Over the past few years, sensors made from high-Z compound semiconductors have attracted quite some attention for use in applications which require the direct detection of X-rays in the energy range 30-100 keV. One of the candidate materials with promising properties is cadmium zinc telluride (CdZnTe). In the context of this article, we have developed pixelated sensors from CdZnTe crystals grown by Boron oxide encapsulated vertical Bridgman technique. We demonstrate the successful fabrication of CdZnTe pixel sensors with a fine pitch of 55 µm and thickness of 1 mm and 2 mm. The sensors were bonded on Timepix readout chips to evaluate their response to X-rays provided by conventional sources. Despite the issues related to single-chip fabrication procedure, reasonable uniformity was achieved along with low leakage current values at room temperature. In addition, the sensors show stable performance over time at moderate incoming fluxes, below 10 photons mm s .

Cadmium zinc telluride crystals of 4.8 cm in diameter grown by the boron oxide encapsulated vertical Bridgman technique exhibit good structural quality with large grains and low dislocation density. How- ever, the ingots contain Te inclusions, which are trapped at the growth interface during the crystallization process. Global modeling of the furnace was applied in order to investigate the temperature gradients and the evolution of the growth interface shape in this system. Transient computations, which include the crucible movement, show that the crystal-melt interface is concave toward the melt in the conical part of the ampoule, then becomes convex during the growth in the cylindrical part of the ampoule. Concave shapes of the interface and very homogeneous temperature distribution at the beginning of the solidification process promote the growth of a polycrystalline material. A novel hypothesis explaining the mechanism of grain formation at the ampoule tip was formulated. Our calculations show that the anoma- lous Zn segregation is due to the poor solute mixing at the beginning of the solidification process. The modeling of the standard growth process reveals very low vertical temperature gradients in the crys- tal (2-4 K/cm). Such low temperature gradients are not favorable to eliminate the Te inclusions in the as grown crystal. A numerical model was employed to analyze the temperature field influence on the migration/size reduction of Te inclusions.

We show nanoscale spectroscopy and mapping of plasmon-excition coupling in Au/ZnO nanostructure by STEM-EELS and STEM-CL. Interestingly, the Au plasmon resonance is localized at Au/vacuum interface, while the ZnO signal is localized inside Au nanoparticle.

Density is a very important property of materials because of its influence on their mechanical properties. For this reason, the possibility of measuring material density is of strategic importance for several industrial applications such as wood boards sawing, wood panels production, or ceramic tiles manufacturing. In order to answer to this need, X-ray densitometry techniques and computed tomography (CT) scanners are used nowadays. However, these traditional X-ray inspection techniques usually measure only relative density, or, in other terms, they need a calibration procedure before operation. To overcome this issue, Due2lab s.r.l. in collaboration with the Istituto dei Materiali per l'Elettronica ed il Magnetismo (IMEM)-Consiglio Nazionale delle Ricerche (CNR) Institute developed a CdZnTe (CZT)-based X-ray spectrometer capable of determining the absolute density value of a sample material in terms of g/cm 3 (and additionally extracting information about its elemental composition). The system has been specifically designed for in-line real-time nondestructive inspection of industrial production; thus, it is potentially capable to return density information within a very short acquisition time. In this article, we will describe the CZT spectrometer and the hyperspectral X-ray analysis set-up in detail and we will show how to perform absolute density measurement on three different materials: 1) a plastic polyethylene sample, 2) ceramic tiles, and 3) pine and fir wood samples.

Cadmium is toxic to humans, although Cd-based quantum dots exerts less toxicity. Human hepatocellular carcinoma cells (HepG2) and macrophages (THP-1) were exposed to ionic Cd, Cd(II), and cadmium sulfide quantum dots (CdS QDs), and cell viability, cell integrity, Cd accumulation, mitochondrial function and miRNome profile were evaluated. Cell-type and Cd form-specific responses were found: CdS QDs affected cell viability more in HepG2 than in THP-1; respective IC values were ~3 and ~50 ?g ml. In both cell types, Cd(II) exerted greater effects on viability. Mitochondrial membrane function in HepG2 cells was reduced 70 % with 40 ?g ml CdS QDs but was totally inhibited by Cd(II) at corresponding amounts. In THP-1 cells, CdS QDs has less effect on mitochondrial function; 50 ?g ml CdS QDs or equivalent Cd(II) caused 30 % reduction or total inhibition, respectively. The different in vitro effects of CdS QDs were unrelated to Cd uptake, which was greater in THP-1 cells. For both cell types, changes in the expression of miRNAs (miR-222, miR-181a, miR-142-3p, miR-15) were found with CdS QDs, which may be used as biomarkers of hazard nanomaterial exposure. The cell-specific miRNome profiles were indicative of a more conservative autophagic response in THP-1 and as apoptosis as in HepG2.

