Comprehensive Proteomic Analysis of Spider Dragline Silk from Black Widows: A Recipe to Build Synthetic Silk Fibers

The outstanding material properties of spider dragline silk fibers have been attributed to two spidroins, major ampullate spidroins 1 and 2 (MaSp1 and MaSp2). Although dragline silk fibers have been treated with different chemical solvents to elucidate the relationship between protein structure and fiber mechanics, there has not been a comprehensive proteomic analysis of the major ampullate (MA) gland, its spinning dope, and dragline silk using a wide range of chaotropic agents, inorganic salts, and fluorinated alcohols to elucidate their complete molecular constituents. In these studies, we perform in-solution tryptic digestions of solubilized MA glands, spinning dope and dragline silk fibers using five different solvents, followed by nano liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis with an Orbitrap Fusion™ Tribrid™. To improve protein identification, we employed three different tryptic peptide fragmentation modes, which included collision-induced dissociation (CID), electron transfer dissociation (ETD), and high energy collision dissociation (HCD) to discover proteins involved in the silk assembly pathway and silk fiber. In addition to MaSp1 and MaSp2, we confirmed the presence of a third spidroin, aciniform spidroin 1 (AcSp1), widely recognized as the major constituent of wrapping silk, as a product of dragline silk. Our findings also reveal that MA glands, spinning dope, and dragline silk contain at least seven common proteins: three members of the Cysteine-Rich Protein Family (CRP1, CRP2 and CRP4), cysteine-rich secretory protein 3 (CRISP3), fasciclin and two uncharacterized proteins. In summary, this study provides a proteomic blueprint to construct synthetic silk fibers that most closely mimic natural fibers.     

Metal acetylacetonate–amine and metal nitrate–amine complexes as low‐emission catalysts for rigid polyurethane foam preparation

Six metal–amine complexes, Cu(acac)₂(trien), Zn(acac)₂(en), Zn(acac)₂(trien), Cu(NO₃)₂(en)₂, Cu(NO₃)₂(trien), and Cu(NO₃)₂(tetraen), are synthesized from metal acetylacetonates [M(acac)₂, where M = Cu and Zn] or metal nitrate [M(NO₃)₂, where M = Cu] and aliphatic amines (en = ethylenediamine, trien = triethylenetetramine, and tetraen = tetraethylenepentamine). These metal–amine complexes can be used as catalysts in the preparation of rigid polyurethane (RPUR) foams. All metal–amine complexes emit very weak odor when compared with N,N‐dimethylcyclohexylamine (DMCHA), which is a commercial catalyst commonly used in the preparation of RPUR foams. DMCHA emits very strong amine odor that affects working environment in RPUR foam processing. Among all metal complexes, Cu(acac)₂(trien) has the highest catalytic activity. In comparison with DMCHA, Cu(acac)₂(trien) shows slightly higher catalytic activity in gelling reaction but lower catalytic activity in blowing reaction. RPUR foam prepared from Cu(acac)₂(trien) has lower density and compressive strength than that prepared from DMCHA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42332.     

Lignin‐based polyurethane doped with carbon nanotubes for sensor applications

Modified eucalyptus kraft lignin doped with multiwall carbon nanotubes (MWCNTs) was used as a macromonomer in step‐growth polymerization with tolylene 2,4‐diisocyanate terminated poly(propylene glycol) with the aim of producing a conductive copolymer for all‐solid‐state potentiometric chemical sensor applications. The crosslinked elastomeric polyurethane obtained was characterized by Fourier transform infrared attenuated total reflection spectroscopy, scanning electron microscopy, tunnelling electron microscopy and atomic force microscopy. Doping of lignin‐based polyurethane with MWCNTs produced a significant enhancement of its electrical conductivity without deterioration of thermal and viscoelastic properties. The polymer composite displayed a low percolation threshold at an MWCNT concentration of 0.18% (w/w), which was explained by the oriented distribution of MWCNTs along lignin clusters. All lignin‐based polyurethanes doped with MWCNTs at concentrations above the percolation threshold are suitable for sensor applications. Copyright © 2012 Society of Chemical Industry     

Career experiences of doctors of psychology.

