Industrial by-products-derived binders for in-situ remediation of high Pb content pyrite ash: Synergistic use of ground granulated blast furnace slag and steel slag to achieve efficient Pb retention and CO2 mitigation.

Ordinary Portland cement (OPC) is a cost-effective and conventional binder that is widely adopted in brownfield site remediation and redevelopment. However, the substantial carbon dioxide emission during OPC production and the concerns about its undesirable retention capacity for potentially toxic elements strain this strategy. To tackle this objective, we herein tailored four alternative binders (calcium aluminate cement, OPC-activated ground-granulated blast-furnace slag (GGBFS), white-steel-slag activated GGBFS, and alkaline-activated GGBFS) for facilitating immobilization of high Pb content pyrite ash, with the perspectives of enhancing Pb retention and mitigating anthropogenic carbon dioxide emissions. The characterizations revealed that the incorporation of white steel slag efficiently benefits the activity of GGBFS, herein facilitating the hydration products (mainly ettringite and calcium silicate hydrates) precipitation and Pb immobilization. Further, we quantified the cradle-to-gate carbon footprint and cost analysis attributed to each binder-Pb contaminants system, finding that the application of these alternative binders could be pivotal in the envisaged carbon-neutral world if the growth of the OPC-free roadmap continues. The findings suggest that the synergistic use of recycled white steel slag and GGBFS can be proposed as a profitable and sustainable OPC-free candidate to facilitate the management of lead-contaminated brownfield sites. The overall results underscore the potential immobilization mechanisms of Pb in multiple OPC-free/substitution binder systems and highlight the urgent need to bridge the zero-emission insights to sustainable in-situ solidification/stabilization technologies.

Development of a Smart Wireless Multisensor Platform for an Optogenetic Brain Implant.

Implantable cell replacement therapies promise to completely restore the function of neural structures, possibly changing how we currently perceive the onset of neurodegenerative diseases. One of the major clinical hurdles for the routine implementation of stem cell therapies is poor cell retention and survival, demanding the need to better understand these mechanisms while providing precise and scalable approaches to monitor these cell-based therapies in both pre-clinical and clinical scenarios. This poses significant multidisciplinary challenges regarding planning, defining the methodology and requirements, prototyping and different stages of testing. Aiming toward an optogenetic neural stem cell implant controlled by a smart wireless electronic frontend, we show how an iterative development methodology coupled with a modular design philosophy can mitigate some of these challenges. In this study, we present a miniaturized, wireless-controlled, modular multisensor platform with fully interfaced electronics featuring three different modules: an impedance analyzer, a potentiostat and an optical stimulator. We show the application of the platform for electrical impedance spectroscopy-based cell monitoring, optical stimulation to induce dopamine release from optogenetically modified neurons and a potentiostat for cyclic voltammetry and amperometric detection of dopamine release. The multisensor platform is designed to be used as an opto-electric headstage for future in vivo animal experiments.

Mechanistic insights into Pb and sulfates retention in ordinary Portland cement and aluminous cement: Assessing the contributions from binders and solid waste.

Identifying immobilization mechanisms of potentially toxic elements (PTEs) is of paramount importance in the field application of solidification/stabilization. Traditionally, demanding and extensive experiments are required to better access the underlying retention mechanisms, which are usually challenging to quantify and clarify precisely. Herein, we present a geochemical model with parametric fitting techniques to reveal the solidification/stabilization of Pb-rich pyrite ash through conventional (ordinary Portland cement) and alternative (calcium aluminate cement) binders. We found that ettringite and calcium silicate hydrates exhibit strong affinities for Pb at alkaline conditions. When the hydration products are unable to stabilize all the soluble Pb in the system, part of the soluble Pb may be immobilized as Pb(OH)2. At acidic and neutral conditions, hematite from pyrite ash and newly-formed ferrihydrite are the main controlling factors of Pb, coupled with anglesite and cerussite precipitation. Thus, this work provides a much-needed complement to this widely-applied solid waste remediation technique for the development of more sustainable mixture formulations.

Fully Integrated Silicon Photonic Erbium-Doped Nanodiode for Few Photon Emission at Telecom Wavelengths.

