Label- and Reagent-Free Optical Sensor for Absorption-Based Detection of Urea Concentration in Water Solutions.

Contactless and label-free detection of urea content in aqueous solutions is of great interest in chemical, biomedical, industrial, and automotive applications. In this work, we demonstrate a compact and low-cost instrumental configuration for label-free, reagent-free, and contactless detection of urea dissolved in water, which exploits the absorption properties of urea in the near-infrared wavelength region. The intensity of the radiation transmitted through the fluid under test, contained in a rectangle hollow glass tubing with an optical pathlength of 1 mm, is detected in two spectral bands. Two low-cost, low-power LEDs with emission spectra centered at λ = 1450 nm and λ = 2350 nm are used as readout sources. The photodetector is positioned on the other side of the tubing, in front of the LEDs. The detection performances of a photodiode and of a thermal optical power detector have been compared, exploiting different approaches for LED driving current modulation and photodetected signal processing. The implemented detection system has been tested on urea-water solutions with urea concentrations from 0 up to 525 mg/mL as well as on two samples of commercial diesel exhaust fluid ("AdBlue™"). Considering the transmitted intensity in presence of the urea-water solution, at λ = 1450 nm and λ = 2350 nm, normalized to the transmitted intensity in presence of water, we demonstrate that their ratio is linearly related to urea concentration on a wide range and with good sensitivity.

Optical Multi-Parameter Measuring System for Fluid and Air Bubble Recognition.

Detection of air bubbles in fluidic channels plays a fundamental role in all that medical equipment where liquids flow inside patients' blood vessels or bodies. In this work, we propose a multi-parameter sensing system for simultaneous recognition of the fluid, on the basis of its refractive index and of the air bubble transit. The selected optofluidic platform has been designed and studied to be integrated into automatic pumps for the administration of commercial liquid. The sensor includes a laser beam that crosses twice a plastic cuvette, provided with a back mirror, and a position-sensitive detector. The identification of fluids is carried out by measuring the displacement of the output beam on the detector active surface and the detection of single air bubbles can be performed with the same instrumental scheme, exploiting a specific signal analysis. When a bubble, traveling along the cuvette, crosses the readout light beam, radiation is strongly scattered and a characteristic fingerprint shape of the photo-detected signals versus time is clearly observed. Experimental testing proves that air bubbles can be successfully detected and counted. Their traveling speed can be estimated while simultaneously monitoring the refractive index of the fluid.

Design and Implementation of a Dual-Region Self-Referencing Fiber-Optic Surface Plasmon Resonance Biosensor.

The need for self-referencing is extremely important in the field of biosensing. In this manuscript, we report on the study, design, and validation of a dual-region self-referencing fiber-optic surface plasmon resonance biosensor. One region is intended to measure and monitor the binding events of the biological sample under test, while the other one is designed to be used as a reference channel to compensate for external factors, such as bulk refractive index modifications and temperature oscillations, that can negatively affect the biomolecular interaction measurement. Two different configurations for the biosensor probe are presented and investigated here, both theoretically and experimentally. First, the theoretical performance of the proposed biosensor probes, in terms of surface plasmon resonance wavelength shift, was simulated using a numerical model. Afterward, they were experimentally validated in sucrose-water solutions and showed a response to refractive index and temperature changes with sensitivities up to 2000 nm/RIU and 1.559 nm/°C, respectively. Finally, an aptamer-based bioassay and a high-resolution melting assay were successfully implemented on the two proposed configurations, demonstrating the feasibility of analyzing the binding events and measuring other external signal modifications simultaneously using the same biosensor probe.

Optical Identification of Parenteral Nutrition Solutions Exploiting Refractive Index Sensing.