The data included in this paper are associated with a research article entitled 'Differences in toxicity, mitochondrial function and miRNome in human cells exposed in vitro to Cd as CdS quantum dots or ionic Cd' [1]. The article concerns the use of miRNAs as biomarkers for engineered nanomaterials (ENMs) risk assessment. Two different type of human cells, HepG2 and THP-1, were exposed to different forms of Cadmium: nanoscale, as CdS quantum dots (CdS QDs), and ionic, as CdSO 8/3 -hydrate (Cd(II)). The cells were treated with sub-toxic doses of CdS QDs; 3 µg ml in HepG2 and 6.4 µg ml and 50 µg ml in THP-1, as well as equivalent cadmium doses as Cd(II). In this dataset, changes in expression levels of miRNAs are reported. In addition, GO enrichment analyses of target genes of miRNAs modulated by Cd stress, network analysis of the microRNome and an in silico pathway analysis are also reported. These data enhance and also summarize much of the data independently presented in the research article and therefore, must be considered as supplementary.

The use of cadmium sulphide quantum dot (CdS QD)-enabled products has become increasingly widespread. The prospect of their release in the environment is raising concerns. Here we have used the yeast model Saccharomyces cerevisiae to determine the potential impact of CdS QD nanoparticles on living organisms. Proteomic analyses and cell viability assays performed after 9 h exposure revealed expression of proteins involved in oxidative stress and reduced lethality, respectively, whereas oxidative stress declined, and lethality increased after 24 h incubation in the presence of CdS QDs. Quantitative proteomics using the iTRAQ approach (isobaric tags for relative and absolute quantitation) revealed that key proteins involved in essential biological pathways were differentially regulated over the time course of the experiment. At 9 h, most of the glycolytic functions increased, and the abundance of the number of heat shock proteins increased. This contrasts with the situation at 24 h where glycolytic functions, some heat shock proteins as well as oxidative phosphorylation and ATP synthesis were down-regulated. It can be concluded from our data that cell exposure to CdS QDs provokes a metabolic shift from respiration to fermentation, comparable to the situation reported in some cancer cell lines.

Organic Electrochemical Transistor (OECTs) are devices that can measure the ionic content of liquid samples and biological systems. The response of an OECT can provide information on the physiological conditions and characteristics of a biological system. In a typical OECT configuration, the system or sample is connected to a reference electrode (the gate) and to a semiconducting material, typically PEDOT:PSS, with two other terminals (the drain and the source) for connection to an external circuit. The transistor architecture of OECTs enables signal control and amplification. Upon application of an external electromagnetic field at the electrodes, ions are driven from the liquid sample towards the PEDOT:PSS channel, where they modify the conductivity of the channel and generate a continuous current as a function of time. The intensity of that current and the time to the steady state can be correlated to the characteristics of the ions in solution. In most of the existing theories that model the behavior of OECTs, the internal configuration and geometrical parameters of the device are assumed to be constant over time. This simplifying assumption breaks down in living systems and in all those soft devices with elevated value of compliance and absorption (such as devices on paper, textile or polymeric sponges). Similar simplified models may fail to predict the behavior of real systems within acceptable bounds. Here, we present a mathematical model that describes the behavior of OECTs in which the geometry of the internal fluidic circuits of the system can change over time. These circuits represent the network of chambers and channels through which the liquid solution flows from the gate to the drain-source electrodes, enabling the transport of ions. At a certain time, the liquid solution shall be spread throughout a fraction only of the entire network available for liquid transport, i.e. the wet fraction p. The mathematical model that we have developed in this work uses the data generated by OECTs to determine the wet fraction p and the concentration C of ions of a system. The model enables quantification of a system without calibration of the device, which may be of interest for those working in the fields of bioengineering, biomedical sensors, wearable electronics, flexible electronics. In experiments where the variables of system were varied over large intervals, the model achieved an excellent performance and a precision up to 92%.