Recent advancements in quantum key distribution (QKD) protocols opened the chance to exploit nonlaser sources for their implementation. A possible solution might consist in erbium-doped light emitting diodes (LEDs), which are able to produce photons in the third communication window, with a wavelength around 1550 nm. Here, we present silicon LEDs based on the electroluminescence of Er:O complexes in Si. Such sources are fabricated with a fully-compatible CMOS process on a 220 nm-thick silicon-on-insulator (SOI) wafer, the common standard in silicon photonics. The implantation depth is tuned to match the center of the silicon layer. The erbium and oxygen co-doping ratio is tuned to optimize the electroluminescence signal. We fabricate a batch of Er:O diodes with surface areas ranging from 1 µm × 1 µm to 50 µm × 50 µm emitting 1550 nm photons at room temperature. We demonstrate emission rates around 5 × 106 photons/s for a 1 µm × 1 µm device at room temperature using superconducting nanowire detectors cooled at 0.8 K. The demonstration of Er:O diodes integrated in the 220 nm SOI platform paves the way towards the creation of integrated silicon photon sources suitable for arbitrary-statistic-tolerant QKD protocols.

Variable optical true-time delay line breaking bandwidth-delay constraints.

Continuously variable true-time optical delay lines are typically subject to a constraint of the bandwidth-delay product, limiting their use in several applications. In this Letter, we propose an integrated topology that breaks the bandwidth-delay product limit. The device is based on multiple Mach-Zehnder Interferometers (MZIs) arranged in parallel, providing easier control and a larger bandwidth compared to ring resonator-based solutions. The functionality of this architecture is demonstrated with a 4-stage delay line by performing measurements in both the time and frequency domains. The delay line introduces a delay of 90 ps over a bandwidth of more than 22 GHz with a negligible group delay distortion, operates on a wavelength range of about 60 nm, and is scalable to a higher number of MZI stages.

Peptide-Based Sensor and Microfluidic Platform for IgG Antibody Detection by Differential Impedance Sensing.

Serological assays enable infection screening as relatively easy-to-operate approaches compared with standard methods. In addition, to be relevant for early diagnosis, specific antibody detection is important for epidemiological surveillance and quantitative detection has potential significance for evaluating the severity and prognosis of different diseases.Here, we describe the detection process based on differential impedance sensing of IgG antibodies labeled with polystyrene nanoparticles. The electrode differential configuration, the amplification with nanoparticle functionalization, the electronic reading, and the microfluidic protocol allow to reach a limit of detection below 100 pg/mL for commercial IgG antibody spiked in buffer.

The validation of converting pyrite ash-contaminated soil into End-of-Waste by the High-Performance Solidification/Stabilization process application.

One of the major challenges to establishing more sustainable management strategies than landfill disposal of metals-contaminated soils is the lack of End-of-Waste (EoW) criteria defined at the European and national levels. Another limitation stems from the scarcity of information on industrial-scale applications of treatment technologies able to obtain safe and reusable materials from such contaminated waste. In this context, the High-Performance Solidification/Stabilization process was applied for the full-scale remediation of pyrite ash-contaminated soil (ca. 24 000 m3 ), and a dedicated sampling and analytical protocol was developed and implemented to verify if the treated material obtained complied with the general EoW criteria established by article 6 of the Waste Framework Directive 2008/98/EC. The results of the leaching, ecotoxicological, and mechanical tests carried out on representative samples of the treated soil showed that this material (ca. 19 000 m3 ) could be classified as EoW and thus was deemed reusable both in-situ as filler for the excavation and ex-situ as road construction material. These results improve the knowledge of the performance of a state-of-the-art technique for the treatment of metals-contaminated soil. Furthermore, the developed monitoring plan can support future assessments on the compliance of materials obtained from contaminated soil with the general EoW criteria. Integr Environ Assess Manag 2023;19:961-969. © 2022 SETAC.

Optimal vaccination in a SIRS epidemic model.

We propose and solve an optimal vaccination problem within a deterministic compartmental model of SIRS type: the immunized population can become susceptible again, e.g. because of a not complete immunization power of the vaccine. A social planner thus aims at reducing the number of susceptible individuals via a vaccination campaign, while minimizing the social and economic costs related to the infectious disease. As a theoretical contribution, we provide a technical non-smooth verification theorem, guaranteeing that a semiconcave viscosity solution to the Hamilton-Jacobi-Bellman equation identifies with the minimal cost function, provided that the closed-loop equation admits a solution. Conditions under which the closed-loop equation is well-posed are then derived by borrowing results from the theory of Regular Lagrangian Flows. From the applied point of view, we provide a numerical implementation of the model in a case study with quadratic instantaneous costs. Amongst other conclusions, we observe that in the long-run the optimal vaccination policy is able to keep the percentage of infected to zero, at least when the natural reproduction number and the reinfection rate are small.

