DMD-specific FISH probes are diagnostically useful in the detection of female carriers of DMD gene deletions

The challenge of Duchenne muscular dystrophy (DMD) carrier identification resides in the ability to identify the presence of a mutant gene over the background contributed by the normal allele. Current diagnosis of carrier status when a deletion has been identified in a proband is based on an analysis of a gene dosage. We present a diagnostic strategy that uses fluorescence in situ hybridization (FISH) to detect female carriers with major deletions in the dystrophin gene. We screened a human X-chromosome-derived genomic library with a full-length dystrophin cDNA and isolated 15 dystrophin-specific cosmids that contain DMD gene exons. Six cosmids were further tested as FISH probes in control individuals and subsequently applied on chromosomes from eight males with DMD and known deletions and on samples from three female carriers. As expected, X chromosomes in normal females displayed four signals, two for the DMD-specific probe and two for the X-chromosome centromeric probe. Hybridization on chromosomal spreads from carriers of deletions revealed only one signal from the DMD-specific probe and two from the control centromeric probe. Males carrying deletions showed no DMD-specific signal for the deleted exons tested. Our data indicate that FISH could represent an alternative method for the detection of female carriers with DMD gene deletions.     

Aqueous Processing and Stabilization of Manganese Zinc Ferrite Powders via a Passivation–Dispersion Approach

A dispersion scheme for aqueous processing of manganese zinc ferrite suspensions is presented. The addition of oxalic acid leads to the formation of a uniform negative charge on the surface such that a cationic polyelectrolyte, polyethyleneimine (PEI), adsorbs and provides electrosteric dispersion. At 0.5 w/w (weight percent with respect to the dry powder) oxalic acid addition, there is a relatively uniform negative surface charge (approximately −30 mV) within the suspension pH range investigated (3–10), eliminating the isoelectric point (pH ∼7.6) present for the as-received metal oxide powder. At the addition of 0.5 w/w PEI on an oxalate-treated surface, the surface charge is constant and positive (∼20 mV) through a wide pH range, ∼5–10. The resulting rheological data for passivation–dispersion of relatively high-solids manganese zinc ferrite suspensions (∼80 wt%) demonstrate improved colloid stability with improved rheological properties. The resulting apparent viscosity and Bingham yield point is 0.01 Pa·s (12.0 cP) and 0.24 Pa (2.4 dynes/cm²), respectively. A sulfonated napthalene-based dispersant, typically used in industry, gives an apparent viscosity and Bingham yield point of 0.03 Pa·s (32 cP) and 3.1 Pa (31 dynes/cm²), respectively.     

Sunflower oil diesel fuel: Engine wear implications

Diesel lubricating oil contaminated with sunflower oil fuel was degraded under conditions simulating an engine crankcase environment for metal wear testing. Wear analyses were performed using a fourball apparatus according to ASTM D 4172. Lubricity of oils was characterized by ball scar dimensions. Contaminated lubricating oils exhibited lower metal wear indexes than pure lube oil control samples, even when the former were severely degraded as measured by thickening and loss of alkaline reserve.     

Electrophoretic deposition of carbon nanotubes

Electrophoretic deposition (EPD) has been gaining increasing interest as an economical and versatile processing technique for the production of novel coatings or films of carbon nanotubes (CNTs) on conductive substrates. The purpose of the paper is to present an up-to-date comprehensive overview of current research progress in the field of EPD of CNTs. The paper specifically reviews the preparation and characterisation of stable CNT suspensions, and the mechanism of the EPD process; it includes discussion of pure CNT coatings and CNT/nanoparticle composite films. A complete discussion of the EPD parameters is presented, including electrode materials, deposition time, electrode separation, deposition voltage and resultant electric field. The paper highlights potential applications of the resulting CNT and CNT/composite structures, in areas such as field emission devices, fuel cells, and supercapacitors.     