Parenteral artificial nutrition (PAN) is a lifesaving treatment for a large population of patients affected by different diseases, and it consists of intravenous injection of nutritive fluids by means of infusion pumps. Wrong PAN solutions are, unfortunately, often administered, thus threatening the patients' well-being. Here, we report an optofluidic label-free sensor that can distinguish PAN solutions on the basis of their volumetric refractive index (RI). In our system, a monochromatic light beam, generated by a laser diode, travels obliquely through a transparent, square-section polystyrene channel, is then back-reflected by a mirror, and finally exits the channel in a position that depends on the filling fluid RI. The displacement of the output light spot ΔXexperim is easily detected with a linear, 1-D position sensitive detector (PSD). We initially calibrated the sensor with water-glucose solutions demonstrating a sensitivity S = ΔXexperim/Δn = 13,960 µm/RIU. We then clearly distinguished six commercial PAN solutions, commonly administered to patients. To the best of our knowledge, this is the first reported healthcare sensing platform for remote contactless recognition of PAN fluids, which could be inserted into infusion pumps to improve treatment safety, by checking the compliance to the prescription of the fluid actually delivered to the patient.

Clinical and psychopathological correlates of duration of untreated illness (DUI) in affective spectrum disorders.

Affective disorders represent psychopathological entities lying on a continuum, characterized by high prevalence and functional impairment. A delay in treatment initiation might increase the burden associated with affective spectrum disorders. The present study was aimed at analyzing the correlates of a long duration of untreated illness (DUI) in these conditions. We recruited subjects diagnosed with affective disorders, both in- and outpatients, and collected information concerning socio-demographic, clinical, and psychopathological characteristics. Long DUI was defined according to previous research criteria as >2 years for Bipolar Disorders or >1 year for Depressive Disorders. Bivariate analyses were performed to compare subjects with a long and short DUI (p<0.05). A logistic regression was operated to evaluate the correlates of long DUI. In the present sample (n=135), 34.1% (n=46) subjects showed a long DUI. This subgroup presented with more physical comorbidities (p=0.003), higher body mass index (BMI) (p<0.001), more frequent anxiety onset (p=0.018), younger onset age (p=0.042), and more severe depressive symptoms (Hamilton Depression Rating Scale item 1-depressed mood (p=0.032) and item 2-guilt feelings (p=0.018)). At the logistic regression, higher severity of depressed mood (OR 1.568), higher BMI (OR 1.264), and younger age at onset (OR 0.935) were associated with long DUI. The present study confirmed a possible role of DUI as a construct underpinning higher clinical severity in affective spectrum disorders, possibly linked to worse illness course and unfavorable outcomes. Intervention strategies targeting physical comorbidities and depressive symptoms severity may decrease disease burden in subjects with a long DUI.

Spectral Fingerprint Investigation in the near Infra-Red to Distinguish Harmful Ethylene Glycol from Isopropanol in a Microchannel.

Ethylene glycol (EG) and isopropanol (ISO) are among the major toxic alcohols that pose a risk to human health. However, it is important to distinguish them, since EG is more prone to cause renal failure, and can thus be more dangerous when ingested than ISO. Analysis of alcohols such as isopropanol and ethylene glycol generally can be performed with a complex chromatographic method. Here, we present an optical method based on absorption spectroscopy, performed remotely on EG-ISO mixtures filling a microchannel. Mixtures of ethylene glycol in isopropanol at different volume concentrations were analyzed in a contactless manner in a rectangular-section glass micro-capillary provided with integrated reflectors. Fiber-coupled broadband light in the wavelength range 1.3-1.7 µm crossed the microchannel multiple times before being directed towards an optical spectrum analyzer. The induced zig-zag path increased the fluid-light interaction length and enhanced the effect of optical absorption. A sophisticated theoretical model was developed and the results of our simulations were in very good agreement with the results of the experimental spectral measurements. Moreover, from the acquired data, we retrieved a responsivity parameter, defined as power ratio at two wavelengths, that is linearly related to the EG concentration in the alcoholic mixtures.

Spectral Phase Shift Interferometry for Refractive Index Monitoring in Micro-Capillaries.

