Correlated optical and electrical analyses of inhomogeneous core/shell InGaN/GaN nanowire light emitting diodes.

The performance of core-shell InGaN/GaN nanowire (NW) light emitting diodes (LEDs) can be limited by wire-to-wire electrical inhomogeneities. Here we investigate an array of core-shell InGaN/GaN NWs which are morphologically identical, but present electrical dissimilarities in order to understand how the nanoscale phenomena observed in individual NWs affect the working performance of the whole array. The LED shows a low number of NWs (∼20%) producing electroluminescence under operating conditions. This is related to a presence of a potential barrier at the interface between the NW core and the radially grown n-doped layer, which differently affects the electrical properties of the NWs although they are morphologically identical. The impact of the potential barrier on the performance of the NW array is investigated by correlating multi-scanning techniques, namely electron beam induced current microscopy, electroluminescence mapping and cathodoluminescence analysis. It is found that the main cause of inhomogeneity in the array is related to a non-optimized charge injection into the active region, which can be overcome by changing the contact architecture so that the electrons become injected directly in the n-doped underlayer. The LED with so-called 'front-n-contacting' is developed leading to an increase of the yield of emitting NWs from 20% to 65%.

Warm afterglow from the Toarcian Oceanic Anoxic Event drives the success of deep-adapted brachiopods.

Many aspects of the supposed hyperthermal Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic, c. 182 Ma) are well understood but a lack of robust palaeotemperature data severely limits reconstruction of the processes that drove the T-OAE and associated environmental and biotic changes. New oxygen isotope data from calcite shells of the benthic fauna suggest that bottom water temperatures in the western Tethys were elevated by c. 3.5 °C through the entire T-OAE. Modelling supports the idea that widespread marine anoxia was induced by a greenhouse-driven weathering pulse, and is compatible with the OAE duration being extended by limitation of the global silicate weathering flux. In the western Tethys Ocean, the later part of the T-OAE is characterized by abundant occurrences of the brachiopod Soaresirhynchia, which exhibits characteristics of slow-growing, deep sea brachiopods. The unlikely success of Soaresirhynchia in a hyperthermal event is attributed here to low metabolic rate, which put it at an advantage over other species from shallow epicontinental environments with higher metabolic demand.

Pulse Oximeter Usefulness for Blood Pressure Monitoring in Patients Implanted With Latest-Generation Continuous-Flow Device HeartMate 3.

INTRODUCTION: The measurement of blood pressure (BP) and the management of hypertension in patients with continuous-flow ventricular assist devices (CF-VADs) can present unique challenges. Patients with CF-VADs often do not have a palpable pulse, and therefore traditional blood pressure measurement by auscultation or automated cuff is less reliable. We tested the efficacy of blood pressure estimation using sphygmomanometry combined with finger pulse oximetry only after a hemodynamic optimization was effected to make the values estimated approximately similar to mean arterial pressure. METHODS: Fifteen consecutive patients with a mean age of 57.8 ± 11.2 years were implanted with HeartMate 3 between November 2015 and March 2017. All patients underwent pump speed optimization by conducting a ramp test during right heart catheterization. The patients were prospectively studied during the follow-up period and mean arterial pressure was estimated using 3 different methodologies: Doppler ultrasound, pulse oximeter, and automated blood pressure cuff. For each method 3 consecutive evaluations were conducted during 3 follow-up visits. RESULTS: For each patient, 9 different evaluations were obtained (3 for each method). The overall success rate was 100% for blood pressure assessment conducted with Doppler ultrasound and pulse oximeter and 80%-87% for automated monitor evaluations. The first 2 methodologies were 100% successful, while the third was 60% successful. Pearson's correlation analyses for the Doppler ultrasound and pulse oximeter measurements showed a good correlation when evaluations conducted with the same method were compared. A high variability emerged between estimations obtained by using an automated monitor and a poor correlation was found when this method was compared to the Doppler ultrasound and pulse oximeter measurements. CONCLUSION: According to our results, the pulse oximeter method showed a high success rate and a good correlation level with the standard procedure. Our data encourage the use of oximeters for domiciliary blood pressure assessment in patients implanted with a continuous flow device.

