Nematic elastomers with aligned carbon nanotubes: new electromechanical actuators

We demonstrate, for the first time, the large electromechanical response in nematic liquid crystalline elastomers filled with a very low (~0.01%) concentration of carbon nanotubes, aligned along the nematic director at preparation. The nanotubes create a very large effective dielectric anisotropy of the composite. Their local field-induced torque is transmitted to the rubber-elastic network and is registered as the exerted uniaxial stress of order ~1kPa in response to a constant field of order ~1MV/m. We investigate the dependence of the effect on field strength, nanotube concentration and reproducibility under multiple field-on and -off cycles. The results indicate the potential of the nanotube-nematic elastomer composites as electrically driven actuators

The Texas construction sector: the tail that wagged the dog

The boom-to-bust days of the Texas construction industry will linger in people's memory for many years. D'Ann Petersen, Keith Phillips, and Mine Yucel examine the factors that led to the rise and fall of the Texas construction industry and determine the role the industry played in the state's volatile economy during the 1970s and 1980s. ; Petersen, Phillips, and Yucel employ an econometric model to analyze the roles residential and nonresidential construction played in the state's economic fluctuations from 1976 through 1990. The authors find that, although large swings in oil prices were the greatest source of economic instability in the Texas economy, the construction sector also played an important and independent role in the changing fortunes of the state. The authors' results show that the homebuilding sector, in particular, had a large impact on the Texas economy. In addition, the authors find that the state's economy needs several years to adjust to shocks in the construction industry. Consequently, the current expansion in residential construction is likely to have positive economic effects in the years ahead.Construction industry ; Texas

Modulating the catalytic activity of enzyme-like nanoparticles through their surface functionalization

The inclusion of transition metal catalysts into nanoparticle scaffolds permits the creation of catalytic nanosystems (nanozymes) able to imitate the behaviour of natural enzymes. Here we report the fabrication of a family of nanozymes comprised of bioorthogonal ruthenium catalysts inserted in the protective monolayer of gold nanoparticles. By introducing simple modifications to the functional groups at the surface of the nanozymes, we have demonstrated control over the kinetic mechanism of our system. Cationic nanozymes with hydrophobic surface functionalities tend to replicate the classical Michaelis Menten model, while those with polar groups display substrate inhibition behaviour, a key mechanism present in 20% of natural enzymes. The structural parameters described herein can be used for creating artificial nanosystems that mimic the complexity observed in cell machinery. © 2018 The Royal Society of Chemistry

Comparative Study of Influenza Virus Replication in MDCK Cells and in Primary Cells Derived from Adenoids and Airway Epithelium

Although clinical trials with human subjects are essential for determination of safety, infectivity, and immunogenicity, it is de- sirable to know in advance the infectiousness of potential candidate live attenuated influenza vaccine strains for human use. We compared the replication kinetics of wild-type and live attenuated influenza viruses, including H1N1, H3N2, H9N2, and B strains, in Madin-Darby canine kidney (MDCK) cells, primary epithelial cells derived from human adenoids, and human bron- chial epithelium (NHBE cells). Our data showed that despite the fact that all tissue culture models lack a functional adaptive im- mune system, differentiated cultures of human epithelium exhibited the greatest restriction for all H1N1, H3N2, and B vaccine viruses studied among three cell types tested and the best correlation with their levels of attenuation seen in clinical trials with humans. In contrast, the data obtained with MDCK cells were the least predictive of restricted viral replication of live attenuated vaccine viruses in humans. We were able to detect a statistically significant difference between the replication abilities of the U.S. (A/Ann Arbor/6/60) and Russian (A/Leningrad/134/17/57) cold-adapted vaccine donor strains in NHBE cultures. Since live at- tenuated pandemic influenza vaccines may potentially express a hemagglutinin and neuraminidase from a non-human influenza virus, we assessed which of the three cell cultures could be used to optimally evaluate the infectivity and cellular tropism of vi- ruses derived from different hosts. Among the three cell types tested, NHBE cultures most adequately reflected the infectivity and cellular tropism of influenza virus strains with different receptor specificities. NHBE cultures could be considered for use as a screening step for evaluating the restricted replication of influenza vaccine candidates

Evidence for a quantum-spin-Hall phase in graphene decorated with Bi_2Te_3 nanoparticles

Realization of the quantum spin Hall effect in graphene devices has remained an outstanding challenge dating back to the inception of the field of topological insulators. Graphene’s exceptionally weak spin-orbit coupling—stemming from carbon’s low mass—poses the primary obstacle. We experimentally and theoretically study artificially enhanced spin-orbit coupling in graphene via random decoration with dilute Bi_2Te_3 nanoparticles. Multiterminal resistance measurements suggest the presence of helical edge states characteristic of a quantum spin Hall phase; the magnetic field and temperature dependence of the resistance peaks, x-ray photoelectron spectra, scanning tunneling spectroscopy, and first-principles calculations further support this scenario. These observations highlight a pathway to spintronics and quantum information applications in graphene-based quantum spin Hall platforms

Evidence for a quantum-spin-Hall phase in graphene decorated with Bi2Te3 nanoparticles

Realization of the quantum-spin-Hall effect in graphene devices has remained an outstanding challenge dating back to the inception of the field of topological insulators. Graphene's exceptionally weak spin-orbit coupling -stemming from carbon's low mass- poses the primary obstacle. We experimentally and theoretically study artificially enhanced spin-orbit coupling in graphene via random decoration with dilute Bi2Te3 nanoparticles. Remarkably, multi-terminal resistance measurements suggest the presence of helical edge states characteristic of a quantum-spin-Hall phase; the magnetic-field and temperature dependence of the resistance peaks, X-ray photoelectron spectra, scanning tunneling spectroscopy, and first-principles calculations further support this scenario. These observations highlight a pathway to spintronics and quantum-information applications in graphene-based quantum-spin-Hall platforms