Temperature and wavelength drift tolerant WDM transmission and routing in on-chip silicon photonic interconnects.

We demonstrate a temperature and wavelength shift resilient silicon transmission and routing interconnect system suitable for multi-socket interconnects, utilizing a dual-strategy CLIPP feedback circuitry that safeguards the operating point of the constituent photonic building blocks along the entire on-chip transmission-multiplexing-routing chain. The control circuit leverages a novel control power-independent and calibration-free locking strategy that exploits the 2nd derivative of ring resonator modulators (RMs) transfer function to lock them close to the point of minimum transmission penalty. The system performance was evaluated on an integrated Silicon Photonics 2-socket demonstrator, enforcing control over a chain of RM-MUX-AWGR resonant structures and stressed against thermal and wavelength shift perturbations. The thermal and wavelength stress tests ranged from 27°C to 36°C and 1309.90 nm to 1310.85 nm and revealed average eye diagrams Q-factor values of 5.8 and 5.9 respectively, validating the system robustness to unstable environments and fabrication variations.

Impedance-Based Rapid Diagnostic Tool for Single Malaria Parasite Detection.

This paper presents a custom, low-cost electronic system specifically designed for rapid and quantitative detection of the malaria parasite in a blood sample. The system exploits the paramagnetic properties of malaria-infected red blood cells (iRBCs) for their magnetophoretic capture on the surface of a silicon chip. A lattice of nickel magnetic micro-concentrators embedded in a silicon substrate concentrates the iRBCs above coplanar gold microelectrodes separated by 3 µm for their detection through an impedance measurement. The sensor is designed for a differential operation to remove the large contribution given by the blood sample. The electronic readout automatically balances the sensor before each experiment and reaches a resolution of 15 ppm in the impedance measurement at 1 MHz allowing a limit of detection of 40 parasite/µl with a capture time of 10 minutes. For better reliability of the results, four sensors are acquired during the same experiment. We demonstrate that the realized platform can also detect a single infected cell in real experimental conditions, measuring human blood infected by Plasmodium falciparum malaria specie.

Separating arbitrary free-space beams with an integrated photonic processor.

Free-space optics naturally offers multiple-channel communications and sensing exploitable in many applications. The different optical beams will, however, generally be overlapping at the receiver, and, especially with atmospheric turbulence or other scattering or aberrations, the arriving beam shapes may not even be known in advance. We show that such beams can be still separated in the optical domain, and simultaneously detected with negligible cross-talk, even if they share the same wavelength and polarization, and even with unknown arriving beam shapes. The kernel of the adaptive multibeam receiver presented in this work is a programmable integrated photonic processor that is coupled to free-space beams through a two-dimensional array of optical antennas. We demonstrate separation of beam pairs arriving from different directions, with overlapping spatial modes in the same direction, and even with mixing between the beams deliberately added in the path. With the circuit's optical bandwidth of more than 40 nm, this approach offers an enabling technology for the evolution of FSO from single-beam to multibeam space-division multiplexed systems in a perturbed environment, which has been a game-changing transition in fiber-optic systems.

Amorphous-silicon visible-light detector integrated on silicon nitride waveguides.

Visible-light integrated photonics is emerging as a promising technology for the realization of optical devices for applications in sensing, quantum information and communications, imaging, and displays. Among the existing photonic platforms, high-index-contrast silicon nitride (Si3N4) waveguides offer broadband transparency in the visible spectral range and a high scale of integration. As the complexity of photonic integrated circuits (PICs) increases, on-chip detectors are required to monitor their working point for reconfiguration and stabilization operations. In this Letter, we present a semi-transparent in-line power monitor integrated on Si3N4 waveguides that operates in the red-light wavelength range (660 nm). The proposed device exploits the photoconductivity of a hydrogenated amorphous-silicon (a-Si:H) film that is evanescently coupled to an optical waveguide. Experimental results show a responsivity of 30 mA/W, a sensitivity of -45 dBm, and a sub-µs time response. These features enable the use of the proposed photoconductor for high-sensitivity monitoring and control of visible-light Si3N4 PICs.