Pump Speed Optimization in Patients Implanted With the HeartMate 3 Device.

BACKGROUND: Pump speed optimization in patients implanted with a ventricular assist device represents a major challenge during the follow-up period. We present our findings on whether combined invasive hemodynamic ramp tests and cardiopulmonary exercise testing (CPX) can help optimize patient management. METHODS: Eighteen patients implanted with a HeartMate 3 (HM3) device underwent ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP], and blood pressure) and echocardiography. Data were recorded at up to 4 speed settings. Speed changes were in steps of 200 revolutions/min (rpm). Evaluation of functional capacity by CPX was conducted according to the modified Bruce protocol. RESULTS: Only 30% of patients had normal PCWPs at their original rpm settings. In going from lowest to highest speeds, cardiac output improved by 0.25 ± 0.35 L/min/step (total change, 1.28 ± 0.3 L/min), and PCWP decreased by 1.9 ± 0.73 mm Hg/step (total change, 6 ± 1.6 mm Hg). CVP and systolic blood pressure did not change significantly with rpm. The rpm assessment was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in all patients. On CPX, all patients demonstrated good performance (peak VO2, 16.8 ± 3.5 mL/kg/min). CONCLUSION: Hemodynamic ramp testing provides an objective means of optimizing rpm, and has the potential to provide good exercise tolerance.

Growth optimization and characterization of regular arrays of GaAs/AlGaAs core/shell nanowires for tandem solar cells on silicon.

With a band gap value of 1.7 eV, Al0.2Ga0.8As is one of the ideal III-V alloys for the development of nanowire-based Tandem Solar Cells on silicon. Nevertheless, growing self-catalysed AlGaAs nanowires on silicon by solid-source molecular beam epitaxy is a very difficult task due to the oxidation of Al adatoms by the SiO2 layer present on the surface. Here we propose a nanowire structure including a p.i.n radial junction inside an Al0.2Ga0.8As shell grown on a p-GaAs core. The crystalline structure of such self-catalysed nanowires grown on an epi-ready Si(111) substrate (with a thin native SiO2 layer) was investigated by transmission electronic microscopy and photoluminescence. I(V) measurements performed on single nanowires have shown a diode-like behaviour corresponding to the radial p.i.n junction inside the Al0.2Ga0.8As shell. Moreover, a current generation under the electron beam was evidenced over the entire radial junction along the nanowires by means of electron beam induced current (EBIC) microscopy. The same structure was reproduced on patterned substrates with a SiO2 mask, producing an ordered hexagonal array. High and uniform yields from 83% to 87% of vertical nanowires were obtained on 0.9 × 0.9 cm2 patterned areas. EBIC mapping performed on these nanowires confirmed the good electrical properties of the radial junction within the nanowires.

Ingestion and contact with polyethylene microplastics does not cause acute toxicity on marine zooplankton.

Toxicity of polyethylene microplastics (PE-MP) of size ranges similar to their natural food to zooplanktonic organisms representative of the main taxa present in marine plankton, including rotifers, copepods, bivalves, echinoderms and fish, was evaluated. Early life stages (ELS) were prioritized as testing models in order to maximize sensitivity. Treatments included particles spiked with benzophenone-3 (BP-3), a hydrophobic organic chemical used in cosmetics with direct input in coastal areas. Despite documented ingestion of both virgin and BP-3 spiked microplastics no acute toxicity was found at loads orders of magnitude above environmentally relevant concentrations on any of the invertebrate models. In fish tests some effects, including premature or reduced hatching, were observed after 12 d exposure at 10 mg L-1 of BP-3 spiked PE-MP. The results obtained do not support environmentally relevant risk of microplastics on marine zooplankton. Similar approaches testing more hydrophobic chemicals with higher acute toxicity are needed before these conclusions could be extended to other organic pollutants common in marine ecosystems. Therefore, the replacement of these polymers in consumer products must be carefully considered.

Size and specimen-dependent strategy for x-ray micro-ct and tem correlative analysis of nervous system samples.

