Biological software for materials engineering.

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The road ahead

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Electronic nanodevices based on self-assembled metalloproteins

A key challenge of the current research in nanoelectronics is the realization of biomolecular devices. The use of electron-transfer proteins, such as the blue copper protein azurin (Az), is particularly attractive because of their natural redox properties and self assembly capability. We present in this work our results about the fabrication, characterization and modeling of devices based on such redox protein. The prototypes of biomolecular devices operate in the solid state and in air . The charge transfer process in protein devices can be engineered by using proteins with different redox centers (metal atoms) and by controlling their orientation in the solid state through different immobilization methods. A biomolecular electron rectifier has been demonstrated by interconnecting two gold nanoelectrodes with an azurin monolayer immobilized on SiO2. The device exhibits a clear rectifying behavior with discrete current steps in the positive wing of the current–voltage curve, which are ascribed to resonant tunnelling through the redox active center. On the basis of these results we have designed an azurin-based transistor. The three terminal device exhibits an ambipolar behavior as a function of the gate bias, thus opening the way to the implementation of a new generation of logic architecture, such as fully integrated biomolecular logic gate

Parametric Analysis of Piezoelectric Resonances of AlN Layouts for Vibrating Energy Harvesting

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News Story on Italy's MIT Disappoints

We were surprised by the tone and content of the News of the Week story by L. Margottini about the new Italian Institute of Technology (IIT) ("Italy's MIT grows, and so does controversy," 19 June, p. [1502][1]). The remark that international competition was ignored in recruiting IIT scientists is patently false. IIT, at its inception in 2005, set up international competitions for both senior and junior investigators. These positions were advertised widely in scientific journals, including Science and Nature . As a result of this international search, four of the six appointed IIT research directors come from abroad, and among junior appointments, one-third are Italians returning from abroad, one-third are Italians already residing in Italy, and one-third are foreigners. Also untrue is Margottini's reported concern that IIT's scientific roster includes big names who do not do the bulk of their work at IIT. Recently appointed senior scientists might continue working at a previous institution for some time while their laboratory space at IIT is refurbished and equipment is ordered. However, after this setup period they do their work onsite. Margottini's story is largely based on a report written by Mario Rasetti and Elio Raviola, who visited the institute on 6 June 2007, barely 11 months after the first directors were selected, and before any labs were operational. The IIT laboratories started in a 25,000-m2 facility that was first made available in January 2006. As such, Rasetti and Raviola's report was documenting a work in progress and was designed to monitor the early stages of the Institute's development. Their report reflects problems typical of the birth of new institutions. Nonetheless, the report was regarded, on balance, as positive, and IIT was indeed given continued support. The News story does not mention the substantial progress achieved by IIT in the past 2 years. After the review by Rasetti and Raviola, an independent international advisory board made an onsite evaluation of IIT in December 2008 and a general assessment in May 2009; both gave IIT a ringing endorsement. The May 2009 report concludes that "[i]n general, both the accomplishments of the past three years and the future plans seem excellent" (R. Horvitz, Nobel Laureate), and that "[t]he IIT initiative has been remarkably successful…the quality of the new members is very high and would be competitive in all highly developed countries" (P. Greengard, Nobel Laureate) ([ 1 ][2]). Like all major scientific endeavors, IIT has had some growing pains, but we believe it has a very bright future. The best evidence is something that Margottini overlooks in her article: Scores of excellent young Italian and foreign researchers have returned to Italy or come to Italy for the first time to work at IIT. 1. [↵][3] 1. E. Bizzi 2. et al ., "Evaluation report of Technical and Scientific Committee of the IIT-Foundation" (09 May 2009). [1]: /lookup/doi/10.1126/science.324_1502 [2]: #ref-1 [3]: #xref-ref-1-1 "View reference 1 in text

General aspects of Hertzian potentials modeling in integrated optics

This work introduces a novel time-domain numerical simulator of integrated optical waveguides. Only solutions of two scalar Helmholtz-equations are used in the evaluation of electric and magnetic Hertzian-potentials that yields the electromagnetic field in the time domain, and the frequency response by the discrete Fourier transform. All the field components are obtained directly from the scalar potentials, and are not interrelated as in finite-difference time domain method. The Hertzian potential method (HPM) considers the field-perturbation effect in proximity of the dielectric discontinuities by generators modeling and takes into account the numerical error of a wave that travels in a dielectric multilayered optical guide. We present in this work the general finite difference discretization and the numerical setting of the HPM related to optical waveguide full-wave modeling. Copyright © 2011 John Wiley & Sons, Ltd

Frequency and density dependent radiative recombination processes in III–V semiconductor quantum wells and superlattices

Abstract In this paper we review the radiative recombination processes occurring in semiconductor quantum wells and superlattices under different excitation conditions. We consider processes whose radiative efficiency depends on the photogenerated density of elementary excitations and on the frequency of the exciting field, including luminescence induced by multiphoton absorption, exciton and biexciton radiative decay, luminescence arising from inelastic excitonic scattering, and electron-hole plasma recombination. Semiconductor quantum wells are ideal systems for the investigation of radiative recombination processes at different carrier densities owing to the peculiar wavefunction confinement which enhances the optical non-linearities and the bistable behaviour of the crystal. Radiative recombination processes induced by multi-photon absorption processes can be studied by exciting the crystal in the transparency region under an intense photon flux. The application of this non-linear spectroscopy gives d..

Polarization effects in nitride semiconductors and device structures

Wide bandgap nitride semiconductors have recently attracted a great level of attention owing to their direct bandgaps in the visible to ultraviolet regions of the spectrum as emitters and detectors. Moreover, this material system with its favorable hetero-junctions and transport properties began to produce very respectable power levels in microwave amplifiers. If and when the breakdown fields achieved experimentally approach the predicted values, this material system would also be very attractive for power switching devices. In addition to the premature breakdown, high concentration of defects, and inhomogeneities, a number of scientific challenges remain including a clear experimental investigation of polarization effects. In this paper, following a succinct review of the progress that has been made, spontaneous and piezoelectric polarization effects and their impact on sample device-like hetero-structures will be treated

The State of Play on COVID-19 Vaccination in Pregnant and Breastfeeding Women: Recommendations, Legal Protection, Ethical Issues and Controversies in Italy

To date, extensive research has been conducted on vaccination against COVID-19 during pregnancy to verify the safety and efficacy of the vaccines, despite the fact that pregnant women were excluded from the initial clinical trials. The ever-increasing number of scientific publications has confirmed the absence of biological mechanisms associating mRNA vaccines with adverse effects in pregnancy and breastfeeding, although few studies have been carried out on their effect on fertility. While the Italian legal system provides for maternity protection measures and indemnity for vaccination damages pursuant to law no. 210/1992, it is not exempt from controversy. This contribution describes the state of play on COVID-19 vaccination in pregnant and lactating women, including: current recommendations for pregnant and lactating women; ethical issues related to vaccination hesitancy among pregnant women; the legislative paradox whereby sanctions may be imposed on women in certain professional categories who refuse vaccination because they are pregnant; and the possible legal consequences in the event of harm to the unborn child due to vaccination. All of this is considered in accordance with the principles of medical ethics, taking into account the national legislation