Sub 20 nm Short Channel Carbon Nanotube Transistors

Carbon nanotube field-effect transistors with sub 20 nm long channels and on/off current ratios of > 1000000 are demonstrated. Individual single-walled carbon nanotubes with diameters ranging from 0.7 nm to 1.1 nm grown from structured catalytic islands using chemical vapor deposition at 700 degree Celsius form the channels. Electron beam lithography and a combination of HSQ, calix[6]arene and PMMA e-beam resists were used to structure the short channels and source and drain regions. The nanotube transistors display on-currents in excess of 15 microA for drain-source biases of only 0.4 Volt.Comment: Nano Letters in pres

Low temperature structural phase transition and incommensurate lattice modulation in the spin gap compound BaCuSi2O6

Results of high resolution x-ray diffraction experiments are presented for single crystals of the spin gap compound BaCuSi$_2$O$_6$ in the temperature range from 16 to 300 K. The data show clear evidence of a transition from the room temperature tetragonal phase into an incommensurately modulated orthorhombic structure below $\sim$100 K. This lattice modulation is characterized by a resolution limited wave vector {\bf q}$_{IC}$=(0,$\sim$0.13,0) and its 2$^{nd}$ and 3$^{rd}$ harmonics. The phase transition is first order and exhibits considerable hysteresis. This observation implies that the spin Hamiltonian representing the system is more complex than originally thought.Comment: 4 pages, 4 figure

Immunohistological studies on neoplasms of female and male Onchocerca volvulus: filarial origin and absence of Wolbachia from tumor cells

Up to 5% of untreated female Onchocerca volvulus filariae develop potentially fatal pleomorphic neoplasms, whose incidence is increased following ivermectin treatment. We studied the occurrence of 8 filarial proteins and of Wolbachia endobacteria in the tumor cells. Onchocercomas from patients, untreated and treated with antibiotics and anthelminthics, were examined by immunohistology. Neoplasms were diagnosed in 112 of 3587 female and in 2 of 1570 male O. volvulus. The following proteins and other compounds of O. volvulus were expressed in the cells of the neoplasms: glutathione S-transferase 1, lysosomal aspartic protease, cAMP-dependent protein kinase, alpha-enolase, aspartate aminotransferase, ankyrin E1, tropomyosin, heat shock protein 60, transforming growth factor-beta, and prostaglandin E2. These findings prove the filarial origin of the neoplasms and confirm the pleomorphism of the tumor cells. Signs indicating malignancy of the neoplasms are described. Wolbachia were observed in the hypodermis, oocytes, and embryos of tumor-harbouring filariae using antibodies against Wolbachia surface protein, Wolbachia HtrA-type serine protease, and Wolbachia aspartate aminotransferase. In contrast, Wolbachia were not found in the cells of the neoplasms. Further, neoplasm-containing worms were not observed after more than 10 months after the start of sufficient treatment with doxycycline or doxycycline plus ivermectin

Bias Dependence and Electrical Breakdown of Small Diameter Single-Walled Carbon Nanotubes

The electronic breakdown and the bias dependence of the conductance have been investigated for a large number of catalytic chemical vapor deposition (CCVD) grown single-walled carbon nanotubes (SWCNTs) with very small diameters. The convenient fabrication of thousands of properly contacted SWCNTs was possible by growth on electrode structures and subsequent electroless palladium deposition. Almost all of the measured SWCNTs showed at least weak gate dependence at room temperature. Large differences in the conductance and breakdown behavior have been found for "normal" semiconducting SWCNTs and small band-gap semiconducting (SGS) SWCNTs.Comment: submitted to Journal of Applied Physic

Temporary ectropion therapy by adhesive taping: a case study

<p>Abstract</p> <p>Introduction</p> <p>Various surgical procedures are available to correct paralytic ectropion, which are applied in irreversible facial paresis. Problems occur when facial paresis has an unclear prognosis, since surgery of the lower eyelid is usually irreversible. We propose a simple method to correct temporary ectropion in facial palsy by applying an adhesive strip.</p> <p>Patients and methods</p> <p>Ten patients with peripheral facial paresis and paralytic ectropion were treated with an adhesive strip to correct paralytic ectropion. We used "Steri-Strips" (45 × 6.0 mm), which were taped on the carefully cleaned skin of the lower eyelid and of the adjacent zygomatic region until the prognosis of the paresis was clarified. In addition to the examiner's evaluation of the lower lacrimal point in the lacrimal lake, subjective improvement of the symptoms was assessed using a visual analogue scale (VAS, 1–10).</p> <p>Results</p> <p>9 patients reported a clear improvement of the symptoms after adhesive taping. There was a clear regression of tearing (VAS (median) = 8; 1 = no improvement, 10 = very good improvement), the cosmetic impairment of the adhesive tape was low (VAS (median) = 2.5; 1 = no impairment, 10 = severe impairment) and most of the patients found the use of the adhesive strip helpful. There was slight reddening of the skin in one case and well tolerated by the facial skin in the other cases.</p> <p>Conclusion</p> <p>The cause and location of facial nerve damage are decisive for the type of surgical therapy. In potentially reversible facial paresis, procedures should be used that are easily performed and above all reversible without complications. Until a reliable prognosis of the paresis can be made, adhesive taping is suited for the temporary treatment of paralytic ectropion. Adhesive taping is simple and can be performed by the patient.</p

