Laboratory of Nanotechnology Instrumentation and Optics

The sensitivity and specificity of ST-segment elevation in the right precordial lead V4R as an early indicator of right ventricular infarction were examined in a consecutive series of 110 patients admitted for acute inferior myocardial infarction. The sensitivity was 82.7%, the specificity 76.9% and the positive predictive value 70% in 58 patients with right ventricular infarction documented by autopsy or a combination of radionuclide ventriculography and one or more of the following tests: echocardiography, technetium-99m pyrophosphate scintigraphy and hemodynamic monitoring. The negative predictive value was 87.7%. Because of its simplicity and its high sensitivity and specificity, recording of V4R should be an intrinsic part of the early evaluation and electrocardiographic examination of acute inferior wall infarction.

The acute hemodynamic effects of an i.v. bolus of verapamil, 0.1 mg/kg or 0.06-0.075 mg/kg, were examined by serial radionuclide studies in 46 patients with coronary artery disease. In 20 patients with ejection fractions (EFs) greater than 35% (group 1A), verapamil, 0.1 mg/kg given over 1-11/2 minutes, had a biphasic effect: first, a transient decrease in EF accompanied by increased left ventricular (LV) volumes and cardiac output equivalents; then, an overshoot of EF to values above control, accompanied by a decrease in peripheral vascular resistance and a drastic decrease in LV volumes, while cardiac output equivalent remained slightly elevated. In eight patients with EFs less than 35% (group 1B), only the first effect on EF was noted. In 10 patients with EFs greater than 35% (group 2), verapamil, 0.06-0.075 mg/kg, exerted qualitatively similar but milder effects on hemodynamic function. Finally, verapamil, 0.1 mg/kg given more slowly, over 2-21/2 minutes, produced no significant changes in EF or LV volumes in another eight patients (group 3). The acute effects of verapamil are thus both time-related and dose-dependent. They are also related to the baseline functional reserve of the left ventricle. This study documents that verapamil exerts a depressant effect on LV function. However, the transient nature of this depression and the quick recovery to normal or above-normal values indicate that verapamil, in the doses used in this study, is safe to use intravenously in patients with coronary artery disease.

SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) is based on a very promising technology. It permits a drastic reduction of the size of spectrometers while conserving, even improving, their performances. We present the first attempt to realise a SWIFTS based on wave guides in glass operating in visible and near infra-red. Here, we present an original optical near-field detection in which nanowires of gold are used to directly sample the evanescent standing wave in the waveguide. With this first prototype we have been able to rebuild a spectrum with a resolution R=95.

Pediatric concussions are common and many children seek care in emergency departments. Providing concussion discharge instructions to patients and families is part of routine standard of care. The objective of this study was to determine whether the use of the Acute Concussion Evaluation-Emergency Department Discharge Instructions (ACE-ED DI) improves the caregiver's knowledge of injury management, specifics about returning to school and sports activities, and outpatient follow-up. This was a quasi-experimental study conducted in an urban Level 1 trauma center pediatric emergency department (PED). A convenience sample of caregivers of children aged 5-18 years who presented to the PED with a concussion was recruited and consented to participate. Caregivers completed a 16-item survey to assess overall understanding of concussion management after instructions were given. Caregivers received the standard discharge instructions (SDIs) in Phase 1 and SDIs plus the ACE-ED DI in Phase 2. Descriptive statistics were used for demographic variables and t-test to compare groups. Sixty-three of 68 (93%) caregivers participated; 30 in the SDI group and 33 in the SDI plus ACE-ED DI group. Demographic characteristics were similar between groups. Caregivers who received the ACE-ED DI reported a 24% increase in helpfulness of written materials (p < 0.001), a 25% increase in perceived understanding about concussion injury and management (p < 0.001), a 23% increase in understanding about returning to school activities (p < 0.001), and were 17% more likely to follow up with their primary care provider (p < 0.001). The ACE-ED DI used in a PED was found to be more effective at increasing caregivers' perceived knowledge of concussion management, specifics about returning to school and sports activities, and outpatient follow-up.