In this work, we demonstrate spectral phase-shift interferometry operating in the near-infrared wavelength range for refractive index (RI) monitoring of fluidic samples in micro-capillaries. A detailed theoretical model was developed to calculate the phase-sensitive spectral reflectivity when low-cost rectangular glass micro-capillaries, filled with samples with different refractive indices, are placed at the end of the measurment arm of a Michelson interferometer. From the phase-sensitive spectral reflectivity, we recovered the cosine-shaped interferometric signal as a function of the wavelength, as well as its dependence on the sample RI. Using the readout radiation provided by a 40-nm wideband light source with a flat emission spectrum centered at 1.55 µm and a 2 × 1 fiberoptic coupler on the common input-output optical path, experimental results were found to be in good agreement with the expected theoretical behavior. The shift of the micro-capillary optical resonances, induced by RI variations in the filling fluids (comparing saline solution with respect to distilled water, and isopropanol with respect to ethanol) were clearly detected by monitoring the positions of steep phase jumps in the cosine-shaped interferometric signal recorded as a function of the wavelength. By adding a few optical components to the instrumental configuration previously demonstrated for the spectral amplitude detection of resonances, we achieved phase-sensitive detection of the wavelength positions of the resonances as a function of the filling fluid RI. The main advantage consists of recovering RI variations by detecting the wavelength shift of "sharp peaks", with any amplitude above a threshold in the interferometric signal derivative, instead of "wide minima" in the reflected power spectra, which are more easily affected by uncertainties due to amplitude fluctuations.

Micro-opto-fluidic platform for solvents identification based on absorption properties in the NIR region.

Spectral detection of light transmission through capillaries filled with a fluid sample is a powerful solution for evaluating its composition. In this work, we present an optical method to distinguish water and alcohol samples in a rectangular glass micro-capillary, coupled to an external fluidic path and laid flat onto an aluminum bulk mirror, from the spectral transmittance in the near-infra-red (NIR) wavelength range 1.15-1.65 µm, which becomes sample-specific thanks to the contribution given by the spectral absorption properties of the fluid. The readout beam of broadband radiation is shone on the upper flat side of the micro-capillary with an incidence angle of 14°, crosses the glass walls and the channel depth twice, since it is reflected by the mirror, and it is then coupled to the monochromator input of an optical spectrum analyzer. The theoretical transmission spectra of the capillary filled just with air as well as with distilled water, isopropanol, ethylene glycol, and 95% ethanol (with 5% water content) are derived using analytical equations including the wavelength-dependent attenuation due to fluid absorption. Experimental results relative to the wavelength dependence of the ratio between the spectral transmittance in the presence of the fluid sample and of just air are found to be in agreement with the calculated theoretical behavior. Grapical abstract.

Circadian rhythms disruptions and eating disorders: clinical impact and possible psychopathological correlates.

BACKGROUND: A link between abnormalities in circadian rhythms and the development of eating disorders was extensively hypothesized, mainly in consideration of the influence of the circadian clock on eating behavior. The present review is aimed at summarizing the evidence about biological rhythms disruptions in eating disorders, possibly clarifying their impact on the psychopathological profile of such patients. METHODS: Electronic database MEDLINE/PubMed/Index Medicus was systematically searched for original articles examining the prevalence of circadian rhythms disruptions in eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder). RESULTS: Studies included in the review confirmed the hypothesis of a high prevalence of circadian disruptions in eating disorders. The analyzed research mainly focused on sleep-wake cycle, rest-activity abnormalities and hormonal secretion, whilst literature about other circadian rhythms was scanty. Altered biological rhythms presented higher association with specific psychopathological features, but such relationship was assessed in few studies. CONCLUSIONS: Circadian rhythms disruptions were confirmed to be relevant aspects in the context of eating disorders. Further research is needed in order to clarify the role of biological rhythms in such illnesses, in the attempt to address adjunctive treatment strategies with the possible focus of circadian abnormalities.

A VCSEL-Based NIR Transillumination System for Morpho-Functional Imaging.

