12 research outputs found
Ultralow surface energy self-assembled monolayers of iodo-perfluorinated alkanes on silica driven by halogen bonding
No full textShou K, Hong JK, Wood ES, et al. Ultralow surface energy self-assembled monolayers of iodo-perfluorinated alkanes on silica driven by halogen bonding. Nanoscale. 2019;11(5):2401-2411
3D interconnect technology based on low temperature copper nanoparticle sintering
No full textWe explore a methodology for patterned copper nanoparticle paste for 3D interconnect applications in wafer to wafer (W2W) bonding. A novel fine pitch thermal compression bonding process (sintering) with coated copper nanoparticle paste was developed. Most of the particle size is between 10-30 nm. Lithographically defined stencil printing using photoresist and lift-off was used to apply and pattern the paste. Variations in sintering process parameters, such as: pressure, geometry and ambient atmosphere, were studied. Compared to Sn-Ag-Cu (SAC) microsolder bumps, we achieved better interconnect resistivity after sintering at 260 °C for 10 min, in a 700 mBar hydrogen forming gas (H2/N2) environment. The electrical resistivity was 7.84 ± 1.45 μΩ·cm, which is about 4.6 times that of bulk copper. In addition, metallic nanoparticle interconnect porosity can influence the electrical properties of the interconnect. Consequently, we investigated the porosity effect on conductivity using finite element simulation. A linear relationship between the equivalent conductivity and particle overlapping ratio was found.Accepted Author ManuscriptElectronic Components, Technology and MaterialsEKL Processin
Homology modeling of a Class A GPCR in the inactive conformation: A quantitative analysis of the correlation between model/template sequence identity and model accuracy
No full textPublished in final edited form as: J Mol Graph Model. 2016 November ; 70: 140–152. doi:10.1016/j.jmgm.2016.10.004.With the present work we quantitatively studied the modellability of the inactive state of Class A G protein-coupled receptors (GPCRs). Specifically, we constructed models of one of the Class A GPCRs for which structures solved in the inactive state are available, namely the β2 AR, using as templates each of the other class members for which structures solved in the inactive state are also available. Our results showed a detectable linear correlation between model accuracy and model/template sequence identity. This suggests that the likely accuracy of the homology models that can be built for a given receptor can be generally forecasted on the basis of the available templates. We also probed whether sequence alignments that allow for the presence of gaps within the transmembrane domains to account for structural irregularities afford better models than the classical alignment procedures that do not allow for the presence of gaps within such domains. As our results indicated, although the overall differences are very subtle, the inclusion of internal gaps within the transmembrane domains has a noticeable a beneficial effect on the local structural accuracy of the domain in question
Chain Collapse and Interfacial Slip of Polystyrene Films in Good/Nonsolvent Vapor Mixtures
No full textWe investigated the dynamics and
morphology of dewetting of metastable
polystyrene films (thickness 75–500 nm) cast on silicon substrates,
upon exposure to vapors of a mixture of toluene, a good solvent, and
ethanol, a nonsolvent. Adding more than 2 wt % ethanol to the saturated
toluene environment resulted in a dramatic increase in dewetting rate,
an increase in the contact angle of polymer droplets and hole rims
on the substrate, and extensive fingering leading to droplet shedding.