The size and the weight of current spectrometers is a serious issue regarding various applications, however the technologies used in existing spectrometers prevent them from substantial improvement. SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) is a new familyof spectrometers based on a verypromising technology. It is based on an original wayto fully sample the Fourier interferogram obtained in a waveguide byeither a reflection (SWIFTS Lippmann) or counter-propagative (SWIFTS Gabor) interference phenomenon. The sampling can be simultaneouslydone without anymo ving part thanks to "nano-detectors" located in the evanescent field of the waveguide. It allows a dramatic reduction of the size and the weight of spectrometers while improving their performances (high stabilityand high resolution &delta;&sigma; &lt; 1cm^-1). Here, we present the development status of the SWIFTS Gabor and the results obtained (resolution of 4cm^-1) with existing technical solutions for the "nano-detectors" in visible and near infrared.

Current voltage and Kelvin Probe Force Microscopy (KPFM) measurements were performed on single ZnO nanowires. Measurements are shown to be strongly correlated with the contact behavior, either ohmic or Schottky. The ZnO nanowires were obtained by metallo-organic chemical vapor deposition (MOCVD) and contacted using electronic-beam lithography. Depending on the contact geometry, good quality ohmic contacts (linear I V behavior) or non-linear (diode like) Schottky contacts were obtained. Current voltage and KPFM measurements on both types of contacted ZnO nanowires were performed in order to investigate their behavior. A clear correlation could be established between the I V curve, the electrical potential profile along the device and the nanowire geometry. Some arguments supporting this behavior are given based on a depleted region extension. This work will help to better understand the electrical behavior of ohmic contacts on single ZnO nanowires, for future applications in nanoscale field effect-transistors and nano-photodetectors.

Nowadays, integrated photonics is a key technology in quantum information processing (QIP) but achieving all-optical buses for quantum networks with efficient integration of single photon emitters remains a challenge. Photonic crystals and cavities are good candidates but do not tackle how to effectively address a nanoscale emitter. Using a nanowire nanowaveguide, we realise an hybrid nanodevice which locally excites a single photon source (SPS). The nanowire acts as a passive or active sub-wavelength waveguide to excite the quantum emitter. Our results show that localised excitation of a SPS is possible and is compared with free-space excitation. Our proof of principle experiment presents an absolute addressing efficiency ηa = 10-4 only 50% lower than the one using free-space optics. This important step demonstrates that sufficient guided light in a nanowaveguide made of a semiconductor nanowire is achievable to excite a single photon source. We accomplish a hybrid system offering great potentials for electrically driven SPSs and efficient single photon collection and detection, opening the way for optimum absorption/emission of nanoscale emitters. We also discuss how to improve the addressing efficiency of a dipolar nanoscale emitter with our system.

This paper deals with a new spectrograph on integrated optics. It is composed of an Y-junction where the two junction arms are guided in a loop structure in order to obtain an interference pattern. The measurement of this intensity distribution gives access to the optical spectrum source after a Inverse Fourier Transform. To measure it, we use the property of the loop composed of a bent waveguide which is a leaky structure. Depending on the radius of the bent waveguide, a part of the light leaks from the waveguide to outside. The radiated power, proportional to the intensity in the waveguide, is coupled into a plan waveguide set near the bent waveguide. Indeed the two structures are separated by a gap which changes along the periphery of the loop. This structure enables both to control the leaking light part and to confine in the plan waveguide the propagation of the radiated field. Thereby, the radiated intensity is measured at a peculiar distance of the loop on a perpendicular plan to the input waveguide. So, the interference pattern measured is magnified by the ratio of the plan waveguide length over the loop radius, allowing to use a commercial photodetectors array to sufficiently sample the interference pattern. The spectrum is finally obtained operating a Discrete Fourier Transform. The device modelization is divided in two parts. The first part describes the coupling between the bent and the plan waveguide modelised by a modal method based on a Fourier series expansion (RCWA) combined with an exponential conformal mapping in order to simulate the electromagnetic field near the loop. The second part describes the Helmholtz-Kirchhoff theorem to simulate the far-electromagnetic field. From the interference pattern modelized, the spectrum of the signal is then calculated. A demonstrator in integrated optics on glass is being developed.

