Reinventing Butyl Rubber for Stretchable Electronics

The development of stretchable electronic devices that are soft and conformable has relied heavily on a single material—polydimethylsiloxane—as the elastomeric substrate. Although polydimethylsiloxane has a number of advantageous characteristics, its high gas permeability is detrimental to stretchable devices that use materials sensitive to oxygen and water vapor, such as organic semiconductors and oxidizable metals. Failing to protect these materials from atmosphere‐induced decomposition leads to premature device failure; therefore, it is imperative to develop elastomers with gas barrier properties that enable stretchable electronics with practical lifetimes. Here, butyl rubber—a material with an intrinsically low gas permeability traditionally used in the innerliners of tires to maintain air pressure—is reinvented for stretchable electronics. This new material is smooth and optically transparent, possesses the low gas permeability typical of butyl rubber, and vastly outperforms polydimethylsiloxane as an encapsulating barrier to prevent the atmospheric degradation of sensitive electronic materials and the premature failure of functioning organic devices. The merits of transparent butyl rubber presented here position this material as an important counterpart to polydimethylsiloxane that will enable future generation stretchable electronics.     

On the non-blocking conditions of self-routeing multistage interconnection networks

This paper studies the non-blocking conditions of a generic N × N multistage interconnection network, such as an omega network or an n-cube network, in which only one path connects any inlet to each outlet and different I/O paths can share interstage links. It is widely known that any of these networks is non-blocking for a compact and monotone pattern of k ≤ N I/O paths. Recently it has become very important to show the network non-blocking property for permutation sets, wider than the compact and monotone, which are usually encountered in broadband ATM networks. By using a new approach based on the concept of distance between I/O paths, we show here that these networks are non-blocking for a set of I/O paths obtained by shifting cyclically the inlets of a compact and monotone pattern of I/O paths by an arbitrary number of steps.     

New optically pumped FIR laser lines in CD3OH

In this work we report laser action in 69 new FIR laser lines in CD₃OH optically pumped by a regular cw CO₂ laser. We have performed measurements of laser wavelength, optimum pressure of the gas, relative polarization and intensity on all lines, including some previously known.     

A review of colonoscopy in 200 patients

During the examination of the colon by fibre-optic colonoscopy in 200 consecutive patients it was possible to reach the caecum or suspected lesion in 80% of cases. Careful bowel preparation, sedation and detailed attention to techniques described are necessary for safe and successful performance of this procedure. In 85% of examinations, colonoscopy produced positive results including the definition of uncertain radiological lesions in 45 patients, finding of a cause for rectal bleeding not shown on barium studies in 15 patients, the assessment of inflammatory bowel disease in 28 patients, and the removal of polyps in 40 patients. Important was the finding of a normal colon in 49 cases, which obviated unnecessary surgery. Colonic perforation occurred in 2 patients. The limitations and complications of the procedure must be realised, but it is concluded that the colonoscope provides a valuable and effective means of diagnosis and therapy of lesions in the large bowel.     

Reciprocal effects of thyroxine and triiodothyronine on their deiodination by rat tissues in vitro

The reciprocal effects of loading doses of thyroxine (T4) or triiodothyronine (T3) on the deiodination of their 125iodine-labelled isotopes by rat muscle and liver homogenates were studied. In 21 experiments muscle homogenates deiodinated a mean 45.0% of a tracer dose of [125I]T4 and 18.0% of [125I]T3. On addition of graded amounts of nonradioactive T4 or T3 the percentual deiodination of both labelled hormones progressively declined. This effect was significantly greater in homogenates incubated with non-radioactive T4, thus reflecting a stronger affinity of this hormone for muscle deiodinating sites. This correlate with the greater displacment of [125I]T3 as revealed by the percentage of recovered labelled hormone. In 18 experiments liver homogenates deiodinated a mean 14.6% of a tracer amount of [125I]T4 and 8.5% of [125I]T3. The addition of a T4- or a T3-load was followed by a smaller decrease in percentual deiodination of both labelled hormones as compared to muscle homogenates. Unlike the effects observed in muscle, the breakdown of [125I]T4 and [125I]T3 by liver homogenates was equally affected by similar amounts of stable T4 or T3. It is concluded that in the present in vitro system T4 and T3 share cellular sites of deiodination in rat muscle and liver and that, at least in muscle, which constitutes over one-half of the rat body weight T4 appears to be preferentially deiodinated.