Differential inhibition of postnatal brain,spinal cord and body growth by a growth hormone antagonist

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.     

Issues on nanoimprint lithography with a single-layer resist structure

We summarize our key developments in nanoimprint lithography (NIL) that employs a single layer resist lift-off process: lowering of the imprint temperature (for thermal imprint) and pressure, achieving uniform resist thickness and low residual resist layer thickness in the trenches, and eliminating metal ‘rabbit ears’ for the single-layer lift-off. In thermal NIL, our requirements for lower operating temperature and pressure motivated us to develop an alternative resist that is a viscous fluid at room temperature and cures at a lower temperature of 70 °C than the operating temperature of the conventional thermal NIL (≈200 °C). For UV NIL, we devised a method to dispense the resist onto a hydrophobic mold and use the hydrophilic substrate surface to spread the resist via surface wetting to engineer a continuous and uniform film. We also explored the use of Si(110) substrates as molds to produce features with perfectly vertical side walls, and the use of aqua regia to directly etch away rabbit ears. PACS 86.65.+h; 81.16.Nd; 81.16.Rf     

Transfer measurements for the Ti+Ni systems at near barrier energies

Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies. Coupled channel calculations incorporating couplings to 2⁺ and 3⁻ states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer were carried out for ^46,48Ti+⁶¹Ni systems. The present paper gives the results of these studies.     

Using FTIR spectroscopy to detect sericin on historic silk

Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide.Their optimum preservation demands an appreciation of their characteristics.One important concern,especially with regard to ancient Chinese silks,is whether the fabrics have been degummed.Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol.In previous research on aged silks,the presence of sericin has been inferred from amino acid analysis of hydrolysa...     

The link between nanoscale feature development in a negative resist and the Hansen solubility sphere

By systematically studying development of a high resolution, negative electron beam resist, hexa‐methyl acetoxy calix(6)arene, we have elicited a more general understanding of the underlying development mechanisms for negative resists. Using the three dimensional Hansen solubility parameters for more than 40 solvents, we have constructed a Hansen solubility sphere (HSS). From this sphere, we have estimated the Flory Huggins interaction parameter for solvents with hexa‐methyl acetoxy calix(6)arene and found a correlation between resist development contrast, nanoscale patterned feature quality, and the polymer‐solvent solubility. Conducting Atomic Force Microscopy (AFM) in a liquid cell, we have measured swelling for hexa‐methyl acetoxy calix(6)arene in four solvents. The swelling measurements indicate that the HSS gives an indication of the Flory‐Huggins interaction parameter. These measurements provide new insights into the development behavior of nanoscale features – necessary for obtaining the ultimate lithographic resolution. In addition, it demonstrates a methodology for choosing appropriate polymer‐solvent combinations for nanoscience applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2091–2105, 2009     

Iron-catalyzed Doyle-Kirmse reaction of allyl sulfides with (trimethylsilyl)diazomethane

[formula: see text] Iron salts efficiently catalyze the Doyle-Kirmse reaction of allyl sulfides with (trimethylsilyl)diazomethane and ethyl diazoacetate in dichloroethane at 83 degrees C. Competitive dimerization is less of a problem with (trimethylsilyl)diazomethane than with ethyl diazoacetate. Good results are obtained using only 1.5 equiv of (trimethylsilyl)diazomethane, even without slow addition. Phosphine ligands affect the kinetics, but not the diastereoselectivity. Dppe and BINAP lead to higher yields than dppp, but no enantioselection was detected with R-(+)-BINAP.     

One-kilobit cross-bar molecular memory circuits at 30-nm half-pitch fabricated by nanoimprint lithography

We have developed a process to fabricate a cross-bar structure using UV-curable nanoimprint lithography with a UV-curable double-layer spin-on resist, metal lift off and Langmuir–Blodgett film deposition. This process allowed us to produce 1-kbit cross-bar memory circuits at 30-nm half-pitch on both top and bottom electrodes. Read, write, erase and cross talking were also investigated. PACS 85.40.Hp; 81.07.-b; 81.16.Nd; 85.65.+h     

Interface segregating fluoralkyl-modified polymers for high-fidelity block copolymer nanoimprint lithography

Block copolymer (BCP) lithography is a powerful technique to write periodic arrays of nanoscale features into substrates at exceptionally high densities. In order to place these features at will on substrates, nanoimprint offers a deceptively clear path toward high throughput production: nanoimprint molds are reusable, promote graphoepitaxial alignment of BCP microdomains within their topography, and are efficiently aligned with respect to the substrate using interferometry. Unfortunately, when thin films of BCPs are subjected to thermal nanoimprint, there is an overwhelming degree of adhesion at the mold-polymer interface, which compromises the entire process. Here we report the synthesis of additives to mitigate adhesion based on either PS or PDMS with short, interface-active fluoroalkyl chains. When blended with PS-b-PDMS BCPs and subjected to a thermal nanoimprint, fluoroalkyl-modified PS in particular is observed to substantially reduce film adhesion to the mold, resulting in a nearly defect-free nanoimprint. Subsequent lithographic procedures revealed excellent graphoepitaxial alignment of sub-10 nm BCP microdomains, a critical step toward lower-cost, high-throughput nanofabrication.