We propose a plasmonic device consisting of a concentric ring grating acting as an efficient tool for directional launching and detection of surface plasmon-polaritons (SPPs). Numerical simulations and optical characterizations are used to study the fabricated structured gold surface. We demonstrate that this circularly symmetrical plasmonic device provides an efficient interface between free space radiation and SPPs. This structure offers an excellent platform for the study of hybrid plasmonics in general and of plasmon-emitter couplings in particular, such as those occurring when exciting dye molecules placed inside the ring. As illustrated in this work, an interesting property of the device is that the position of excitation determines the direction of propagation of the SPPs, providing a flexible mean of studying their interactions with molecules or dipole-like emitters placed on the surface.

Međunarodni znanstveni skup Desničini susreti 2016. održan je u Beogradu, u Institutu za književnost i umetnost i u Biblioteci grada Beograda, 23., 24. i 25. rujna 2016. godine. Tema je bila „Hrvatsko-srpski/srpsko-hrvatski interkulturalizam danas. Povodom 110. obljetnice rođenja Vladana Desnice“. 1 Realiziran je kao obveza u međudržavnom hrvatsko-srpskom projektu „‘Desničini susreti’ i hrvatsko-srpski/srpsko-hrvatski interkulturalizam“ Instituta za književnost i umetnost u Beogradu i Centra za komparativnohistorijske i interkulturne studije Filozofskog fakulteta Sveučilišta u Zagrebu odobrenom za 2016./2017. i 2017./2018. godinu. Zbornik radova – koji se i ove godine tradicionalno objavljuje na godišnjicu održavanja skupa – čine dvadeset i četiri autorska članka, koje je pojedinačno recenziralo u načelu dvoje recenzenata, po jedan od Hrvatske i Srbije, a ukupno njih trideset i osam. Zbornik je i kao cjelinu ocijenilo dvoje recenzenata (znanstvena savjetnica dr. sc. Vesna Matović i prof. dr. sc. Dušan Marinković). Priopćenja i žive rasprave na skupu, redovito sadržajne i obrazložene recenzentske ocjene, razmjene mišljenja članova Uređivačkog odbora i urednikove komunikacije čine cjelinu iskustva sažetu u ovom Zborniku radova. Navedena je cjelina time i sama izvorni doprinos hrvatsko-srpskom/srpsko-hrvatskom interkulturalizmu.

Zinc oxide (ZnO) epitaxial thin films grown on c-sapphire substrates by pulsed laser deposition were investigated using angle and polarization-resolved photoluminescence spectroscopy. Side-emission spectra differed significantly from surface-emission spectra in exhibiting dominant, narrow, polarization-resolved peaks. These spectral features were attributed to leaky substrate modes in the layers. Observations were first verified using transmission calculations with non-adjustable parameters, which took into account the dispersion, the anisotropy of the ZnO refractive index and the dependence on film thickness. Results were consistent with Fabry-Perot-like interference being the origin of the distinctive ZnO luminescence observed at grazing incidence angles. A second analysis, based on the source terms method, was used in order to retrieve the bulk emission properties, including the wavelength-dependent quantum yield and the emission anisotropy. While ZnO thin films were considered here, this analysis method can be extended to any luminescent thin film of similar geometry, demonstrating the potential of leaky mode analysis for probing passive and active material properties.

Zinc oxide (ZnO) epitaxial thin films grown on c-sapphire substrates by\npulsed laser deposition were investigated using angle and polarization-resolved\nphotoluminescence spectroscopy. Side-emission spectra differed significantly\nfrom surface-emission spectra in exhibiting dominant, narrow,\npolarization-resolved peaks. These spectral features were attributed to leaky\nsubstrate modes in the layers. Observations were first verified using\ntransmission calculations with non-adjustable parameters, which took into\naccount the dispersion, the anisotropy of the ZnO refractive index and the\ndependence on film thickness. Results were consistent with Fabry-Perot-like\ninterference being the origin of the distinctive ZnO luminescence observed at\ngrazing incidence angles. A second analysis, based on the source terms method,\nwas used in order to retrieve the bulk emission properties, including the\nwavelength-dependent quantum yield and the emission anisotropy. While ZnO thin\nfilms were considered here, this analysis method can be extended to any\nluminescent thin film of similar geometry, demonstrating the potential of leaky\nmode analysis for probing passive and active material properties.\n