"SAMs meet MEMS": surface modification with self-assembled monolayers for the dry-demolding of photoplastic MEMS/NEMS

In this contribution we demonstrate the use of self-assembled monolayers (SAMs) as anti-adhesion coating to assist the removal of photoplastic MEMS/NEMS with a patterned metal layer from the surface without wet chemical sacrificial layer etching, so-called 'dry-demolding'. The SAMs functionality here is to reduce the stiction between the surface and a thin evaporated metal film. The double-layer SAM/metal provides enough stability to support subsequent micromachining step

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

A self-assembled monolayer-assisted surface microfabrication and release technique

This paper describes a method of thin film and MEMS processing which uses self-assembled monolayers as ultra-thin organic surface coating to enable a simple removal of microfabricated devices off the surface without wet chemical etching. A 1.5-nm thick self-assembled monolayer of dodecyltrichlorosilane reduces the adhesion between the SiO2 substrate surface and a 100-nm thick evaporated aluminum film. A 100-mm thick layer of photoplastic SU-8, which is spun and structured by lithography and development on top of the monolayer/aluminum sandwich layer, can be mechanically lifted off the surface with the aluminum layer. The organic monolayer provides enough stability for the microfabrication process including photoresist spinning and thermal steps. The aluminum film has a surface roughness of less than 1 nm rms as measured by AFM. Photolithographic microstructuring of the aluminum film prior to the photoplastic process allows for transparent embedded bottom-side metal electrodes. As first application example, molded nanoprobes for scanning near-field optical microscopy, has been demonstrated using this technique

Heterogeneous Nuclear Ribonucleoprotein K Interacts with Abi-1 at Postsynaptic Sites and Modulates Dendritic Spine Morphology

BACKGROUND: Abelson-interacting protein 1 (Abi-1) plays an important role for dendritic branching and synapse formation in the central nervous system. It is localized at the postsynaptic density (PSD) and rapidly translocates to the nucleus upon synaptic stimulation. At PSDs Abi-1 is in a complex with several other proteins including WASP/WAVE or cortactin thereby regulating the actin cytoskeleton via the Arp 2/3 complex. PRINCIPAL FINDINGS: We identified heterogeneous nuclear ribonucleoprotein K (hnRNPK), a 65 kDa ssDNA/RNA-binding-protein that is involved in multiple intracellular signaling cascades, as a binding partner of Abi-1 at postsynaptic sites. The interaction with the Abi-1 SH3 domain is mediated by the hnRNPK-interaction (KI) domain. We further show that during brain development, hnRNPK expression becomes more and more restricted to granule cells of the cerebellum and hippocampal neurons where it localizes in the cell nucleus as well as in the spine/dendritic compartment. The downregulation of hnRNPK in cultured hippocampal neurons by RNAi results in an enlarged dendritic tree and a significant increase in filopodia formation. This is accompanied by a decrease in the number of mature synapses. Both effects therefore mimic the neuronal morphology after downregulation of Abi-1 mRNA in neurons. CONCLUSIONS: Our findings demonstrate a novel interplay between hnRNPK and Abi-1 in the nucleus and at synaptic sites and show obvious similarities regarding both protein knockdown phenotypes. This indicates that hnRNPK and Abi-1 act synergistic in a multiprotein complex that regulates the crucial balance between filopodia formation and synaptic maturation in neurons

Structure, bonding and morphology of hydrothermally synthesised xonotlite

The authors have systematically investigated the role of synthesis conditions upon the structure and morphology of xonotlite. Starting with a mechanochemically prepared, semicrystalline phase with Ca/Si=1, the authors have prepared a series of xonotlite samples hydrothermally, at temperatures between 200 and 250 degrees C. Analysis in each case was by X-ray photoelectron spectroscopy, environmental scanning electron microscopy and X-ray diffraction. The authors’ use of a much lower water/solid ratio has indirectly confirmed the ‘through solution’ mechanism of xonotlite formation, where silicate dissolution is a key precursor of xonotlite formation. Concerning the role of temperature, too low a temperature (~200 degrees C) fails to yield xonotlite or leads to increased number of structural defects in the silicate chains of xonotlite and too high a temperature (>250 degrees C) leads to degradation of the xonotlite structure, through leaching of interchain calcium. Synthesis duration meanwhile leads to increased silicate polymerisation due to diminishing of the defects in the silicate chains and more perfect crystal morphologies

Surface Modification With Self-Assembled Monolayers for Nanoscale Replication of Photoplastic MEMS

A release technique that enables to lift microfabricated structures mechanically off the surface without using wet chemistry is presented. A self-assembled monolayer of dodecyltrichlorosilane forms a very uniform 1.5-nm-thick anti-adhesion coating on the silicon dioxide surface, on full wafer scale. The structural layers are formed directly onto the organic layer. They consist here of a 100-nm-thick aluminum film and a high-aspect ratio photoplastic SU-8 structure. After the microfabrication the structure can be lifted off the surface together with the aluminum layer. This generic technique was used to make a variety of novel structures. First, aluminum electrodes that are embedded in plastic are made using lithography, etching and surface transfer techniques. Second, using a patterned monolayer as defined by microcontact printing, resulted in a spatial variation of the surface adhesion forces. This was used to directly transfer the stamped pattern into a metal structure without using additional transfer etching steps. Third, the monolayer’s ability to cover surface features down to nanometer scale was exploited to replicate sharp surface molds into metal coated photoplastic tips with 30-nm radii for use in scanning probe instruments such as near-field optical techniques. The advantage compared to standard sacrificial layer techniques is the ability of replication at the nanoscale and the absence of etchants or solvents in the final process steps

A modified surgical technique in the management of eyelid burns: a case series

<p>Abstract</p> <p>Introduction</p> <p>Contractures, ectropion and scarring, the most common sequelae of skin grafts after eyelid burn injuries, can result in corneal exposure, corneal ulceration and even blindness. Split-thickness or full-thickness skin grafts are commonly used for the treatment of acute eyelid burns. Plasma exudation and infection are common early complications of eyelid burns, which decrease the success rate of grafts.</p> <p>Case presentation</p> <p>We present the cases of eight patients, two Chinese women and six Chinese men. The first Chinese woman was 36 years old, with 70% body surface area second or third degree flame burn injuries involving her eyelids on both sides. The other Chinese woman was 28 years old, with sulfuric acid burns on her face and third degree burn on her eyelids. The six Chinese men were aged 21, 31, 38, 42, 44, and 55 years, respectively. The 38-year-old patient was transferred from the ER with 80% body surface area second or third degree flame burn injuries and third degree burn injuries to his eyelids. The other five men were all patients with flame burn injuries, with 7% to 10% body surface area third degree burns and eyelids involved. All patients were treated with a modified surgical procedure consisting of separation and loosening of the musculus orbicularis oculi between tarsal plate and septum orbital, followed by grafting a large full-thickness skin graft in three days after burn injury. The use of our modified surgical procedure resulted in 100% successful eyelid grafting on first attempt, and all our patients were in good condition at six-month follow-up.</p> <p>Conclusions</p> <p>This new surgical technique is highly successful in treating eyelid burn injuries, especially flame burn injuries of the eyelid.</p

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