High-sensitivity transparent photoconductors in voltage-controlled silicon waveguides.

On-chip optical power monitors are essential elements to calibrate, stabilize, and reconfigure photonic integrated circuits. Many applications require in-line waveguide detectors, where a trade-off has to be found between large sensitivity and high transparency to the guided light. In this work, we demonstrate a transparent photoconductor integrated on standard low-doped silicon-on-insulator waveguides that reaches a photoconductive gain of more than 106 and an in-line sensitivity as high as -60 dBm. This performance is achieved by compensating the effect of electric charges in the cladding oxide through a bias voltage applied to the chip substrate or locally through a gate electrode on top of the waveguide, allowing one to tune on demand the conductivity of the core to the optimum level.

An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles.

Calcium silicate hydrate (C-S-H) is the main binding phase in Portland cement. The addition of C-S-H nanoparticles as nucleation seeds has successfully been used to accelerate the hydration process and the precipitation of binding phases either in conventional Portland cement or in alternative binders. Indeed, the modulation of the hydration kinetics during the early-stage dissolution-precipitation reactions, by acting on the nucleation and growth of binding phases, improves the early strength development. The fine-tuning of concrete properties in terms of compressive strength and durability by designed structural modifications can be achieved through the detailed description of the reaction products at the atomic scale. The nano-sized, chemically complex and structurally disordered nature of these phases hamper their thorough structural characterization. To this aim, we implement a novel multi-scale approach by combining forefront small-angle X-ray scattering (SAXS) and synchrotron wide-angle X-ray total scattering (WAXTS) analyses for the characterization of Cu-doped C-S-H nanoparticles dispersed in a colloidal suspension, used as hardening accelerator. SAXS and WAXTS data were analyzed under a unified modeling approach by developing suitable atomistic models for C-S-H nanoparticles to be used to simulate the experimental X-ray scattering pattern through the Debye scattering equation. The optimization of atomistic models against the experimental pattern, together with complementary information on the structural local order from 29Si solid-state nuclear magnetic resonance and X-ray absorption spectroscopy, provided a comprehensive description of the structure, size and morphology of C-S-H nanoparticles from the atomic to the nanometer scale. C-S-H nanoparticles were modeled as an assembly of layers composed of 7-fold coordinated Ca atoms and decorated by silicate dimers and chains. The structural layers are a few tens of nanometers in length and width, with a crystal structure resembling that of a defective tobermorite, but lacking any ordering between stacking layers.

On-chip magnetophoretic capture in a model of malaria-infected red blood cells.

The search for new rapid diagnostic tests for malaria is a priority for developing an efficient strategy to fight this endemic disease, which affects more than 3 billion people worldwide. In this study, we characterize systematically an easy-to-operate lab-on-chip, designed for the magnetophoretic capture of malaria-infected red blood cells (RBCs). The method relies on the positive magnetic susceptibility of infected RBCs with respect to blood plasma. A matrix of nickel posts fabricated in a silicon chip placed face down is aimed at attracting infected cells, while healthy cells sediment on a glass slide under the action of gravity. Using a model of infected RBCs, that is, erythrocytes with methemoglobin, we obtained a capture efficiency of about 70% after 10 min in static conditions. By proper agitation, the capture efficiency reached 85% after just 5 min. Sample preparation requires only a 1:10 volume dilution of whole blood, previously treated with heparin, in a phosphate-buffered solution. Nonspecific attraction of untreated RBCs was not observed in the same time interval.

Differential Impedance Sensing platform for high selectivity antibody detection down to few counts: A case study on Dengue Virus.

We developed a biosensing system for serological detection of viruses based on the impedance variation between gold microelectrodes upon the capture of the target antibodies hybridized with nanobeads for signal amplification. The microfluidic platform core features a Differential Impedance Sensing (DIS) architecture between a reference and an active sensor able to reach nanoparticle resolution of few tens. The biosensor, functionalized with a copoly layer housing a synthetic peptide probe, has shown a limit of detection (LOD) below 100 pg/mL using a model IgG antibody spiked in a buffer. The biosensor was also tested with human serum samples for quantitative counts of anti-Dengue Virus antibodies, reaching a sensitivity that outperforms commercial ELISA kit. The system is perfectly suited to be easily reconfigured for novel probes by simply modifying the preparation of the biosensor chip surface, thus addressing a wide range of pathogens and diseases with clinically relevant concentrations for rapid immunoassays in a point of care setting.