Surveyed 184 graduates (mean age 37 yrs) of 9 PsyD programs to determine the professional activities in which they were engaged, satisfaction with careers and graduate training in professional psychology, and public acceptance of the PsyD degree and compared the results with similar data on PhD clinicians. Most Ss were primarily engaged in direct professional services in professional settings. They were generally satisfied with their careers in professional psychology and significantly more satisfied with the graduate training they had received than were clinical psychologists trained in traditional PhD programs. More Ss reported that the PsyD degree was an advantage rather than a disadvantage when competing for jobs with candidates who had other degrees. PsyD Ss were found to be active joiners of professional associations. 91% of PsyD Ss who applied for licensure or certification encountered no difficulty due to their degree. Almost no unfavorable attitudes toward the degree were perceived among clients, employers, or colleagues. It is concluded that fears about perception of the PsyD as a second-rate credential are unfounded. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molded Carbon–Carbon Composites Based on Microcomposite Technology

A one-step, cost-effective processing methodology based on compression molding of a mixture of graphite particles and short fibers, both coated with a soluble polyimide adhesive was developed. This technique shows a considerable potential in decreasing the complexity of the current carbon–carbon fabrication procedures. The new process eliminates additional infiltration and densification steps following the initial carbonization, which reduces the processing time from 5 weeks to 3–5 days and saves energy. The structure and properties of the new carbon–carbon composites were characterized using optical and electronic microscopy, thermal analysis, density and porosity measurements, and mechanical properties (hardness and flexural strength).The flexural strengths ranged from 20–45 MPa. The densities ranged from 1.9 to 2.2 g/cc (which is close to pure graphite) while the porosity was as low as 3%. The CTE was approximately ± 1 ppm/C (R.T. to 550C). The thermal stability of the carbonized and graphitized specimens when heated in flowing air up to 500C and flowing nitrogen up to 1000C showed no observable weight loss.There are numerous applications for these materials which include: optical mirrors, medical implants, thermal radiators and parts for rotating equipment, etc.A car piston was successfully molded using a mixture of polymer coated graphite powder, flakes and chopped fibers.     

Direct numerical simulation of turbulent channel flows using a stabilized finite element method

Direct numerical simulations (DNS) of incompressible turbulent channel flows at Re_τ = 180 and 395 (i.e., Reynolds number, based on the friction velocity and channel half-width) were performed using a stabilized finite element method (FEM). These simulations have been motivated by the fact that the use of stabilized finite element methods for DNS and LES is fairly recent and thus the question of how accurately these methods capture the wide range of scales in a turbulent flow remains open. To help address this question, we present converged results of turbulent channel flows under statistical equilibrium in terms of mean velocity, mean shear stresses, root mean square velocity fluctuations, autocorrelation coefficients, one-dimensional energy spectra and balances of the transport equation for turbulent kinetic energy. These results are consistent with previously published DNS results based on a pseudo-spectral method, thereby demonstrating the accuracy of the stabilized FEM for turbulence simulations.     

Copper Compatible Barium Titanate Thin Films for Embedded Passives

Barium titanate thin films have been prepared by chemical solution deposition on 18 m thick, industry standard copper foils in the absence of chemical barrier layers. The final embodiment exhibits randomly oriented BaTiO₃ grains with diameters between 0.1 and 0.3 m, and an equiaxed morphology. The average film thickness is 0.6 m and the microstructure is free from secondary or interfacial phases. The BaTiO₃ films are sintered in a high temperature reductive atmosphere such that copper oxidation is avoided. Subsequent lower-temperature, higher oxygen pressure anneals are used to minimize oxygen point defects. Permittivities of 2500 are observed at zero bias and room temperature, with permittivities greater than 3000 at the coercive field. Loss tangents under 1.5% are demonstrated at high fields. The BaTiO₃ phase exhibits pronounced ferroelectric switching and coercive field values near 10 kV/cm. Temperature dependent measurements indicate a ferroelectric transition near 100C with very diffuse character. Combining the approaches of the multilayer capacitor industry with traditional solution processed thin films has allowed pure barium titanate to be integrated with copper. The high sintering temperature—as compared to typical film processing—provides for large grained films and properties consistent with well-prepared ceramics. Integrating BaTiO₃ films on copper foil represents an important step towards high capacitance density embedded passive components and elimination of economic constraints imparted by traditional noble metallization.