The glutathione biosynthetic pathway of Plasmodium is essential for mosquito transmission

1Infection of red blood cells (RBC) subjects the malaria parasite to oxidative stress. Therefore, efficient antioxidant and redox systems are required to prevent damage by reactive oxygen species. Plasmodium spp. have thioredoxin and glutathione (GSH) systems that are thought to play a major role as antioxidants during blood stage infection. In this report, we analyzed a critical component of the GSH biosynthesis pathway using reverse genetics. Plasmodium berghei parasites lacking expression of gamma-glutamylcysteine synthetase (γ-GCS), the rate limiting enzyme in de novo synthesis of GSH, were generated through targeted gene disruption thus demonstrating, quite unexpectedly, that γ-GCS is not essential for blood stage development. Despite a significant reduction in GSH levels, blood stage forms of pbggcs− parasites showed only a defect in growth as compared to wild type. In contrast, a dramatic effect on development of the parasites in the mosquito was observed. Infection of mosquitoes with pbggcs− parasites resulted in reduced numbers of stunted oocysts that did not produce sporozoites. These results have important implications for the design of drugs aiming at interfering with the GSH redox-system in blood stages and demonstrate that de novo synthesis of GSH is pivotal for development of Plasmodium in the mosquito

Structural Evolution of CO2-Filled Pure Silica LTA Zeolite under High-Pressure High-Temperature Conditions

[EN] The crystal structure of CO2-filled pure-SiO2 LTA zeolite has been studied at high pressures and temperatures using synchrotron-based X-ray powder diffraction. Its structure consists of 13 CO2 guest molecules, 12 of them accommodated in the large alpha-cages and one in the beta-cages, giving a SiO2/CO2 stoichiometric ratio smaller than 2. The structure remains stable under pressure up to 20 GPa with a slight pressure-dependent rhombohedral distortion, indicating that pressure-induced amorphization is prevented by the insertion of guest species in this open framework. The ambient temperature lattice compressibility has been determined. In situ high-pressure resistive-heating experiments up to 750 K allow us to estimate the thermal expansivity at P approximate to 5 GPa. Our data confirm that the insertion of CO2 reverses the negative thermal expansion of the empty zeolite structure. No evidence of any chemical reaction was observed. The possibility of synthesizing a silicon carbonate at high temperatures and higher pressures is discussed in terms of the evolution of C-O and Si-O distances between molecular and framework atoms.The authors thank the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO), the Spanish Research Agency (AEI), and the European Fund for Regional Development (FEDER) under Grant Nos. MAT2016-75586-C4-1-P, MAT2015-71842-P, Severo Ochoa SEV-2012-0267, and No.MAT2015-71070-REDC (MALTA Consolider). D.S.-P. and J.R.-F. acknowledge MINECO for a Ramon y Cajal and a Juan de la Cierva contract, respectively. Portions of this work were performed at GeoSoilEnviroCARS (Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation - Earth Sciences (EAR-1128799) and Department of Energy- GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Use of the COMPRES-GSECARS gas loading system was supported by COMPRES under NSF Cooperative Agreement EAR 11-57758. CO2 gas was also loaded at Diamond Light Source. Authors thank synchrotron ALBA-CELLS for beamtime allocation at MSPD line. British Crown Owned Copyright 2017/AWE. Published with permission of the Controller of Her Britannic Majesty's Stationery Office.Santamaria-Perez, D.; Marqueño, T.; Macleod, S.; Ruiz-Fuertes, J.; Daisenberger, D.; Chulia-Jordan, R.; Errandonea, D.... (2017). Structural Evolution of CO2-Filled Pure Silica LTA Zeolite under High-Pressure High-Temperature Conditions. Chemistry of Materials. 29(10):4502-4510. https://doi.org/10.1021/acs.chemmater.7b01158S45024510291

Assembling Neurospheres: Dynamics of Neural Progenitor/Stem Cell Aggregation Probed Using an Optical Trap

Optical trapping (tweezing) has been used in conjunction with fluid flow technology to dissect the mechanics and spatio-temporal dynamics of how neural progenitor/stem cells (NSCs) adhere and aggregate. Hitherto unavailable information has been obtained on the most probable minimum time (∼5 s) and most probable minimum distance of approach (4–6 µm) required for irreversible adhesion of proximate cells to occur. Our experiments also allow us to study and quantify the spatial characteristics of filopodial- and membrane-mediated adhesion, and to probe the functional dynamics of NSCs to quantify a lower limit of the adhesive force by which NSCs aggregate (∼18 pN). Our findings, which we also validate by computational modeling, have important implications for the neurosphere assay: once aggregated, neurospheres cannot disassemble merely by being subjected to shaking or by thermal effects. Our findings provide quantitative affirmation to the notion that the neurosphere assay may not be a valid measure of clonality and “stemness”. Post-adhesion dynamics were also studied and oscillatory motion in filopodia-mediated adhesion was observed. Furthermore, we have also explored the effect of the removal of calcium ions: both filopodia-mediated as well as membrane-membrane adhesion were inhibited. On the other hand, F-actin disrupted the dynamics of such adhesion events such that filopodia-mediated adhesion was inhibited but not membrane-membrane adhesion