Molecular Monitoring of SARS-CoV-2 in Different Sewage Plants in Venice and the Implications for Genetic Surveillance.

Wastewater-based epidemiology is now widely used as an indirect tool to monitor the spread of SARS-CoV-2. In this study, five different sample matrices representing diverse phases of the wastewater treatment process were collected during the second wave of SARS-CoV-2 from two wastewater treatment plants (WWTPs) serving the Civil Hospital and Sacca Fisola island in Venice, Italy. Positive SARS-CoV-2 detections occurred at both WWTPs, and data on viral genome detection rate and quantification suggest that the pellet (i.e., the particulate resulting from the influent) is a sensitive matrix that permits reliable assessment of infection prevalence while reducing time to results. On the contrary, analysis of post-treatment matrices provides evidence of the decontamination efficacy of both WWTPs. Finally, direct sequencing of wastewater samples enabled us to identify B.1.177 and B.1.160 as the prevalent SARS-CoV-2 lineages circulating in Venice at the time of sampling. This study confirmed the suitability of wastewater testing for studying SARS-CoV-2 circulation and established a simplified workflow for the prompt detection and characterization of the virus.

Polarization-transparent silicon photonic add-drop multiplexer with wideband hitless tuneability.

Flexible optical networks require reconfigurable devices with operation on a wavelength range of several tens of nanometers, hitless tuneability (i.e. transparency to other channels during reconfiguration), and polarization independence. All these requirements have not been achieved yet in a single photonic integrated device and this is the reason why the potential of integrated photonics is still largely unexploited in the nodes of optical communication networks. Here we report on a fully-reconfigurable add-drop silicon photonic filter, which can be tuned well beyond the extended C-band (almost 100 nm) in a complete hitless (>35 dB channel isolation) and polarization transparent (1.2 dB polarization dependent loss) way. This achievement is the result of blended strategies applied to the design, calibration, tuning and control of the device. Transmission quality assessment on dual polarization 100 Gbit/s (QPSK) and 200 Gbit/s (16-QAM) signals demonstrates the suitability for dynamic bandwidth allocation in core networks, backhaul networks, intra- and inter-datacenter interconnects.

A Lab-On-chip Tool for Rapid, Quantitative, and Stage-selective Diagnosis of Malaria.

Malaria remains the most important mosquito-borne infectious disease worldwide, with 229 million new cases and 409.000 deaths in 2019. The infection is caused by a protozoan parasite which attacks red blood cells by feeding on hemoglobin and transforming it into hemozoin. Despite the WHO recommendation of prompt malaria diagnosis, the quality of microscopy-based diagnosis is frequently inadequate while rapid diagnostic tests based on antigens are not quantitative and still affected by non-negligible false negative/positive results. PCR-based methods are highly performant but still not widely used in endemic areas. Here, a diagnostic tool (TMek), based on the paramagnetic properties of hemozoin nanocrystals in infected red blood cells (i-RBCs), is reported on. Exploiting the competition between gravity and magnetic forces, i-RBCs in a whole blood specimen are sorted and electrically detected in a microchip. The amplitude and time evolution of the electrical signal allow for the quantification of i-RBCs (in the range 10-105 i-RBC µL-1) and the distinction of the infection stage. A preliminary validation study on 75 patients with clinical suspect of malaria shows on-field operability, without false negative and a few false positive results. These findings indicate the potential of TMek as a quantitative, stage-selective, rapid test for malaria.

Taming the spread of an epidemic by lockdown policies.

We study the problem of a policymaker who aims at taming the spread of an epidemic while minimizing its associated social costs. The main feature of our model lies in the fact that the disease's transmission rate is a diffusive stochastic process whose trend can be adjusted via costly confinement policies. We provide a complete theoretical analysis, as well as numerical experiments illustrating the structure of the optimal lockdown policy. In all our experiments the latter is characterized by three distinct periods: the epidemic is first let to freely evolve, then vigorously tamed, and finally a less stringent containment should be adopted. Moreover, the optimal containment policy is such that the product "reproduction number × percentage of susceptible" is kept after a certain date strictly below the critical level of one, although the reproduction number is let to oscillate above one in the last more relaxed phase of lockdown. Finally, an increase in the fluctuations of the transmission rate is shown to give rise to an earlier beginning of the optimal lockdown policy, which is also diluted over a longer period of time.