Detectors based on compound semiconductor materials like CdTe and CdZnTe are more susceptible to defect-related spectral distortions than elemental semiconductors like Si or Ge. During the design process of new detectors based on these materials it is crucial to consider the effect of these distortions on the detector performance. Due to the diverse range of application areas in which these detectors may be used, the detector geometry must be selected to match the desired application of the device. For those requiring the detection of photons across a broad energy range (1 - 1000 keV), the detector design must account for a variety of different interaction processes. The simulation framework presented in this paper includes all the physical processes involved in the formation of the detector signal, from the radiation absorption mechanisms to the influence of the electrode geometry. A simulation system based on first principle calculations is used which consists of a Monte Carlo simulator, a Finite Elements Method (FEM) calculator and numerical computation software. The framework simulates the radiation-semiconductor interaction, the charge carrier transport and the role of the electric field and weighting field in signal induction on the electrodes. This tool allows to simulate the entire experimental arrangement including the use of attenuators, collimators and scattering surfaces. The ability to accurately simulate the detector response to radiation and its surroundings provides a powerful tool for the realization of a new generation of detector systems. In order to validate the simulation framework, CdZnTe-based detectors with several contact geometries have been modelled and the output of the simulations have been compared to experimental data. A comparison between the simulated and measured responses demonstrate the power of this technique.

Textile organic electrochemical transistors (txOECTs) are a new class of wearable biosensors used to monitor physiological parameters in bio fluids of clinical interest. Herein the selectivity of a textile biosensor was improved directly functionalizing the textile device with ion selective membranes. The device was prepared by a series of consecutive functionalization of the textile fiber, first by applying the conductive polymer poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) and subsequently the ion selective membrane based on different ionophores with the aim of measuring electrolytes in sweat. The ion selective membranes were previously tested and optimized by potentiometric measurements. The biosensor devices were studied with different concentration of electrolytes. Membrane selectivity was tested comparing transistor response with interfering ions, proving successfully the selective response to sodium, potassium and calcium ions. The ability of the textile biosensors to discriminate among the cations was demonstrated over the 10-5 - 1 M concentration range, a concentration range found in sweat. The electronic parameters of the txOECTs show differences not only in modulation response but also in time constants of kinetic behavior. The selective determination of potassium and calcium in sweat has a great importance in different applications, for example, in human sweat monitoring, to understand physiological conditions, like dehydration, cardiac bioactivity and hypokalemia.

The differential mechanisms of CdS QDs (Quantum Dots) and Cd ion toxicity to Arabidopsis thaliana (L.) Heynh were investigated. Plants were exposed to 40 and 60 mg L"1 for CdS QDs and 76.9 and 115.2 mg L"1 CdSO4$7H2O and toxicity was evaluated at 5, 20, 35 (T5, T20, T35) days after exposure. Oxidative stress upon exposure was evaluated by biochemical essays targeting non-enzymatic oxidative stress physiological parameters, including respiration efficiency, total chlorophylls, carotenoids, ABTS and DPPH radicals reduction, total phenolics, GSH redox state, lipid peroxidation. Total Cd in plants was measured with AAS. Root and leaf morphology and element content were assessed in vivo utilizing lowvacuum Environmental Scanning Electron Microscopy (ESEM) with X-ray microanalysis (EDX). This integrated approach allowed identification of unique nanoscale CdS QDs toxicity to the plants that was distinct from CdSO4 exposure. The analyses highlighted that CdS QDs and Cd ions effects are modulated by the developmental stage of the plant, starting from T20 till T35 the plant development was modulated by the treatments, in particular CdS QDs induced early flowering. Both treatments induced Fe accumulation in roots, but at different intensities, while CdS QDs was associated with Mn increase into plant leaf. CdSO4 elicited higher levels of oxidative stress compared with QDs, especially the former treatment caused more intense respiration damages and reduction in chlorophyll and carotenoids than the latter. The two types of treatments impact differently on root and leaf morphology.

