Design of a Slab Tamm Plasmon Resonator Coupled to a Multistrip Array Waveguide for the Mid Infrared.

In this work, we present and analyze a design of an absorber-waveguide system combining a highly sensitive waveguide array concept with a resonant selective absorber. The waveguide part is composed of an array of coupled strip waveguides and is therefore called a coupled strip array (CSA). The CSA is then coupled to the end of a slab Tamm plasmon (STP-) resonator, which is composed of a quasicrystal-like reflector formed by the patterning of a silicon slab and an interfacing tungsten slab.

Ultra-Narrow SPP Generation from Ag Grating.

In this study, we investigate the potential of one-dimensional plasmonic grating structures to serve as a platform for, e.g., sensitive refractive index sensing.

Figures of merit for mid-IR evanescent-wave absorption sensors and their simulation by FEM methods.

Proper optimization of a photonic structure for sensing applications is of extreme importance for integrated sensor design. Here we discuss on the definition of suitable parameters to determine the impact of photonic structure designs for evanescent-wave absorption sensors on the achievable resolution and sensitivity. In particular, we analyze the most widespread quantities used to classify photonic structures in the context of sensing, namely the evanescent-field ratio (or evanescent power factor) and the confinement factor Γ.

Design of a Curved Shape Photonic Crystal Taper for Highly Efficient Mode Coupling.

The design and modeling of a curved shape photonic crystal taper consisting of Si rods integrated with a photonic crystal waveguide are presented. The waveguide is composed of a hexagonal lattice of Si rods and optimized for CO sensing based on absorption spectroscopy. We investigated two different approaches to design a taper for a photonic crystal waveguide in a hexagonal lattice of silicon rods.

Impact of Different Metals on the Performance of Slab Tamm Plasmon Resonators.

We investigate the concept of slab Tamm plasmons (STP) in regard to their properties as resonant absorber or emitter structures in the mid-infrared spectral region. In particular, we compare the selective absorption characteristics resulting from different choices of absorbing material, namely Ag, W, Mo or highly doped Si. We devised a simplified optimization procedure using finite element simulations for the calculation of the absorption together with the application of micro-genetic algorithm (GA) optimization.

A CMOS Compatible Pyroelectric Mid-Infrared Detector Based on Aluminium Nitride.

The detection of infrared radiation is of great interest for a wide range of applications, such as absorption sensing in the infrared spectral range. In this work, we present a CMOS compatible pyroelectric detector which was devised as a mid-infrared detector, comprising aluminium nitride (AlN) as the pyroelectric material and fabricated using semiconductor mass fabrication processes. To ensure thermal decoupling of the detector, the detectors are realized on a SiN/SiO membrane.

Mapping of exciton-exciton annihilation in MEH-PPV by time-resolved spectroscopy: experiment and microscopic theory.

Transient absorption traces taken on samples of the polymer MEH-PPV are measured as a function of the laser intensity. In increasing the laser power, different decay dynamics of the signal are obtained. This suggests that effective exciton-exciton annihilation takes place.

The role of the dipolar neighborhood on the relaxation dynamics of multichromophoric merocyanines.

The interactions between different chromophores within a molecular system are crucial to comprehend relaxation dynamics, regardless if one deals with small molecules or larger systems like polymers or aggregates. We investigate a series of merocyanine molecules that contain one, two or three highly dipolar (μg = 13.1 D) dyes in close vicinity to study the influence and origin of interactions, e.

Relaxation dynamics and exciton energy transfer in the low-temperature phase of MEH-PPV.

Understanding the effects of aggregation on exciton relaxation and energy transfer is relevant to control photoinduced function in organic electronics and photovoltaics. Here, we explore the photoinduced dynamics in the low-temperature aggregated phase of a conjugated polymer by transient absorption and coherent electronic two-dimensional (2D) spectroscopy. Coherent 2D spectroscopy allows observing couplings among photoexcited states and discriminating band shifts from homogeneous broadening, additionally accessing the ultrafast dynamics at various excitation energies simultaneously with high spectral resolution.

Ultrafast Energy Transfer between Disordered and Highly Planarized Chains of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV).

