The atomic resolution view of the nano-world

"The research I have done at UIC is using the Scanning Transmission Electron Microscope (STEM) to characterize the nano materials, such as the Mn promoted Co-based Fischer-Tropsch (FT) nano-catalyst on Ti support. The STEM makes it possible to observe the nano materials at atomic resolution, with the image contrast correlates with the material atomic number. The electron energy loss spectroscopy (EELS) combined with STEM could provide us the chemical information by mapping the elemental distribution of the nano-catalyst. All the information obtained by STEM is important for understanding the function of the Co-based FT catalyst, which could be a solution to the potential energy crisis. As can be seen in the image, a particle of 10 nm in diameter sits on a chunk of support. The later chemical analysis by EELS shows that it is a Co particle covered with a Mn shell sitting on the Ti support. One facet of the particle is hexagonal. The bright spots on the hexagonal facet are the atomic columns. The clear observation of the atomic columns demonstrates the powerful magnification function of the STEM. By using the STEM, the landscape of the nano-world is always amazing.

Ab Initio Study on Ultrafast Excited-State Decay of Allopurinol Keto-N9H Tautomer from Gas Phase to Aqueous Solution

The excited-state decay of the biologically relevant allopurinol keto-N9H tautomer populated at the optically bright S₁(¹<i>ππ</i>*) state in the gas phase and in aqueous solution has been explored theoretically. In solution, the hybrid quantum-mechanical/molecular-mechanical simulations were performed, where the QM region (keto-N9H) was treated at the ab initio SA-CASSCF level, while the MM region (water) was described by the TIP3P model. Here we find that there exist four parallel relaxation pathways in the gas phase, but only two of them occur in aqueous solution. In addition, an ultrafast S₁ → S₀ internal conversion is found in vacuum, with an estimated excited-state lifetime of 104.7 fs, much faster than that in water (242.8 fs), showing reasonable agreement with the available experimental finding in aqueous solution (τ < 200 fs). Calculations indicate that the presence of water solvent plays an important role in the excited-state dynamics of DNA base, showing the pronounced environmental effects on its decay pathways and excited-state lifetimes

Conversion of C5 Carbohydrates into Furfural Catalyzed by SO₃H‑Functionalized Ionic Liquid in Renewable γ‑Valerolactone

To obtain an efficient and green reaction system for the production of furfural (FF), this study investigated the use of a SO₃H-functionalized ionic liquid as a catalyst for the conversion of xylose in a solvent of renewable γ-valerolactone (GVL). A high FF yield of 78.12% was obtained in this reaction system catalyzed by 1-propylsulfonic-3-methylimidazolium chloride at 140 °C. The GVL remarkably enhanced the reaction rate and increased the xylose conversion and FF yield because the solvent effect of GVL could improve the catalytic activity of the acidic protons and suppress the side reactions. In addition, the ionic liquids showed satisfactory catalytic performance in the conversion of xylose to FF due to functionalization by introducing a SO₃H group. The conversion of other C5 carbohydrates (arabinose and xylan) was also tested in this system, and moderate FF yields were achieved

A Comprehensive Understanding of Enzymatic Catalysis by Hydroxynitrile Lyases with <i>S</i> Stereoselectivity from the α/β-Hydrolase Superfamily: Revised Role of the Active-Site Lysine and Kinetic Behavior of Substrate Delivery and Sequential Product Release

The highly homologous hydroxynitrile lyases from Manihot esculent (<i>Me</i>HNL) and Hevea brasiliensis (<i>Hb</i>HNL) both belong to the α/β-hydrolase superfamily, and they convert cyanohydrins into the corresponding ketone (aldehyde) and hydrocyanic acid, which is important for biosynthesis for carbon–carbon formation. On the basis of extensive MM and ab initio QM/MM MD simulations, one-dimensional and two-dimensional free energy profiles on the whole enzymatic catalysis by <i>Me</i>HNL have been explored, and the effects of key residues around the channel on the delivery of substrate and product have been discussed. The residue Trp128 plays an important gate-switching role to manipulate the substrate access to the active site and product release. In particular, the release of acetone and HCN has been first detected to follow a stepwise mechanism. The release of HCN is quite facile, while the escape of acetone experiences a barrier of ∼10 kcal/mol. The chemical reaction is an endergonic process with a free energy barrier of ∼17.1 kcal/mol, which dominates the entire enzymatic efficiency. Such energy costs can be compensated by the remarkable energy release during the initial substrate binding. Here the carbon–carbon cleavage is the rate-determining step, which differs from that of <i>Hb</i>HNL. The protonation state of Lys237 plays an important role in carbon–carbon bond cleavage by restoring the Ser80Ala mutant system to the wild system, which explains the discrepancy between <i>Me</i>HNL and <i>Hb</i>HNL at the molecular or atomic scale. The present results provide a basis for understanding the similarity and difference in the enzymatic catalysis by <i>Me</i>HNL and <i>Hb</i>HNL