Correlative approaches are a powerful tool in the investigation of biological samples, but require specific preparation procedures to maintain the strength of the employed methods. Here we report the optimization of the embedding protocol of nervous system samples for a correlative synchrotron X-ray computed microtomography (micro-CT) and transmission electron microscopy (TEM) approach. We demonstrate that it is possible to locate, with the micrometric resolution of micro-CT, specific volumes of interest for a further ultrastructural characterization to be performed with TEM. This approach can be applied to samples of different size and morphology up to several cm. Our optimized method represents an invaluable tool for investigating those pathologies in which microscopic alterations are localized in few confined regions, rather than diffused in entire tissues, organs or systems. We present a proof of concept of our method in a mouse model of Globoid Cells Leukodistrophy.

A large-field polarisation-resolved laser scanning microscope: applications to CARS imaging.

Laser-scanning imaging techniques are frequently used to probe the molecule spatial orientation in a sample of interest by exploiting selection rules depending on the polarisation of the excitation light. For the successful implementation of these techniques the precise control of the polarisation at the sample level is of fundamental importance. Polarisation distortions induced by the optical elements are often the main limitation factor for the maximum size of the field-of-view in polarisation-resolved (PR) laser-scanning microscopy, since for large scanning angles the polarisation distortions may mask the real sample structure. Here we shall demonstrate the implementation of large-field-of-view PR microscopy and show PR CARS imaging of mouse spinal cord thanks to a careful design of the laser-beam optical path. We shall show that this design leads to strongly suppressed distortions and quantify their effects on the final images. Although the focus of this work is on CARS imaging, we stress that the approaches described here can be successfully applied to a wide range of PR laser-scanning techniques.

Design and optimization of lipid-modified poly(amidoamine) dendrimer coated iron oxide nanoparticles as probes for biomedical applications.

Superparamagnetic iron oxide nanoparticles with a wide size range (2.6-14.1 nm) were synthesized and coated with the amphiphilic poly(amidoamine) PAMAM-C12 dendrimer. The resulting well dispersed and stable water suspensions were fully characterized in order to explore their possible use in biomedical applications. The structural and magnetic properties of the nanoparticles were preserved during the coating and were related to their relaxometric behaviour. The Nuclear Magnetic Resonance Dispersion (NMRD) profiles were found to be in accordance with the Roch model. The biocompatibility was assessed by means of cell viability tests and Transmission Electron Microscopy (TEM) analysis. The nanoparticles' capability of being detected via Magnetic Resonance Imaging (MRI) was investigated by means of clinical MRI scanners both in water and agar gel phantoms, and in a mouse model.

Ephyra jellyfish as a new model for ecotoxicological bioassays.

The aim of this study was a preliminary investigation on the possibility of using the ephyra of Scyphozoan jellyfish Aurelia aurita (Linnaeus, 1758), the common moon jellyfish, as an innovative model organism in marine ecotoxicology. A series of sequential experiments have been carried out in laboratory in order to investigate the influence of different culturing and methodological parameters (temperature, photoperiod, ephyrae density and age) on behavioural end-points (% of Frequency of Pulsations) and standardize a testing protocol. After that, the organisms have been exposed to two well known reference toxic compounds (Cadmium Nitrate and SDS) in order to analyse the acute and behavioural responses during static exposure. Results of this work indicate that the proposed behavioural end-point, frequency of pulsations (Fp), is an easily measurable one and can be used coupled with an acute one (immobilization) and that ephyrae of jellyfish are very promising model organisms for ecotoxicological investigation.

Energy balance in haemodialysis and peritoneal dialysis patients assessed by a 7-day weighed food diary and a portable armband device.