Upon cooling a solution of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), a phase transition occurs, leading to the formation of aggregates. We have studied the dynamics of singlet excitons in MEH-PPV solution below the critical temperature of the phase transition using steady-state photoluminescence measurements and pump-probe fs-spectroscopy at different temperatures. Spectral analysis indicates the coexistence of disordered chromophores with highly planarized chromophores.

Quantum control spectroscopy of competing reaction pathways in a molecular switch.

Excitation with shaped femtosecond laser pulses is a logical extension of coherent two-dimensional (2D) spectroscopy. Here we combine quantum control and information from 2D spectroscopy to analyze the initial steps in three competing reaction pathways of an isomerizing merocyanine dye. Besides the achievement of control objectives, we show how excitation with tailored pulses can be used to retrieve photochemical information that is inaccessible or experimentally demanding to obtain with other approaches.

A cascade through spin states in the ultrafast haem relaxation of met-myoglobin.

We report on a study of the early relaxation processes of met-Myoglobin in aqueous solution, using a combination of ultrafast broadband fluorescence detection and transient absorption with a broad UV-visible continuum probe at different pump energies. Reconstruction of the spectra of the transient species unravels the details of the haem photocycle in the absence of photolysis. Besides identifying a branching in the ultrafast relaxation of the haem, we show clear evidence for an electronic character of the intermediates, contrary to the commonly accepted idea that the early time relaxation of the haem is only due to cooling.

Ultrafast tryptophan-to-heme electron transfer in myoglobins revealed by UV 2D spectroscopy.

Tryptophan is commonly used to study protein structure and dynamics, such as protein folding, as a donor in fluorescence resonant energy transfer (FRET) studies. By using ultra-broadband ultrafast two-dimensional (2D) spectroscopy in the ultraviolet (UV) and transient absorption in the visible range, we have disentangled the excited state decay pathways of the tryptophan amino acid residues in ferric myoglobins (MbCN and metMb). Whereas the more distant tryptophan (Trp(7)) relaxes by energy transfer to the heme, Trp(14) excitation predominantly decays by electron transfer to the heme.

Peripheral microvascular dysfunction as an independent predictor of atherosclerotic damage in type 1 diabetes patients: a preliminary study.

It has been recently hypothesized that peripheral microvascular dysfunction may contribute to atherosclerotic damage (AD) in diabetic patients. In order to test this hypothesis, we assessed forearm skin post-occlusive reactive hyperaemia (skin-PORH), an index of peripheral microvascular function, using laser-Doppler flowmetry, in 40 type 1 diabetes patients (T1D-pts), aged 49 ± 11 years, with no known cardiovascular complications, and in 50 age and sex-matched healthy control subjects (CS). T1D-pts also underwent carotid arteries ultrasound scanning (Ca-US) and ankle-brachial index (ABI) measurement.

Study of skin vasomotion in type 1 diabetic patients and of its possible relationship with clinical and laboratory variables.

Vascular oscillation (vasomotion) occurs in the microcirculation and is thought to be a significant contributor to tissue perfusion. Our aim was to assess skin vasomotion (SV) of type 1 diabetic patients (T1D-pts) and its relationship with clinical or laboratory variables of the studied T1D-pts. Forearm endothelial-, sympathetic- and myogenic-dependent SV were assessed basally and after 3 min of forearm ischemia in 40 T1D-pts and 50 healthy controls, by spectral analysis of laser-Doppler (LD) signal at the frequency ranges of 0.

Femtosecond pump/supercontinuum-probe setup with 20 kHz repetition rate.

We developed a fast multichannel detection system for pump-probe spectroscopy, capable of detecting single shot super-continuum spectra at the repetition rate (10-50 kHz) of an amplified femtosecond laser system. By tandem pumping the amplifier with three pump lasers we obtain very low noise operation, with less than 0.1% rms intensity fluctuations at the output of the amplifier.

Ultrabroadband femtosecond two-dimensional ultraviolet transient absorption.