We report on the development and of a complete X/? rays detection system (10-1000 keV) based on CZT spectrometers with spatial resolution in three dimensions (3D) and a digital electronics acquisition chain. The prototype is made by packing four linear modules, each composed of one 3D CZT sensors. Each sensors is realized using a single spectroscopic graded CZT crystal of about 20×20×5 mm3. An electrode structure consisting of 12 collecting anodes with a pitch of 1.6 mm and 3 drift strips between each pair of anodes for 48 strips (0.15 mm wide) on the anodic side was adopted. The cathode is made of 10 strips with a pitch of 2 mm and orthogonal to anode side strips. Since the reading of the drift strips will carried out by putting in parallel all the strips that occupy the same place with respect to a collecting anode, the channels number for each sensors is only 25. The detector readout front-is based on custom designed low noise charge sensitive pre-amplifiers (CSP) implemented in hybrid 16 channels board. The CZT module and its CSP front-end provide the signals to a multichannel Digital Pulse Processing FPGA based system able to digitize and process continuously the signals. The digital system implement an innovative firmware that allow performing fine time-tagging, online pulse shape and height analysis with good energy resolution.

An innovative X-ray inspection technology, named XSpectra (R), has been developed with the aim to improve the current state of art in the field of real-time detection of contaminants in food products on production lines. The technology architecture is based on modules equipped with a 128 pixels CdTe array detector each read-out by full-custom Front-End ASICs. A full-custom Multi-Channel-Analyzer reconstructs the radiation spectrum, which is then processed by advanced Neural Network algorithms performing both image reconstruction and foreign bodies detection. The experimental characterization of XSpectra (R) has demonstrated the sensitivity of the fully operating system to photon energies down to about 10 keV at events rates up to several millions of photons per second. A line-width of 8.5 keV FWHM has been measured, at room temperature, on the 60 keV photo-peak of a synchrotron radiation in low-rate conditions. A spectral non-linearity error within +/- 0.5% has been obtained within the energy range 25 keV -100 keV. The effective capability of XSpectra (R) to detect currently undetectable low-density contaminants inside real food products has also been proved.

Organic electrochemical transistors (OECTs) are transducing devices that, placed in contact with an electrolyte solution, detect the ionic composition of that solution by measuring the channel current I. OECTs enable the streaming of continuously updated zero-to-low latency information and show, therefore, promise for being used as highly efficient biosensors. Nevertheless, apart from simple geometries, decoding such an information may be infeasible. Here, we show how I can be processed to derive a reduced set of two variables that account for most of the information of a system: 1) the modulation m is the current gained by the system compared to its initial value; and 2) the effective time t(e) is the time over which the response of the system stays above the 65% of its final value. m and t(e) can be reported in a diagram that is akin to the state space diagrams used in thermodynamics: points in the diagram describe the state of a system at a specific time; trajectories in the diagram describe the time evolution of that system. We show that the total electric charge Q exchanged by the system between two states A and B is independent on the path taken between them. This, in turn, implies that m and t(e) are state variables of the system. In experiments with Solanum lycopersicum tomato plants, we show how this concept can be used to extract relevant information about a biophysical system without direct knowledge of its internal workings.

Zinc oxide (ZnO) nanostructures can be grown in different morphologies by means of a wide range of techniques. Although the strong evidence of their gas sensing capabilities has been reported in several papers, not all of them are suitable for a large-scale or industrial scale production of gas sensor devices. Among the several ZnO nanostructures that have been grown so far at IMEM-CNR Institute, we focused our attention on tetrapods (TPs), because a vapour phase growth process that can produce grams of these nanostructures have been designed and optimized in our laboratories. This quantity of nanostructures, produced in a small lab-scale reactor, is enough to prepare several thousands of gas sensing devices. Moreover, the produced ZnO-TPs are free-standing and not constrained to a growth substrate, and can be easily suspended in a liquid media. The highly-porous entangled network of ZnO-TPs, which can be obtained by direct deposition on sensor substrate, demonstrated to efficiently work as chemoresistor, while its sensing properties (sensitivity, selectivity, ...) can be tuned or modified through the functionalization of TPs surface with other materials (noble metals, inorganic semiconductor nanoparticles, organic semiconductor layers). At the same time, ZnO nanostructures and their multifunctional properties can be used to functionalize the surface of other materials and, eventually, add to them sensing capabilities. As a meaningful example, we can illustrate the adding of ZnO nanorods (ZnO-NRs) to the surface of carbon fibers with a wet chemical process that is easily scalable to a larger scale. It has been recently demonstrated that two crossing ZnO-functionalized carbon fibers can be used to sense and transduce a piezoelectric signal or UV light, as well as a chemoresistive information.

