postsynaptic densities, which are typically shown at high magnification and are indicated by arrows. (M) Comparison of synapse density between the PS1_V97L-Tg mice and Non-Tg littermates showed a significant difference (p<0.05, n = 6/group) and is indicated by an asterisk.</p

Impairment of synaptic plasticity in hippocampal slices from 6-month-old PS1_V97L-Tg mice.

<p>(<b>A</b>) Comparison of PPF in 6-month-old mice. The upper channel shows the typical fEPSP traces derived from paired stimuli with an interpulse interval of 20 ms. The bottom channel shows the PPF in PS1_V97L-Tg and Non-Tg mice. (<b>B</b>) Comparison of LTP in 6-month-old mice. The upper channel shows the typical fEPSP traces before (black) and 1 h after (grey) HFS delivery. The bottom channel shows the slopes of the fEPSPs during the 70 min study. The slopes recorded in the last 10 min were analyzed; * indicates a statistically significant difference at p<0.05 (n = 10/group). Note that artifacts are not shown.</p

Tau hyperphosphorylation and tangle formation in PS1_V97L-Tg mice.

<p>(<b>A–J</b>) Detailed graphs of the cortex and hippocampus that show the age-dependent intracellular accumulation of AT-8 staining. (K, L) High-magnification of cortex from 12-month-old PS1_V97L-Tg mice stained with Thioflavin-S, which indicates that intracellular hyperphosphorylated tau forms NFTs compared with its Non-Tg littermate. (M) A representative electron microscope photograph revealing the presence of tau filaments that formed an herringbone pattern (black arrows) in 12-month-old PS1_V97L-Tg mice. (<b>N, O</b>) Western blotting analysis of AT-8 expression in the cerebral cortex of 12-month-old PS1_V97L-Tg mice and Non-Tg littermates. An asterisk indicates significant difference between the two groups (p<0.05, n = 3/group). CTX, cerebral cortex. Scale bar represents 50 µm for (<b>A–L</b>).</p

Microglial activation in PS1_V97L-Tg mice.

<p>(<b>A–H</b>) Brain sections taken from the cerebral cortex and probed by an antibody to Iba-1, indicating activated microglial cells. (<b>I–P</b>) Brain sections taken from the hippocampal CA3 region probed by an antibody to Iba-1, indicating activated microglial cells. (<b>Q, R</b>) Iba-1 expression in the cerebral cortex of PS1_V97L-Tg mice and Non-Tg littermates at 9 months, tested by western blotting. An asterisk indicates significant difference between the two groups (p<0.05, n = 3/group). CTX, cerebral cortex; Hippo, hippocampus. Scale bar represents 50 µm.</p

Characterization of Middle-Temperature Gasification Coal Tar. Part 3: Molecular Composition of Acidic Compounds

Coal tar has been considered as a potential energy alternative because of dwindling supplies of petroleum. To determine if the coal tar could be refined and upgraded to produce clean transportation fuels, detailed investigation of its composition is necessary, particularly for identifying the acidic components that account for about one-quarter of the weight of the coal tar. A middle-temperature coal tar (MTCT) and its fractions were characterized by gas chromatography–mass spectrometry (GC–MS) and negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with different ion transmission modes for high- and low-mass ions. Analytical results of narrow distillation fractions from FT-ICR MS agreed reasonably well with those from GC–MS, although each technique has its own advantages and disadvantages. In this work, FT-ICR MS was demonstrated to be capable of characterizing small molecules of <100 Da using appropriate operation conditions, thus yielding mass distributions to compare to GC–MS results. A continuous distribution in double bond equivalent (DBE) and carbon number was observed with the distillates of increasing boiling point, while the composition of the distillation residue was much more complex than that of distillates. Acidic compounds containing 1–7 oxygen atoms were observed in the MTCT by FT-ICR MS, with O₁ and O₂ classes being dominant. Various phenolic compounds with 1–4 aromatic rings were identified on the basis of literature references, including some molecules having structures resembling known biomarkers in petroleum and coal

Memory dysfunction in 9-month-old PS1_V97L-Tg mice.

<p>(<b>A</b>) MWM escape latency during training at 6 months or (<b>B</b>) at 9 months. (<b>C</b>) Numbers of platform location crosses in the probe trials at 6 and 9 months. (<b>D</b>) Swimming speed on the first training day at 6 and 9 months. * indicates a significant difference at p<0.05 (n = 6/group).</p

Increases in the levels of Aβ42 and the ratio of Aβ42/Aβ40 in PS1_V97L-Tg mice at 9 months of age.

<p>(<b>A</b>) Aβ40 expression level. (<b>B</b>) Aβ42 expression levels. (<b>C</b>) The ratio of Aβ42/Aβ40. ELISA measurements are from the cortex and the hippocampus of 9-month-old mice. * denotes a significant difference at p<0.05 (n = 6/group).</p

Age-dependent accumulation of Aβ oligomers in the neurons of PS1_V97L-Tg mice.

<p>(<b>A, B, C</b>) Brain sections probed by antibody 4G8 reflect PS1_V97L-Tg mice exhibiting intracellular Aβ protein, without extracellular amyloid plaque. (<b>D</b>) Brain sections probed by antibody A11 reflecting PS1_V97L-Tg mice exhibiting intracellular Aβ oligomers. (<b>E–X</b>) Display showing the age-dependent accumulation of Aβ oligomers stained with A11. PS1_V97L-Tg is presented as V97L for short. CTX, cerebral cortex; CA3, hippocampal CA3 region. Note that (<b>J–N</b>) and (<b>T–X</b>) are higher magnifications of (<b>E–I</b>) and (<b>O–S</b>), respectively. Scale bar represents 100 µm.</p