Transillumination with non-ionizing radiation followed by the observation of transmitted and diffused light is the simplest, and probably the oldest method to obtain qualitative information on the internal structure of tissues or body sections. Although scattering precludes formation of high-definition image (unless complex techniques are employed), low resolution pictures complemented by information on the functional condition of the living sample can be extracted. In this context, we have investigated a portable optoelectronic instrumental configuration for efficient transillumination and image detection, even in ambient day-light, of in vivo samples with thickness up to 5 cm, sufficient for visualizing macroscopic structures. Tissue illumination is obtained with an extended source consisting in a matrix of 36 near infrared Vertical Cavity Surface Emitting Lasers (VCSELs) that is powered by a custom designed low-voltage current driver. In addition to the successful acquisition of morphological images of the hand dorsal vein pattern, functional detection of physiological parameters (breath and hearth rate) is achieved non-invasively by means of a monochrome camera, with a Complementary Metal Oxide Semiconductor (CMOS) sensor, turned into a wavelength selective image detector using narrow-band optical filtering.

Spectral Optical Readout of Rectangular-Miniature Hollow Glass Tubing for Refractive Index Sensing.

For answering the growing demand of innovative micro-fluidic devices able to measure the refractive index of samples in extremely low volumes, this paper presents an overview of the performances of a micro-opto-fluidic sensing platform that employs rectangular, miniature hollow glass tubings. The operating principle is described by showing the analytical model of the tubing, obtained as superposition of different optical cavities, and the optical readout method based on spectral reflectivity detection. We have analyzed, in particular, the theoretical and experimental optical features of rectangular tubings with asymmetrical geometry, thus with channel depth larger than the thickness of the glass walls, though all of them in the range of a few tens of micrometers. The origins of the complex line-shape of the spectral response in reflection, due to the different cavities formed by the tubing flat walls and channel, have been investigated using a Fourier transform analysis. The implemented instrumental configuration, based on standard telecom fiberoptic components and a semiconductor broadband optical source emitting in the near infrared wavelength region centered at 1.55 µm, has allowed acquisition of reflectivity spectra for experimental verification of the expected theoretical behavior. We have achieved detection of refractive index variations related to the change of concentration of glucose-water solutions flowing through the tubing by monitoring the spectral shift of the optical resonances.

Flow-through micro-capillary refractive index sensor based on T/R spectral shift monitoring.

We present a flow-through refractive index sensor for measuring the concentration of glucose solutions based on the application of rectangular glass micro-capillaries, with channel depth of 50 µm and 30 µm. A custom designed and 3D printed polymeric shell protects the tiny capillaries, ensuring an easier handling and interconnection with the macro-fluidic path. By illuminating the capillary with broadband radiation centered at λ~1.55 µm, both the transmitted (T) and reflected (R) optical spectrum from the capillary are detected with an optical spectrum analyzer, exploiting an all-fiber setup. Monitoring the spectral shift of the ratio T/R in response to increasing concentration of glucose solutions in water we have obtained sensitivities up to 530.9 nm/RIU and limit of detection in the range of 10-5-10-4 RIU. Experimental results are in agreement with the theoretically predicted principle of operation. After the demonstration of amplitude detection at a single wavelength, we finally discuss the impact of the capillary parameters on the sensitivity.

Oral versus long-acting injectable antipsychotics: hospitalisation rate of psychotic patients discharged from an Italian Psychiatric Unit.