Universal Correlators from Geometry

Matrix model correlators show universal behaviour at short distances. We provide a derivation for these universal correlators by inserting probe branes in the underlying effective geometry. We generalize these results to study correlators of branes and their universal behaviour in the Calabi-Yau crystals, where we find a role for a generalized brane insertion.Comment: 25 pages, 2 figure

Carboxypeptidase 4 gene variants and early-onset intermediate-to-high risk prostate cancer

<p>Abstract</p> <p>Background</p> <p>Carboxypeptidase 4 <it>(CPA4) </it>is a zinc-dependent metallocarboxypeptidase on chromosome 7q32 in a region linked to prostate cancer aggressiveness. CPA4 is involved in the histone hyperacetylation pathway and may modulate the function of peptides that affect the growth and regulation of prostate epithelial cells. We examined the association between genetic variation in <it>CPA4 </it>and intermediate-to-high risk prostate cancer.</p> <p>Methods</p> <p>We studied 1012 men (506 cases and 506 controls) from Cleveland, Ohio. All cases had Gleason ≥ 7, clinical stage ≥ T2c, or PSA ≥ 10 ng/mL at diagnosis. Six <it>CPA4 </it>single-nucleotide polymorphisms were genotyped, and evaluated for their relation to prostate cancer. We also evaluated whether CPA4 variants influence risk of disease among men diagnosed at an earlier age (< 66 years).</p> <p>Results</p> <p>The nonsynonymous coding SNP (rs2171492, Cys303Gly) in <it>CPA4 </it>was associated with an increased risk of aggressive prostate cancer among younger patients (< 66 years). Specifically, men carrying the TT genotype had an approximately two-fold increased risk for being diagnosed with intermediate-to-high risk disease (Odds Ratio = 1.83, p = 0.04). In the overall population (all ages) none of the <it>CPA4 </it>SNPs demonstrated a statistically significant association with prostate cancer.</p> <p>Conclusion</p> <p>Coding variation in <it>CPA4 </it>may confer increased risk of intermediate-to-high risk prostate cancer among younger patients. Further work is needed to identify the functional aspects of this variation and understand its biological effects on prostate cancer. Such work may translate into more precise screening of higher risk individuals as well as guiding clinicians and patients toward earlier and more definitive treatment modalities in patients genetically identified as higher risk.</p

Prediction method of inhomogeneous thermal flux loss in a magnet

Thermal flux loss (FL) is one of the important properties in applications of Nd-Fe-B magnets to electrical and electronic devices. FL is expected to occur inhomogeneously in magnets with a complex shape, because it depends on the strength of the local demagnetizing field. Thus, in terms of their applications, we need to predict the inhomogeneous FL from basic magnetic properties measured for a magnet with a simple shape such as a sphere. In this contribution, we propose a method of predicting inhomogeneous initial flux loss, FLint, in a magnet with a complex shape, and compare the predicted values of FLint with the measured ones for a model magnet. Consequently, the predicted and measured distributions agreed with each other. This result suggests that the proposed method can be applied to the prediction of FLint in magnets with a complicated shape used in electrical and electronic devices. c2006 American Institute of Physic

Variable expression and silencing of CRISPR-Cas9 targeted transgenes identifies the AAVS1 locus as not an entirely safe harbour

Background: Diseases such as hypertrophic cardiomyopathy (HCM) can lead to severe outcomes including sudden death. The generation of human induced pluripotent stem cell (hiPSC) reporter lines can be useful for disease modelling and drug screening by providing physiologically relevant in vitro models of disease. The AAVS1 locus is cited as a safe harbour that is permissive for stable transgene expression, and hence is favoured for creating gene targeted reporter lines. Methods: We generated hiPSC reporters using a plasmid-based CRISPR/Cas9 nickase strategy. The first intron of PPP1R12C, the AAVS1 locus, was targeted with constructs expressing a genetically encoded calcium indicator (R-GECO1.0) or HOXA9-T2A-mScarlet reporter under the control of a pCAG or inducible pTRE promoter, respectively. Transgene expression was compared between clones before, during and/or after directed differentiation to mesodermal lineages. Results: Successful targeting to AAVS1 was confirmed by PCR and sequencing. Of 24 hiPSC clones targeted with pCAG-R-GECO1.0, only 20 expressed the transgene and in these, the percentage of positive cells ranged from 0% to 99.5%. Differentiation of a subset of clones produced cardiomyocytes, wherein the percentage of cells positive for R-GECO1.0 ranged from 2.1% to 93.1%. In the highest expressing R-GECO1.0 clones, transgene silencing occurred during cardiomyocyte differentiation causing a decrease in expression from 98.93% to 1.3%. In HOXA9-T2A-mScarlet hiPSC reporter lines directed towards mesoderm lineages, doxycycline induced a peak in transgene expression after two days but this reduced by up to ten-thousand-fold over the next 8-10 days. Nevertheless, for R-GECO1.0 lines differentiated into cardiomyocytes, transgene expression was rescued by continuous puromycin drug selection, which allowed the Ca 2+ responses associated with HCM to be investigated in vitro using single cell analysis. Conclusions: Targeted knock-ins to AAVS1 can be used to create reporter lines but variability between clones and transgene silencing requires careful attention by researchers seeking robust reporter gene expression