Combined spectroscopic characterization of electron transfer at hybrid CuPcF(16)/GaAs semiconductor interfaces

We characterize photoinduced charge injection at the interface between a fluorinated copper phthalocyanine (CuPcF(16)) film deposited over a GaAs(100) wafer by means of pump-probe spectroscopy combined with ultraviolet photoemission spectroscopy (UPS) and electromodulated transmission spectroscopy. UPS characterization of the hybrid interface demonstrates that the CuPcF(16) 's lowest unoccupied molecular level (LUMO) is almost aligned with the GaAs conduction band. Upon photoexcitation of the hybrid interface with 150 fs pulses we observe an efficient photoinduced electron transfer from CuPcF(16) to GaAs. The evolution of interfacial CuPcF(16) charges appear to be strongly influenced by energy level alignment at the GaAs/CuPcF(16) heterojunction.     

Two‐Color Emitting Colloidal Nanocrystals as Single‐Particle Ratiometric Probes of Intracellular pH

Intracellular pH is a key parameter in many biological mechanisms and cell metabolism and is used to detect and monitor cancer formation and brain or heart diseases. pH‐sensing is typically performed by fluorescence microscopy using pH‐responsive dyes. Accuracy is limited by the need for quantifying the absolute emission intensity in living biological samples. An alternative with a higher sensitivity and precision uses probes with a ratiometric response arising from the different pH‐sensitivity of two emission channels of a single emitter. Current ratiometric probes are complex constructs suffering from instability and cross‐readout due to their broad emission spectra. Here, we overcome such limitations using a single‐particle ratiometric pH probe based on dot‐in‐bulk CdSe/CdS nanocrystals (NCs). These nanostructures feature two fully‐separated narrow emissions with different pH sensitivity arising from radiative recombination of core‐ and shell‐localized excitons. The core emission is nearly independent of the pH, whereas the shell luminescence increases in the 3–11 pH range, resulting in a cross‐readout‐free ratiometric response as strong as 600%. In vitro microscopy demonstrates that the ratiometric response in biologic media resembles the precalibralation curve obtained through far‐field titration experiments. The NCs show good biocompatibility, enabling us to monitor in real‐time the pH in living cells.     

Tattoo‐Paper Transfer as a Versatile Platform for All‐Printed Organic Edible Electronics

The use of natural or bioinspired materials to develop edible electronic devices is a potentially disruptive technology that can boost point‐of‐care testing. The technology exploits devices that can be safely ingested, along with pills or even food, and operated from within the gastrointestinal tract. Ingestible electronics can potentially target a significant number of biomedical applications, both as therapeutic and diagnostic tool, and this technology may also impact the food industry, by providing ingestible or food‐compatible electronic tags that can “smart” track goods and monitor their quality along the distribution chain. Temporary tattoo‐paper is hereby proposed as a simple and versatile platform for the integration of electronics onto food and pharmaceutical capsules. In particular, the fabrication of all‐printed organic field‐effect transistors on untreated commercial tattoo‐paper, and their subsequent transfer and operation on edible substrates with a complex nonplanar geometry is demonstrated.     

Ethical monitoring of brain-machine interfaces

The ethical monitoring of brain-machine interfaces (BMIs) is discussed in connection with the potential impact of BMIs on distinguishing traits of persons, changes of personal identity, and threats to personal autonomy. It is pointed out that philosophical analyses of personhood are conducive to isolating an initial thematic framework for this ethical monitoring problem, but a contextual refinement of this initial framework depends on applied ethics analyses of current BMI models and empirical case-studies. The personal autonomy-monitoring problem is approached by identifying various ways in which the inclusion of a robotic controller in the motor pathway of an output BMI may limit or jeopardize personal autonomy.     

A Sensitive and Effective Proteomic Approach to Identify She-Donkey’s and Goat’s Milk Adulterations by MALDI-TOF MS Fingerprinting

She-donkey’s milk (DM) and goat’s milk (GM) are commonly used in newborn and infant feeding because they are less allergenic than other milk types. It is, therefore, mandatory to avoid adulteration and contamination by other milk allergens, developing fast and efficient analytical methods to assess the authenticity of these precious nutrients. In this experimental work, a sensitive and robust matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling was designed to assess the genuineness of DM and GM milks. This workflow allows the identification of DM and GM adulteration at levels of 0.5%, thus, representing a sensitive tool for milk adulteration analysis, if compared with other laborious and time-consuming analytical procedures.     

A conservative nodal variational multiscale method for Lagrangian shock hydrodynamics

A new method based on a continuous, piece-wise linear approximation of the equations for Lagrangian shock hydrodynamics is presented. Numerical instabilities are controlled by a stabilizing operator derived using the paradigm of the variational multiscale analysis. Encouraging numerical comparisons with existing methods in the case of quadrilateral and hexahedral elements indicate that the proposed method is capable of preventing hourglass patterns in the solution, while maintaining accuracy in regions of smooth flow. The proposed approach satisfies Galilean invariance properties and hinges upon the interpretation of the Lagrangian shock hydrodynamics equations as a system of nonlinear wave equations. A specific implementation in terms of a predictor/multi-corrector version of the mid-point time integrator guarantees global conservation of mass, momentum, and total energy for each iterate. Stability and formal order of accuracy are investigated applying the von Neumann analysis to the linearized shock hydrodynamics equations in one dimension. This approach yields tight bounds for stable time-step estimation, formal second-order accuracy of the method in time and space, and valuable indications on the choice of the most appropriate values for the stabilization parameters present in the formulation.     

Stabilized Methods for Compressible Flows

This article reviews 25 years of research of the authors and their collaborators on stabilized methods for compressible flow computations. An historical perspective is adopted to document the main advances from the initial developments to modern approaches.     

Strained MOSFETs on ordered SiGe dots

The potential of strained DOTFET technology is demonstrated. This technology uses a SiGe island as a stressor for a Si capping layer, into which the transistor channel is integrated. The structure information of fabricated samples is extracted from atomic force microscopy (AFM) measurements. Strain on the upper surface of a 30?nm thick Si layer is in the range of 0.7%, as supported by finite element calculations. The Ge content in the SiGe island is 30% on average, showing an increase towards the top of the island. Based on the extracted structure information, three-dimensional strain profiles are calculated and device simulations are performed. Up to 15% enhancement of the NMOS saturation current is predicted.