Films preannealed close to <i>T</i><sub>g</sub> before exposure
to the solvent vapors showed markedly slower dewetting. We conclude
that in the presence of a good/nonsolvent mixture the polymer chains
transition to a globule conformation, which leads to larger interfacial
slip, lower viscosity, and significant elastic stress. The slip length
derived in the presence of ethanol vapor is close to the values obtained
for polystyrene on hydrophobized silicon. As the dewetting process
is so significantly boosted by exposure to mixed toluene/ethanol vapors,
polystyrene films as thick as 520 nm could be dewetted
Role of cellular FKBP52 protein in intracellular trafficking of recombinant adeno-associated virus 2 vectors
No full textAbstractWe have reported that tyrosine-phosphorylated forms of a cellular protein, FKBP52, inhibit the second-strand DNA synthesis of adeno-associated virus 2 (AAV), leading to inefficient transgene expression from recombinant AAV vectors. To further explore the role of FKBP52 in AAV-mediated transduction, we established murine embryo fibroblasts (MEFs) cultures from FKBP52 wild-type (WT), heterozygous (HE), and knockout (KO) mice. Conventional AAV vectors failed to transduce WT MEFs efficiently, and the transduction efficiency was not significantly increased in HE or KO MEFs. AAV vectors failed to traffic efficiently to the nucleus in these cells. Treatment with hydroxyurea (HU) increased the transduction efficiency of conventional AAV vectors by ∼25-fold in WT MEFs, but only by ∼4-fold in KO MEFs. The use of self-complementary AAV (scAAV) vectors, which bypass the requirement of viral second-strand DNA synthesis, revealed that HU treatment increased the transduction efficiency ∼23-fold in WT MEFs, but only ∼4-fold in KO MEFs, indicating that the lack of HU treatment-mediated increase in KO MEFs was not due to failure of AAV to undergo viral second-strand DNA synthesis. Following HU treatment, ∼59% of AAV genomes were present in the nuclear fraction from WT MEFs, but only ∼28% in KO MEFs, indicating that the pathway by which HU treatment mediates nuclear transport of AAV was impaired in KO MEFs. When KO MEFs were stably transfected with an FKBP52 expression plasmid, HU treatment-mediated increase in the transduction efficiency was restored in these cells, which correlated directly with improved intracellular trafficking. Intact AAV particles were also shown to interact with FKBP52 as well as with dynein, a known cellular protein involved in AAV trafficking. These studies suggest that FKBP52, being a cellular chaperone protein, facilitates intracellular trafficking of AAV, which has implications in the optimal use of recombinant AAV vectors in human gene therapy
Improved transduction of primary murine hepatocytes by recombinant adeno-associated virus 2 vectors in vivo
No full textEffect of red blood cell shape changes on haemoglobin interactions and dynamics : A neutron scattering study: Hb Interactions and Dynamics in RBCs
No full textBy using a combination of experimental neutron scattering techniques, it is possible to obtain a statistical perspective on red blood cell (RBC) shape in suspensions, and the inter-relationship with protein interactions and dynamics inside the confinement of the cell membrane. In this study, we examined the ultrastructure of RBC and protein-protein interactions of haemoglobin (Hb) in them using ultra-small-angle neutron scattering and small-angle neutron scattering (SANS). In addition, we used the neutron backscattering method to access Hb motion on the ns time scale and Å length scale. Quasi-elastic neutron scattering (QENS) experiments were performed to measure diffusive motion of Hb in RBCs and in an RBC lysate. By using QENS, we probed both internal Hb dynamics and global protein diffusion, on the accessible time scale and length scale by QENS. Shape changes of RBCs and variation of intracellular Hb concentration were induced by addition of the Na + -selective ionophore monensin and the K + -selective one, valinomycin. The experimental SANS and QENS results are discussed within the framework of crowded protein solutions, where free motion of Hb is obstructed by mutual interactions
Effect of red blood cell shape changes on haemoglobin interactions and dynamics: a neutron scattering study
No full textBy using a combination of experimental neutron scattering techniques, it is possible to obtain a statistical perspective on red blood cell (RBC) shape in suspensions, and the inter-relationship with protein interactions and dynamics inside the confinement of the cell membrane. In this study, we examined the ultrastructure of RBC and protein-protein interactions of haemoglobin (Hb) in them using ultra-small-angle neutron scattering and small-angle neutron scattering (SANS). In addition, we used the neutron backscattering method to access Hb motion on the ns time scale and angstrom length scale. Quasi-elastic neutron scattering (QENS) experiments were performed to measure diffusive motion of Hb in RBCs and in an RBC lysate. By using QENS, we probed both internal Hb dynamics and global protein diffusion, on the accessible time scale and length scale by QENS. Shape changes of RBCs and variation of intracellular Hb concentration were induced by addition of the Na+-selective ionophore monensin and the K+-selective one, valinomycin. The experimental SANS and QENS results are discussed within the framework of crowded protein solutions, where free motion of Hb is obstructed by mutual interactions
Functional in vitro diversity of an intrinsically disordered plant protein during freeze–thawing is encoded by its structural plasticity
No full textFunctional in vitro diversity of an intrinsically disordered plant protein during freeze–thawing is encoded by its structural plasticity
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