OBJECTIVE: The primary aim is to verify the efficacy of long-acting injectable (LAI) and oral antipsychotics (AP) in terms of re-hospitalisation rate of patients with psychotic disorders. The second aim is to evaluate socio-demographic and clinical differences in patients that were re-hospitalised after the index discharge compared to patients that were not re-hospitalised. Finally, socio-demographic and clinical differences of re-hospitalised patients that were prescribed at discharge with oral or LAI AP were analysed. METHODS: A retrospective observational study including all patients discharged with diagnosis of psychotic disorders from July 2011 to July 2013 was conducted. Patients discharged with LAI or with oral AP were included. Re-hospitalisations occurred during a follow-up period of 24 months after the index discharge were considered. Chi-square test or Student's t-test were used for comparisons. Odds ratios (OR) and 95% confidence intervals (CI) for the incidence of re-hospitalisation for LAI or oral AP were provided. RESULTS: No significant differences between LAI and oral AP in terms of re-hospitalisation rate in a 24-month period were found. Clinical and socio-demographic characteristics did not significantly differ between the groups. CONCLUSIONS: LAI seemed to be similar to oral AP in terms of prevention of re-hospitalisation in psychotic patients.

Psychopathological characteristics of patients with first-episode psychosis and chronic schizophrenia: a descriptive comparison.

Only few studies have compared the psychopathological features in first episode psychosis (FEP) and chronic schizophrenia (CS) patients. The aim of our study was to compare sociodemographic and clinical aspects of FEP and CS inpatients using the Positive and Negative Syndrome Scale (PANSS) and the Brief Psychiatric Rating Scale (BPRS) in order to better characterize FEP. We did not find significant socio-demographic differences between the two groups apart from age and nationality. About PANSS we found that conceptual disorganization, poor rapport and lack of insight items scores were significantly higher in patients with FEP. Related to BPRS the items of somatic concerns, grandiosity and motor hyperactivity were significantly higher in the CS group; uncooperativeness was significantly higher in FEP group. Our study offers a characterization of FEP patients that confirms evidence and adds some information from the current literature. FEP patients seem to be more uncooperative with a worse interpersonal empathy and insight into the illness than CS patients; this could reduce their compliance with the treatment.

Mesoporous silica sub-micron spheres as drug dissolution enhancers: Influence of drug and matrix chemistry on functionality and stability.

Mesoporous silica particles prepared through a simplified Stöber method and low temperature solvent promoted surfactant removal are evaluated as dissolution enhancers for poorly soluble compounds, using a powerful anticancer agent belonging to pyrroloquinolinones as a model for anticancer oral therapy, and anti-inflammatory ibuprofen as a reference compound. Mesoporous powders composed of either pure silica or silica modified with aminopropyl residues are produced. The influence of material composition and drug chemical properties on drug loading capability and dissolution enhancement are studied. The two types of particles display similar size, surface area, porosity, erodibility, drug loading capability and stability. An up to 50% w/w drug loading is reached, showing correlation between drug concentration in adsorption medium and content in the final powder. Upon immersion in simulating body fluids, immediate drug dissolution occurred, allowing acceptor solutions to reach concentrations equal to or greater than drug saturation limits. The matrix composition influenced drug solution maximal concentration, complementing the dissolution enhancement generated by a mesoporous structure. This effect was found to depend on both matrix and drug chemical properties allowing us to hypothesise general prediction behaviour rules.

Personality and psychotic symptoms as predictors of self-harm and attempted suicide.

BACKGROUND: Nonfatal suicidal behaviours (NSB), including suicide ideation, suicide plan and suicide attempt, constitute a serious problem for public healthcare services. Suicide gesture (SG) which refers to self-injurious behaviour with no intent to die, differs from NSB in a variety of important ways. The aim of this study was to investigate demographic and clinical characteristics of NSB and SG to examine whether self-injurers with intent to die differ significantly from self injurers without such intent. METHODS: All admissions for NSB and SG to the Psychiatric Inpatient Unit of University / General Hospital Santa Maria della Misericordia, Perugia, Umbria, Italy, from January 2015 to June 2015 were included in a medical record review. Basic descriptive statistics and distributional properties of all variables were first examined. Bivariate analyses were performed using Chi-square tests for group comparisons and t-test for independent samples used when appropriated. RESULTS: The study sample included 38 patients. Of these 23 had committed NSB (13.1%), 15 had commetted SG (8.5%). Number of married NSB was significantly higher than the number of married SG (p=0.08). We found a significant difference between NSB and SG related to the item of impulse control that was poorer in SG than NSB (p=0.010). BPRS items of hostility (p=0.082), suspiciousness (p=0.042) and excitement (p=0.02) were found to be significantly higher in SG than NSB. Borderline personality disorder (p=0.032) and Passive-Aggressive personality disorder (p=0,082) diagnosed by the means of the SCID-II, were more represented in SG than NSB (p=0.044). Schizoid personality disorder was significantly related to NSB (p=0.042). No others significant differences were found. CONCLUSIONS: NSB and SG are different for many psychopathological characteristics. These results confirm the importance of classifying individuals on the basis of the intent to die. Additional research is needed to understand and elucidate psychopatological and clinical characteristics of the different categories of self-injurers to find risk factors specific to suicide attempts.