A system for the remote detection of substances, comprising a vehicle that is mobile in space and remote-piloted using a control device with a haptic interface suitable to return a force feedback to a user of the control device, wherein the vehicle is equipped with a position sensor and a sensor for detecting a physical quantity whose intensity depends on the distance of at least one substance present in a detection point located in a vicinity of the position of the vehicle.

In order to maximise the absoprtion efficiency ofX-ray detectors for high energy photons above 20 keV, compound semiconductor sensors with high atomic number (Z) are under investigation. A promising material for future detector systems is Cadmium Zinc Telluride (CdZnTe). Redlen Technologies developed a novel CdZnTe material, optimised for applications with high photon fluxes. Such a material was used to fabricate pixelated CdZnTe sensors with a pitch of 55 ?m and 110 ?m. The sensors were flip-chip bonded to Timepix ASICs and their performance was characterised at the European Synchrotron Radiation Facility (ESRF) with conventional X-ray sources and monochromatic sychrotron beams using the MAXIPIX readout system. We present results concerning the uniformity, the stability and the spatial resolution of the sensors, obtained with X-ray energies up to 60 keV.

The aim of this work was to use the yeast Saccharomyces cerevisiae as a tool for toxicogenomic studies of Engineered Nanomaterials (ENMs) risk assessment, in particular focusing on cadmium based quantum dots (CdS QDs). This model has been exploited for its peculiar features: a short replication time, growth on both fermentable and oxidizable carbon sources, and for the contextual availability of genome wide information in the form of genetic maps, DNA microarray, and collections of barcoded mutants. The comparison of the whole genome analysis with the microarray experiments (99.9% coverage) and with the phenotypic analysis of 4688 barcoded haploid mutants (80.2% coverage), shed light on the genes involved in the response to CdS QDs, both in vivo and in vitro. The results have clarified the mechanisms involved in the exposure to CdS QDs, and whether these ENMs and Cd2+ exploited different pathways of response, in particular related to oxidative stress and to the maintenance of mitochondrial integrity and function. Saccharomyces cerevisiae remains a versatile and robust alternative for organismal toxicological studies, with a high level of heuristic insights into the toxicology of more complex eukaryotes, including mammals.

Environment, biodiversity and ecosystem services are essential to ensure food security and nutrition. Managing natural resources and mainstreaming biodiversity across agriculture sectors are keys towards a sustainable agriculture focused on resource efficiency. Vapour Pressure Deficit (VPD) is considered the main driving force of water movements in the plant vascular system, however the tools available to monitor this parameter are usually based on environmental monitoring. The driving motif of this paper is the development of an in-vivo sensor to monitor the effects of VPD changes in the plant. We have used an in vivo sensor, termed "bioristor", to continuously monitor the changes occurring in the sap ion's status when plants experience different VPD conditions and we observed a specific R (sensor response) trend in response to VPD. The possibility to directly monitor the physiological changes occurring in the plant in different VPD conditions, can be used to increase efficiency of the water management in controlled conditions thus achieving a more sustainable use of natural resources.

Nanomaterial-specific response of quantum dots and the underlying mechanisms of their interaction with plants are poorly understood. In this study, we investigated the mechanism of cadmium sulfide-quantum dot (CdS-QD) uptake and stress response in soybean (Glycine max) plants using sensitive bio-analytical techniques. We adopted shotgun-proteomics and targeted analysis of metabolites and gene expression in the tissues of soybean plants exposed to 200 mg L-1 CdS-QDs in vermiculite for 14 days. The molecular response in the soybeans as a function of surface coatings on CdS-QDs, specifically, trioctylphosphine oxide, polyvinylpyrrolidone, mercaptoacetic acid and glycine was also tested. The biological response of CdS-QDs was compared to Cd-ions and bulk-CdS to identify the nanomaterial-specific response. The transmembrane proteins involved in uptake and genes including NRAMP6 and HMA8 were regulated differently in CdS-QD-treated plants compared to Cd-ion-treated plants. The ATP-dependent ion-transporters in the membranes presented feedback mechanisms in the soybean roots to restrict the uptake of CdS-QDs and simultaneously altered the mineral acquisition. CdS-QDs perturbed major metabolic pathways in soybeans including glutathione metabolism, tricarboxylic acid cycle, glycolysis, fatty acid oxidation and biosynthesis of phenylpropanoid and amino acids. This study provides clear evidence that the toxic responses and tolerance mechanisms in plants are specific to CdS-QD exposure and not entirely due to leaching of Cd ions.