BACKGROUND: Energy balance (EB) is important when assessing nutritional status. EB has never been assessed in haemodialysis (HD) and peritoneal dialysis (PD) patients. The present study aimed to assess weekly EB in these patients. METHODS: This clinical cross-sectional study was conducted for 7 days in eight HD and eight PD patients. Nutritional status was assessed by anthropometry, bioelectrical impedance analysis and biochemical markers. Energy intake (EI per day) and total energy expenditure (TEE per day) were determined by a 7-day weighed food diary and a portable armband device, respectively. RESULTS: No significant differences in age, body mass index, fat free mass (FFM), parathyroid hormone were found between the two groups. EB was calculated by subtracting TEE per day from EI per day. EB was negative in HD {-1347 (1276) kJ day(-1) [-322 (305) kcal day(-1) ]}, as well as in PD patients {-427 (5338) kJ day(-1) [-102 (395) kcal day(-1) ]}. TEE per day was positively correlated with EI per day, prealbumin, FFM. EI per day was positively correlated with prealbumin. C-reactive protein was negatively correlated with TEE and FFM (P < 0.05). EB showed a positive correlation with EI per day (P = 0.012) and a negative trend with TEE. CONCLUSIONS: HD and PD patients have a negative EB and are at risk of malnutrition. Inflammatory status determines a lower EI per day and a reduction in TEE per day. The most important parameter in determining EB in HD and PD patients is EI per day. This topic deserves further investigation to better understand the mechanisms of impaired EB with respect to preserving patients' nutritional status.

Settlement of the alien mollusc Brachidontes pharaonis in a Mediterranean industrial plant: bioassays for antifouling treatment optimization and management.

In this work, we investigated the efficacy of three new biocides (77351, 73532, 73503--NALCO®) as specific antifouling products against adult organisms of the bivalve Brachidontes pharaonis (Fischer P., 1870), a Lessepsian species introduced in the Mediterranean Sea by sea transport (ballast water), and which has recently shown invasive behaviour in an industrial plant in Southern Italy (Sicily). These biocides were tested to verify their efficacy, as well as their environmental compatibility at discharge point, using the crustacean belonging to the genus Artemia (Leach, 1819) as model organism, according to Government Decree (D. Lgs) No. 152/06. Biocides were also tested using alternative crustaceans, Amphibalanus amphitrite (Darwin, 1854), and Tigriopus fulvus (Fischer, 1860), in order to check whether their introduction as model species in the national regulation could affect discharge limit concentrations (DLC) due to their different sensitivity, with likely economic and technical repercussions in the industrial water treatment sector.

Coherent detection of electron dephasing.

We show that an Aharonov-Bohm ring with asymmetric electron injection can act as a coherent detector of electron dephasing. The presence of a dephasing source in one of the two arms of a moderately-to-highly asymmetric ring changes the response of the system from total reflection to complete transmission while preserving the coherence of the electrons propagating from the ring, even for strong dephasing. We interpret this phenomenon as an implementation of an interaction-free measurement.

Differential near-field scanning optical microscopy with THz quantum cascade laser sources.

We have realized a differential Near-field Scanning Optical Microscope (NSOM) working with subwavelength resolution in the THz spectral region. The system employs a quantum cascade laser emitting at lambda approximately 105 microm as source, and the method, differently from conventional NSOM, involves diffracting apertures with size comparable to the wavelength. This concept ensures a higher signal-to-noise level at the expense of an additional computational step. In the implementation here reported lambda/10 resolution has been achieved; present limiting factors are investigated through finite difference time domain simulations.

Estimation of biogas produced by the landfill of Palermo, applying a Gaussian model.

In this work, a procedure is suggested to assess the rate of biogas emitted by the Bellolampo landfill (Palermo, Italy), starting from the data acquired by two of the stations for monitoring meteorological parameters and polluting gases. The data used refer to the period November 2005-July 2006. The methane concentration, measured in the CEP suburb of Palermo, has been analysed together with the meteorological data collected by the station situated inside the landfill area. In the present study, the methane has been chosen as a tracer of the atmospheric pollutants produced by the dump. The data used for assessing the biogas emission refer to night time periods characterized by weak wind blowing from the hill toward the city. The methane rate emitted by the Bellolampo dump has been evaluated using a Gaussian model and considering the landfill both as a single point source and as a multiple point one. The comparison of the results shows that for a first approximation it is sufficient to consider the landfill of Palermo as a single point source. Starting from the monthly percentage composition of the biogas, estimated for the study period, the rate of biogas produced by the dump was evaluated. The total biogas produced by the landfill, obtained as the sum of the emitted component and the recovered one, ranged from 7519.97 to 10,153.7m3/h. For the study period the average monthly estimations of biogas emissions into the atmosphere amount to about 60% of the total biogas produced by the landfill, a little higher than the one estimated by the company responsible for the biogas recovery plant at the landfill.