Transmetallation as an effective strategy for the preparation of bimetallic CoPd and CuPd nanoparticles.

The preparation of palladium alloy nanoparticles is of great interest for many applications, especially in catalysis. Starting from presynthesized nanoparticles of a less noble metal, a transmetallation reaction involving a redox process at the nanoparticle surface can be exploited to modify the nanoparticle composition and crystalline phase. As an example, monodispersed ε-cobalt and face-centered cubic copper nanoparticles were synthesized in organic solvents at high temperature and the as-formed nanoparticles were reacted with palladium(ii) hexafluoroacetylacetonate resulting in the formation of alloyed nanoparticles whose composition closely follows the reactant ratio. The oxidative state of the nanoparticle surface greatly affects the success of the transmetallation reaction and a reduction treatment was necessary to achieve the desired final product. Electron microscopy and X-ray diffraction showed that for cobalt a limiting palladium content for the ε-phase alloy is found, above which an fcc alloy nucleates, while for copper the fcc crystalline phase is preserved throughout the whole composition range.

Ultrasmall iron oxide nanoparticles for biomedical applications: improving the colloidal and magnetic properties.

A considerable increase in the saturation magnetization, M(s) (40%), and initial susceptibility of ultrasmall (<5 nm) iron oxide nanoparticles prepared by laser pyrolysis was obtained through an optimized acid treatment. Moreover, a significant enhancement in the colloidal properties, such as smaller aggregate sizes in aqueous media and increased surface charge densities, was found after this chemical protocol. The results are consistent with a reduction in nanoparticle surface disorder induced by a dissolution-recrystallization mechanism.

Iridium/silicon multilayers for extreme ultraviolet applications in the 20-35 nm wavelength range.

We have developed an Ir/Si multilayer for extreme ultraviolet (EUV) applications. Normal incidence reflectance measurements of a prototype film tuned to 30 nm wavelength show superior performance relative to a conventional Mo/Si multilayer structure; we also find good stability over time. Transmission electron microscopy and electron dispersive x-ray spectroscopy have been used to examine the microstructure and interface properties of this system: we find amorphous Si layers and polycrystalline Ir layers, with asymmetric interlayer regions of mixed composition. Potential applications of Ir/Si multilayers include instrumentation for solar physics and laboratory EUV beam manipulation.

Femtosecond nonlinear absorption of gold nanoshells at surface plasmon resonance.

The nonlinear optical absorption of gold nanoshells (Au NSs) of different size, in water, was investigated using open aperture z-scan technique with femtosecond laser pulses at 806 nm. It is found that, in general, NSs behave as saturable absorbers. The level of saturation depends on the Au NSs structure and precisely on the ratio between the core size and shell thickness. The measured values of the nonlinear absorption coefficient show a dependence on both the repetition rate and the pulse energy. An average value of the nonlinear absorption coefficient ß = -4.5 ± 1.0 × 10(-11) cm W(-1) is obtained from z-scan data of core-shell particles of inner and outer radius 95 and 110 nm, respectively, measured at 20 Hz repetition rate in the energy range 120-300 nJ.