Visualization 1.mp4

Visualization 1 shows the dynamic change of the PA vascular images during the process of the contact force changing from small to large and back again. The light source is fix, and the distance between the blood vessel and the light source remained almost unchanged during the imgaing. The probe pressed down on the ultrasound coupling pad placed on the skin

Changing the Reaction Pathway by NHC/Brønsted Base Cooperative Catalysis: Highly Stereoselective Synthesis of Multifunctional Benzo[<i>a</i>]fluoren-11-ones from the Dimerization of 2‑(Aroylvinyl)arylaldehydes

The unprecedented NHC/Brønsted base-cocatalyzed dimerization reaction of 2-(aroylvinyl)­arylaldehydes was reported. In the presence of a triazole carbene catalyst alone, no reaction of 2-(aroylvinyl)­arylaldehydes was observed. However, the combination of triazole carbene and 4-methoxyphenolate efficiently catalyzed the dimerization of 2-(aroylvinyl)­arylaldehydes to proceed through a benzoin–Michael–Michael reaction cascade, producing 6-aroyl-5-(aroylmethyl)-11a-hydroxybenzo­[<i>a</i>]­fluoren-11-ones as the sole diastereomers in good yields

Broadband Intelligent Programmable Metasurface with Polarization-Modulated Self-Adaptively Electromagnetic Functionality Switching

Programmable metasurfaces have received a great deal of attention due to their ability to dynamically manipulate electromagnetic (EM) waves. Despite the rapid growth, most of the existing metasurfaces require manual control to switch among different functionalities, which poses severe limitations on practical applications. Here, we put forth an intelligent metasurface that has self-adaptively EM functionality switching in broadband without human participation. It is equipped with polarization discrimination antennas (PDAs) and feedback components to automatically adjust functionalities for the different incident polarization information. The PDAs module can first perceive the polarization of incident EM waves, e.g., linear or circular polarization, and then provide the feedback signal to the controlling platform for switching the EM functionality. As exemplary demonstrations, a series of functionalities in 9-22 GHz bands have been realized, including beam scanning for x-polarization, specular reflection for y-polarization, diffuse scattering for left-handed circular polarization (LCP), and vortex beam generation for right-handed circular polarization (RCP) wave. Experiments verify the good self-adaptive reaction capability of the intelligent metasurface and are in good agreement with the designs. Our strategy provides an avenue toward future unmanned devices that are consistent with the ambient environment

Supplementary document for Automatic force-controlled 3D photoacoustic system for human peripheral vascular imaging - 6239647.pdf

System resolutio

Reversal potential of GABA responses (E_GABA) is more negative than the local RMP.

<p>A, Gramicidin perforated patch recording from an axon bleb. Arrow indicates the recorded bleb. Top, DIC image of the recording; middle, fluorescence image (unlabeled bleb); bottom, fluorescence image (labeled bleb, indicating rupture of patch membrane). Scale bar: 50 µm. B, Example traces showing GABA responses at different holding potentials (from –90 to –50 mV) before (black) and after the break-in (membrane rupture, gray). C, Comparison of E_GABA and RMP. Note that E_GABA at both the soma and the distal axon bleb were more hyperpolarized than their local RMP. *, P<0.05, paired t-test.</p

Additional file 1: of Doxycycline attenuates breast cancer related inflammation by decreasing plasma lysophosphatidate concentrations and inhibiting NF-ÎşB activation

Effects of doxycycline (Dox) on tumor growth, metastasis, and leukocyteinfiltration. (PPTX 2548 kb