Trace element levels in adult patients with proteinuria.

AIM: Trace elements are involved in many metabolic processes. They circulate prevalently bound to protein. In literature few studies deal with metal metabolism in adult patients with proteinuria, so we decided to further investigate metal metabolism in proteinuric patients. METHODS: We studied 27 patients (14 male, 13 female), mean age 61.6+/-17 years with different degrees of renal function, serum albumin and proteinuria. Metal concentrations of copper (Cu), zinc (Zn) and aluminum (Al) were measured in serum and urine. No patient had environmental exposure to these metals. RESULTS: The serum Zn level was below the normal range in 11 patients. The serum Cu level was reduced in 5 patients. The Al serum level was elevated in 4 patients. Six patients had reduced and 6 patients had elevated Zn excretion. The urinary Cu excretion was elevated in 6 patients. The urinary Al excretion was elevated in 1 patient. Trace metal concentrations were related neither to renal function nor to total serum protein or albumin levels. Serum zinc was directly correlated with proteinuria and urinary zinc and negatively correlated with testosterone levels in both sexes. CONCLUSION: Adult patients with proteinuria have several modification of trace metal concentration in serum and urine. Serum concentration of metals did not depend on renal function or serum protein levels. Urinary Zn excretion was directly related to proteinuria and serum Zn levels. A negative correlation between serum Zn levels and testosterone was found in both sexes. Renal failure reduced urinary excretion of Cu and Al.

The optical visibility of graphene: interference colors of ultrathin graphite on SiO(2).

Monatomic layers of graphite are emerging as building blocks for novel optoelectronic devices. Experimental studies on a single graphite layer (graphene) are today possible since very thin graphite can be identified on a dielectric substrate using a normal optical microscope. We investigate the mechanism behind the strong visibility of graphite, and we discuss the importance of substrates and of the microscope objective used for the imaging.

Presence and distribution of serotonin immunoreactivity in the cyprids of the barnacle Balanus amphitrite.

In this work, the presence and distribution of serotonin in the cyprid of the barnacle Balanus amphitrite were investigated by immunohistochemical methods. Serotonin-like immuno-reactive neuronal cell bodies were detected in the central nervous system only. Various clusters of immunoreactive neuronal cell bodies are distributed in the brain (protocerebrum, deutocerebrum, optical lobes), and at least, four pairs of neuronal cell bodies were detected in the centrally positioned neuropil of the posterior ganglion. Rich plexuses of immunoreactive nerve fibers in the neuropil area were also observed. Furthermore, bundles of strongly immunoreactive nerve fibers surrounding the gut wall were localized, and immunoreactive nerve terminals in the antennules and compound eyes were observed. These data demonstrate the presence of a serotonin-like immunoreactive substance in the barnacle cyprids; furthermore, its immunolocalization in the cephalic nerve terminals allows us to postulate the involvement of this bioactive molecule in substrate recognition during the settlement process.

Functional analysis of R75Q mutation in the gene coding for Connexin 26 identified in a family with nonsyndromic hearing loss.

Mutations in the gene (GJB2) coding for Connexin 26 (Cx26) are responsible for genetic forms of sensorineural hearing loss. This article describes a family characterized by congenital profound hearing loss, inherited in an autosomal dominant fashion and associated to a R75Q substitution in Cx26. Cell transfection and fluorescence imaging, dye transfer experiments and dual patch clamp recording showed that the mutant completely prevents the formation of functional channels despite assembling into junctional plaques, in communication incompetent HeLa cells. The disease is not associated with palmar and plantar keratosis in any of the family members, suggesting that R75Q substitution is not sufficient for the development of the complete syndromic phenotype. The association of palmar and plantar keratosis with profound hearing loss may be dependent on genetic background, requiring a functional interaction between the mutated Cx26 and other epidermally expressed connexins.