We present a broadband two-dimensional transient absorption setup for the UV around 300 nm with a time resolution of 150 fs. A narrowband, frequency tunable pump pulse and a broadband probe pulse are generated from the output of a noncollinear optical parametric amplifier operated at 20 kHz repetition rate and combined in a spectrally resolved transient absorption experiment. The high repetition rate and low noise of the setup allow us to acquire high quality two-dimensional data as a function of time delay with an unsurpassed frequency window of 10,000 and 8000  cm(-1) along the probe and pump axis, respectively.

Ultrafast (bio)physical and (bio)chemical dynamics.

We give an overview of our recent work on ultrafast dynamics of chemical (organic dyes, metal-complexes, colloidal quantum dots), and biological (retinal and haem proteins) systems in the liquid phase, studied with a variety of ultrafast optical techniques from the infrared to the ultraviolet.

Femtosecond UV studies of the electronic relaxation processes in Cytochrome c.

We report on an experimental study with UV and visible ultrafast time-gated emission and transient absorption of the early photodynamics of horse heart Cytochrome c in both ferric and ferrous redox states. A clear separation in time and energy of tryptophan and haem emission is observed. Excitation of the haem via resonant energy transfer from the tryptophan residue is observed in the subsequent haem electronic relaxation.

Ultrafast excited-state dynamics of rhenium(I) photosensitizers [Re(Cl)(CO)3(N,N)] and [Re(imidazole)(CO)3(N,N)]+: diimine effects.

Femto- to picosecond excited-state dynamics of the complexes [Re(L)(CO)(3)(N,N)](n) (N,N = bpy, phen, 4,7-dimethyl-phen (dmp); L = Cl, n = 0; L = imidazole, n = 1+) were investigated using fluorescence up-conversion, transient absorption in the 650-285 nm range (using broad-band UV probe pulses around 300 nm) and picosecond time-resolved IR (TRIR) spectroscopy in the region of CO stretching vibrations. Optically populated singlet charge-transfer (CT) state(s) undergo femtosecond intersystem crossing to at least two hot triplet states with a rate that is faster in Cl (∼100 fs)(-1) than in imidazole (∼150 fs)(-1) complexes but essentially independent of the N,N ligand. TRIR spectra indicate the presence of two long-lived triplet states that are populated simultaneously and equilibrate in a few picoseconds.

Exploring leukocyte mitochondrial membrane potential in type 1 diabetes families.

Proper cellular function requires the maintenance of mitochondrial membrane potential (MMP) sustained by the electron transport chain. Mitochondrial dysfunction is believed to play a role in the development of diabetes and diabetic complications possibly because of the active generation of free radicals. Since MMP can be investigated in clinical settings using fluorescent probes and living whole blood cells, mitochondrial membrane alterations have been observed in some chronic disorders.

Circadian blood pressure variability in type 1 diabetes subjects and their nondiabetic siblings - influence of erythrocyte electron transfer.

Background: Normotensive non-diabetic relatives of type 1 diabetes (T1D) patients have an abnormal blood pressure response to exercise testing that is associated with indices of metabolic syndrome and increased oxidative stress. The primary aim of this study was to investigate the circadian variability of blood pressure and the ambulatory arterial stiffness index (AASI) in healthy siblings of T1D patients vs healthy control subjects who had no first-degree relative with T1D. Secondary aims of the study were to explore the influence of both cardiovascular autonomic function and erythrocyte electron transfer activity as oxidative marker on the ambulatory blood pressure profile.

Inflammatory pattern in hemodiafiltration.

Chronic inflammation may play an important role in early morbidity and mortality in hemodialysis (HD) patients. Interleukin-6 (IL-6) production is enhanced in long-term HD patients and this activated phase response has been shown to be a predictor of cardiovascular disease in the uremic syndrome as well as in the general population. Furthermore, IL-6 and C-reactive protein (CRP) have been negatively related to low serum albumin levels (MIA syndrome).

The Pisa experience of renal biopsies, 1977-2005.

Introduction: Although several registries collecting data of patients with kidney diseases exist, only a few specifically collect data relating to renal biopsy. Kidney biopsy has been performed routinely in Pisa since 1977; the aim of this study was to report the relative frequency of nephropathies according to gender, age at time of biopsy, clinical presentation and renal function, based on histological diagnoses during the years 1977 through 2005. During this time, 3,810 kidney biopsies were performed, of which 89.