Aroma in foodstuff is considered an essential attribute since it is closely related to the consumer acceptance of foodstuffs. Electronic nose (e-nose) system is composed by an array of gas sensor and has emerged as a promising alternative for the aroma volatile compounds recognition. In this study, a lab-made e-nose system comprising of an array of different polyaniline-based sensors has been used for aroma discrimination (apple, strawberry, and grape) in gummy candy. The sensor array was comprised by interdigitated graphite electrodes, using tracing paper substrate and sensitive layer of polyaniline (Pani) obtained by in situ and interfacial synthesis deposited by the in situ adsorption polymerization of aniline and layer-by-layer (LbL) methods. The sensors were characterized in relation to humidity and the Pani-in situ/PSS LbL layer presenting the higher sensitivity, a quite interesting feature for its use as a gas sensor. It has been demonstrated that the lab-made e-nose has been highly efficient in the discrimination of different concentrations of aromas added to gummy candies with excellent sensitivity and a limit of detection in the range of parts-per-billion, so demonstrated the applicability in food matrices. 相似文献
Advanced persistent threats (APTs) have rocketed over the last years. Unfortunately, their technical characterization is incomplete—it is still unclear if they are advanced usages of regular malware or a different form of malware. This is key to develop an effective cyberdefense. To address this issue, in this paper we analyze the techniques and tactics at stake for both regular and APT-linked malware. To enable reproducibility, our approach leverages only publicly available datasets and analysis tools. Our study involves 11,651 regular malware and 4686 APT-linked ones. Results show that both sets are not only statistically different, but can be automatically classified with F1 > 0.8 in most cases. Indeed, 8 tactics reach F1 > 0.9. Beyond the differences in techniques and tactics, our analysis shows thats actors behind APTs exhibit higher technical competence than those from non-APT malwares.
Engineered polylactic acid (PLA) nanoparticles synthesized from oligo(lactic acid) macromonomers have been studied over the last decades for controlled drug delivery. These macromonomers are typically produced via ring-opening polymerization (ROP) of the cyclic dimer lactide, initiated by 2-hydroxyethyl methacrylate (HEMA). This reaction route, despite leading to well-defined macromonomers, relies on the production of lactide from lactic acid, which burdens the ROP overall cost for more than 30%. In this work, we report the synthesis of PLA-based macromonomers by direct polycondensation of lactic acid in the presence of HEMA as a valuable alternative to ROP. In particular, we compare the two processes side by side, focusing on the production of three HEMA-LAn macromonomers, with n = 2, 4, and 6. Detailed kinetic models are developed for both reaction systems, and the corresponding parameters are estimated by fitting the experimental data. Through these models, the reaction kinetics as well as the time evolution of the entire chain length distributions of the products from polycondensation and ROP could be reliably predicted. This way, we demonstrated that polycondensation is a valuable alternative to ROP only for macromonomers with an average chain length of up to 4 and that ROP remains the main route to longer chains, when a strict control over the chain length distribution is required. 相似文献
Photoelectrodes nanoscale interface design has become a key factor to enhancing their photoelectrochemical performance for water splitting by reducing the photogenerated charge recombination, thus ensuring their efficient separation, transport, and collection. In this work, hematite (α-Fe2O3) photoanodes were prepared from a simple and scalable methodology capable of synergistically mitigating the charge loss and recombination at all interfaces (i.e., fluorine-doped tin oxide/hematite, hematite/hematite, and hematite/electrolyte) and achieving overall efficiency of ∼50% for the water oxidation reaction compared to pristine photoelectrodes. The external quantum efficiency at 1.23 V versus reversible hydrogen electrode of pristine hematite was enhanced 6.7 times with the modifications of the three interfaces (Al2O3/NbH/NiFeOx). Electrochemical impedance spectroscopy and intensity-modulated photocurrent spectroscopies were applied to probe and monitor the photogenerated charge carrier dynamics revealing a substantial improvement in charge separation and collection at the back-contact interface as well as a partial mitigation of the surface states at the hematite–electrolyte interface. 相似文献
Visual Odometry (VO) is a fundamental technique to enhance the navigation capabilities of planetary exploration rovers. By processing the images acquired during the motion, VO methods provide estimates of the relative position and attitude between navigation steps with the detection and tracking of two-dimensional (2D) image keypoints. This method allows one to mitigate trajectory inconsistencies associated with slippage conditions resulting from dead-reckoning techniques. We present here an independent analysis of the high-resolution stereo images of the NASA Mars 2020 Perseverance rover to retrieve its accurate localization on sols 65, 66, 72, and 120. The stereo pairs are processed by using a 3D-to-3D stereo-VO approach that is based on consolidated techniques and accounts for the main nonlinear optical effects characterizing real cameras. The algorithm is first validated through the analysis of rectified stereo images acquired by the NASA Mars Exploration Rover Opportunity, and then applied to the determination of Perseverance's path. The results suggest that our reconstructed path is consistent with the telemetered trajectory, which was directly retrieved onboard the rover's system. The estimated pose is in full agreement with the archived rover's position and attitude after short navigation steps. Significant differences (~10–30 cm) between our reconstructed and telemetered trajectories are observed when Perseverance traveled distances larger than 1 m between the acquisition of stereo pairs. 相似文献