A. Kotlicki

Planar array of superheated superconductors: An improved superheated superconducting granule detector

We have invented a new superheated superconducting granule detector which is a prime candidate for sensing dark matter and which could prove very useful for other applications. The sensor element is a planar array of spherical granules for which the spread in transition temperatures is nearly an order of magnitude smaller than that for a colloidal device. The detecting efficiency for low‐energy deposition is thereby significantly increased. Preliminary results are described.

39.1: New Reflective Color Display Technique Based on Total Internal Reflection and Subtractive Color Filtering

We present a reflective color display technique using a configuration of subtractive color filtering regions to control total internal reflection (TIR) in prismatic microstructures. The ability of the prismatic surface to efficiently redirect ambient light rays toward the viewer and the use of subtractive color filters result in a bright, easily legible, low power color image which has a four-fold improvement in reflectivity over conventional RGB reflective LCD displays. A key advantage of this technique is the ability to switch between the highly reflective and intensely colored states with only about a half-micron movement of the controllable subtractive color filter.

Pulsed nuclear magnetic resonance of oriented nuclei in an insulating magnetic material:54Mn−MnCl2.4H2O

The first observation of pulsed nuclear magnetic resonance of oriented nuclei in an insulating magnetic material is reported. The system studied was the ordered antiferromagnet54Mn−MnCl2.4H2O. The response of the54Mn spins to a single pulse of variable length, the free induction decay, and Hahn spin-echo have all been observed. A discussion of the transverse decoherent relaxation timeT2 in MnCl2.4H2O is given.

Vibrational characteristics of harp soundboards

Harps exist in different forms, from large factory-made concert harps to small hand-made folk harps. This variety presents both a challenge and an opportunity for acousticians. The musical quality of a harp depends on many factors, but key among these is the soundboard. This work sets out to define some general desirable qualities of a harp soundboard. First, in order to understand the relationship between the vibrational behavior of a bare soundboard and that of a completed instrument, a 36-string harp was built from scratch. Measurements were made at each stage of construction, and the results showed how the bare soundboard properties affect those of the finished harp. Second, the soundboards of several harps of different sizes were assessed by measuring the admittances along the string bar. These data showed that one relationship crucial to the quality of the soundboard is that between the modal shapes and modal frequencies of the soundboard, and the position and fundamental frequencies of the strings attached to it. A general statement is made about this relationship, one which should be of use to harp makers.

Novel resonant-frequency sensor to detect the kinetics of protein adsorption

Proteins prefer interfaces, and in aqueous solutions they rapidly adsorb to available solid–liquid interfaces. The adsorption process often involves a change in protein conformation at the surface that can result in functional inactivation of the protein. These changes in protein conformation, which are thought to lead to the formation of an entangled gel-like layer of denatured protein, are responsible for a number of deliterious processes, including biofouling on contact lenses and medical implants. The adsorption process is generally irreversible; dilution of protein in the solution phase does not result in protein desorption from the solid. Presumably, this is due to the effects of the protein denaturation and entanglement process on the rate constant for desorption. Nonspecific protein adsorption to solid–liquid interfaces is, therefore, a kinetically controlled process. Hence, measuring and understanding the kinetics of protein adsorption to solid surfaces, including the kinetics of protein conforma...

Modulation of retroreflection by controlled frustration of total internal reflection

Retroreflective images are useful in outdoor application for which high legibility is required both during the day and in response to vehicular illumination. To date, all variable message retroreflective images have employed mechanical shutters as the switching mechanism. As an alternative, we propose a method for switching the total internal reflection effect used in retroreflectors by means of pneumatic actuation of surface treated polydimethylsiloxane gel. This approach is both effective and compatible with current large-scale manufacturing methods.

First observation of double quantum nuclear magnetic resonance of oriented nuclei

Abstract Double quantum nuclear magnetic resonance of oriented nuclei has been observed for the first time. The systems studied were 54MnMnCl2·4H2O and 54MnMn (COOCH3)2·4H2O and rotation patterns, free induction decays and spin echoes all have been observed. The double quantum signal can be significantly larger than the single quantum signal.

Recent developments in superheated superconducting granular detectors

Abstract The operation of a superheated superconducting granular detector with a SQUID readout is described, and the advantages and limitations of the colloidal device discussed. A new sensor consisting of a planar array of granules is described and results demonstrating an order of magnitude decrease in the spread of transition temperatures are presented.

Vibro-acoustic characteristics of an Aoyama Amphion concert harp

The mechanical admittance of the soundboards of four full-size concert harps from three manufacturers was measured, and the results show that there is little variation between them. More detailed vibro-acoustic data were then obtained for an Aoyama Amphion harp. Analysis of these data show that the individual soundholes amplify the radiated sound in successive frequency bands associated with the modal frequencies of the soundboard. The lower holes tend to contribute at the lower end of the frequency scale, and the higher holes at the higher end of the scale.

Neutron detection using a planar array of superheated superconductors

Abstract A new thermal neutron detector consisting of an indium/mylar PASS array with a filler of boron powder has been tested successfully. A boron nucleus captures a neutron and the α-particle emitted in this reaction nucleates the transition to the normal state in a neighbouring grain. A PASS with grain radius r = 12 μ m showed very low response to irradiation by 835 keV γ-rays. The same PASS responded to α-particles with high efficiency, and thermal neutrons were detected with good efficiency and very low background. Thermal neutrons were also counted with an R = 25 μ m PASS. The use of large granules will allow spatial resolution to a single grain to be obtained and a read-out based on conventional inductive coupling and fast electronics to be utilized.