Re-inventing the electrical machines curriculum

Undergraduate courses in electromechanical energy conversion are typically oriented toward the steady-state analysis of electrical machines. The advent of low-cost computer power and the availability of numerical software tools provide the opportunity to fundamentally reorient the pedagogical approach to the topic. A new approach is consistent with the developing need to emphasize the study of new machine designs and machines employed for control purposes as well as machines for use in more traditional power applications. This paper presents the results obtained from simulations developed as an integral part of an undergraduate electrical machines course at the University of Dayton, USA. Sample simulation files are presented to demonstrate the ease with which the matrix model of the machine is transferred to the program. The matrix models and simulation results of the following machines are included: the single-phase transformer; the variable-reluctance machine; the cylindrical-rotor dual-winding machine; the symmetrical two-phase induction motor; a PWM-controlled DC machine; and an inverter-driven brushless machine. The selected machines provide a systematic framework for analysis and simulation and present problems of increasing complexity to the student     

Mentor modeling: the internalization of modeled professional thinking in an epistemic game

Players of epistemic games – computer games that simulate professional practica – have been shown to develop epistemic frames: a profession's particular way of seeing and solving problems. This study examined the interactions between players and mentors in one epistemic game, Urban Science. Using a new method called epistemic network analysis, we explored how players develop epistemic frames through playing the game. Our results show that players imitate and internalize the professional way of thinking that the mentors model, suggesting that mentors can effectively model epistemic frames, and that epistemic network analysis is a useful way to chart the development of learning through mentoring relationships.     

Bioactive ceramic coatings containing carbon nanotubes on metallic substrates by electrophoretic deposition

A range of potentially bioactive ceramic coatings, based on combinations of either hydroxyapatite (HA) or titanium oxide nanoparticles with carbon nanotubes (CNTs), have been deposited on metallic substrates, using electrophoretic deposition (EPD). Sol–gel derived, ultrafine HA powders (10–70 nm) were dispersed in multi-wall nanotube-containing ethanol suspensions maintained at pH = ∼3.5 and successfully coated onto Ti alloy wires at 20 V for 1–3 min For TiO₂/CNT coatings, commercially available titania nanopowders and surface-treated CNTs in aqueous suspensions were co-deposited on stainless steel planar substrates. A field strength of 20 V/cm and deposition time of 4 min were used working at pH = 5. Although the co-deposition mechanism was not investigated in detail, the evidence suggests that co-deposition occurs due to the opposite signs of the surface charges (zeta potentials) of the particles, at the working pH. Electrostatic attraction between CNTs and TiO₂ particles leads to the creation of composite particles in suspension, consisting of TiO₂ particles homogenously attached onto the surface of individual CNTs. Under the applied electric field, these net negatively charged “composite TiO₂/CNT” elements migrate to and deposit on the anode (working electrode). The process of EPD at constant voltage conditions was optimised in both systems to achieve homogeneous and reasonably adhered deposits of varying thicknesses on the metallic substrates_.     

Three‐Dimensional Internal Order in Multiwalled Carbon Nanotubes Grown by Chemical Vapor Deposition (Adv. Mater. 6/2005)

Unprecedented levels of internal order are obtained in multiwalled carbon nanotubes grown by chemical vapor deposition with a nitrogen‐doping level of 3% in work reported by Windle and co‐workers on p. 760. Not only is each of the tubular layers of the same orientation (chirality), but they also appear to be in three‐dimensional crystallographic register with one another as shown by the hkl reflections on the cover. The tubes are also straighter and thicker than pure carbon equivalents. The layers are either pure zigzag or pure armchair with spacings close to that of graphite.     

Extended tuning of an injection-locked diode laser

We have investigated the application of an electronic feedback technique recently reported by Repasky et al. [Appl. Opt. 45, 9013 (2006)] to an injection-locked semiconductor diode laser. We find that without electronic feedback, the injection-locked slave laser will only follow the master for less than 1 GHz, but once the electronic feedback is applied, the slave laser is capable of following for more than 20 GHz, corresponding to the full scan range of the master laser.