Experimental and Theoretical Investigation of Homogeneous Gaseous Reaction of CO₂(g) + <i>n</i>H₂O(g) + <i>n</i>NH₃(g) → Products (<i>n</i> = 1, 2)

Decreasing CO₂ emissions into the atmosphere is key for reducing global warming. To facilitate the CO₂ emission reduction efforts, our laboratory conducted experimental and theoretical investigations of the homogeneous gaseous reaction of CO₂(g) + <i>n</i>H₂O­(g) + <i>n</i>NH₃(g) → (NH₄)­HCO₃(s)/(NH₄)₂CO₃(s) (<i>n</i> = 1 and 2) using Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy and ab initio molecular orbital theory. Our FTIR-ATR experimental results indicate that (NH₄)₂CO₃(s) and (NH₄)­HCO₃(s) are formed as aerosol particulate matter when carbon dioxide reacts with ammonia and water in the gaseous phase at room temperature. Ab initio study of this chemical system suggested that the reaction may proceed through formation of NH₃·H₂O­(g), NH₃·CO₂(g), and CO₂·H₂O­(g) complexes. Subsequent complexes, NH₃·H₂O·CO₂ and (NH₃)₂·H₂O·CO₂, can be formed by adding gaseous reactants to the NH₃·H₂O­(g), NH₃·CO₂(g), and CO₂·H₂O­(g) complexes, respectively. The NH₃·H₂O·CO₂ and (NH₃)₂·H₂O·CO₂ complexes can then be rearranged to produce (NH₄)­HCO₃ and (NH₄)₂CO₃ as final products via a transition state, and the NH₃ molecule acts as a medium accepting and donating hydrogen atoms in the rearrangement process. Our computational results also reveal that the presence of an additional water molecule can reduce the activation energy of the rearrangement process. The high activation energy predicted in the present work suggests that the reaction is kinetically not favored, and our experimental observation of (NH₄)­HCO₃(s) and (NH₄)₂CO₃(s) may be attributed to the high concentrations of reactants increasing the reaction rate of the title reactions in the reactor

Highly Oriented Thin Membrane Fabrication with Hierarchically Porous Zeolite Seed

Nanosized zeolite is widely used as seed for high quality zeolite membranes fabrication, while its complicated synthesis routine limits large-scale productions. In this work, a non-nanosized cubic hierarchically porous TS-1 zeolite (HTS-1), obtained by basic hydrothermal treatment of conventional ellipsoid solid TS-1, is used as seed to prepare highly oriented thin membranes. A capillary condensation phenomenon resulting from the unique hierarchically porous structure benefits gel attachment. Moreover, abundant ledges, kinks, and terraces on the HTS-1 surface promote epitaxial growth of the membrane. In contrast, the solid TS-1 seed induces intergrowth dominantly, which results in a thick TS-1 membrane. The HTS-1 membrane demonstrates superior CO₂/N₂ separation properties compared to the TS-1 one. It associates with thin oriented membrane morphology, leading to exposure of a high Miller index surface and less diffuse distance and tortuosity. The results suggest beneficial effects of a hierarchically porous TS-1 zeolite seed on the interfacial crystal growth for membrane fabrication. A similar conclusion is applicable to the case of a hierarchically porous zeolite β. This work develops a facile approach to obtain a highly oriented thin zeolite membrane with enhanced separation properties

Liquid Hydrocarbon Fuels from Catalytic Cracking of Waste Cooking Oils Using Basic Mesoporous Molecular Sieves K₂O/Ba-MCM-41 as Catalysts

Mesoporous molecular sieves K₂O/Ba-MCM-41, which feature base sites, were prepared under hydrothermal conditions. The structure, base properties, and catalytic activity of the mesoporous molecular sieves as heterogeneous catalysts for the cracking of waste cooking oil (WCO) were then studied in detail. K₂O/Ba-MCM-41 exhibited higher catalytic performance for the cracking of WCO than traditional base catalysts such as Na₂CO₃ and K₂CO₃. Moreover, the cracking of WCO generates fuels (main composition is C₁₂∼C₁₇ alkane or olefin) that have similar chemical compositions to diesel-based fuels, and K₂O/Ba-MCM-41 is of excellent stability. The catalyst could be recycled and reused with negligible loss in activity for four cycles. K₂O/Ba-MCM-41 is an environmentally benign heterogeneous basic catalyst for the production of liquid hydrocarbon fuels from low quality feed stocks

Primers used for potential mutations amplification.

<p>Primers used for potential mutations amplification.</p

Fundus photography of the proband and a normal subject.

<p>(A) Attenuation of retinal arterioles, bone-spicule pigmentation in the midperiphery, atrophy of the retinal pigment epithelium, waxy-pale discs, and enlarged optic cups in the fundus of the proband (B) Normal fundus.</p

Multiple sequence alignment of <i>SNRNP200</i>.

<p>Sequence alignment of hBrr2 from eight species is shown. Q885E occurs at a highly conserved position in hBrr2 (arrow).</p

The <i>SNRNP200</i> sequencing results.

<p>(Top) Sequencing data shows that a C to G transversion (arrow) resulted in the substitution of glutamine-885 by glutamic acid (Q885E) in affected individuals. (Bottom) The corresponding normal sequence (arrow) was found in unaffected family members and controls.</p

Clinical features of patients with the <i>SNRNP200</i> mutation.

<p>F: female; M: male; BCVA: best corrected visual acuity; logMAR: logarithm of the Minimum Angle of Resolution; NL: no light perception; IOP: intraocular pressure; PSC: posterior subcapsular cataract; ERG: electroretinography; NR: not recordable; Int: intensive Diff: diffuse; NA: not available.</p

Structure modeling of hBrr2(477–1174).

<p>(A) Orthogonal ribbon plots of the model of hBrr2(477–1174). Three conserved residues (Q885, S1087 and R1090) that may interact with RNA base are shown as space-filling spheres, and colored as wheat, red and yellow respectively. (B) Orthogonal ribbon plots of the Hel308 DNA helicase <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045464#pone.0045464-Berson1" target="_blank">[2]</a> (PDB ID: 2p6r). Cyan, Hel308; pink, DNA. Three DNA interacting residues R388, T596 and W599 in Hel308 which correlate to Q885, S1087 and R1090 in human respectively are shown as space-filling spheres, and colored in order as wheat, red and yellow. (C) A close view of the central pore in the model, highlighting the three conserved residues (Q885, S1087 and R1090). (D) A close view of the path of DNA strand through the central pore, highlighting the three related residues (R388, T596 and W599) implicated in DNA binding.</p