Photonic Side-Channel Analysis of Arbiter PUFs

As intended by its name, physically unclonable functions (PUFs) are considered as an ultimate solution to deal with insecure storage, hardware counterfeiting, and many other security problems. However, many different successful attacks have already revealed vulnerabilities of certain digital intrinsic PUFs. This paper demonstrates that legacy arbiter PUF and its popular extended versions (i.e., feed-forward and XOR-enhanced) can be completely and linearly characterized by means of photonic emission analysis. Our experimental setup is capable of measuring every PUF internal delay with a resolution of 6 ps. Due to this resolution, we indeed require only the theoretical minimum number of linear independent equations (i.e., physical measurements) to directly solve the underlying inhomogeneous linear system. Moreover, it is not required to know the actual PUF responses for our physical delay extraction. We present our practical results for an arbiter PUF implementation on a complex programmable logic device manufactured with a 180 nm process. Finally, we give an insight into photonic emission analysis of arbiter PUF on smaller chip architectures by performing experiments on a field programmable gate array manufactured with a 60 nm process.     

A 3D Cell-Free Bone Model Shows Collagen Mineralization is Driven and Controlled by the Matrix

Osteons, the main organizational components of human compact bone, are cylindrical structures composed of layers of mineralized collagen fibrils, called lamellae. These lamellae have different orientations, different degrees of organization, and different degrees of mineralization where the intrafibrillar and extrafibrillar minerals are intergrown into one continuous network of oriented crystals. While cellular activity is clearly the source of the organic matrix, recent in vitro studies call into question whether the cells are also involved in matrix mineralization and suggest that this process could be simply driven by the interactions of the mineral with extracellular matrix. Through the remineralization of demineralized bone matrix, the complete multiscale reconstruction of the 3D structure and composition of the osteon without cellular involvement are demonstrated. Then, this cell-free in vitro system is explored as a realistic, functional model for the in situ investigation of matrix-controlled mineralization processes. Combined Raman and electron microscopy indicate that glycosaminoglycans (GAGs) play a more prominent role than generally assumed in the matrix–mineral interactions. The experiments also show that the organization of the collagen is in part a result of its interaction with the developing mineral.     

Pure CuBi2O4 Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi2O3/CuO Grown by Pulsed Laser Deposition

A new method for enhancing the charge separation and photo‐electrochemical stability of CuBi₂O₄ photoelectrodes by sequentially depositing Bi₂O₃ and CuO layers on fluorine‐doped tin oxide substrates with pulsed laser deposition (PLD), followed by rapid thermal processing (RTP), resulting in phase‐pure, highly crystalline films after 10 min at 650 °C, is reported. Conventional furnace annealing of similar films for 72 h at 500 °C do not result in phase‐pure CuBi₂O₄. The combined PLD and RTP approach allow excellent control of the Bi:Cu stoichiometry and results in photoelectrodes with superior electronic properties compared to photoelectrodes fabricated through spray pyrolysis. The low photocurrents of the CuBi₂O₄ photocathodes fabricated through PLD/RTP in this study are primarily attributed to their low specific surface area, lack of CuO impurities, and limited, slow charge transport in the undoped films. Bare (without protection layers) CuBi₂O₄ photoelectrodes made with PLD/RTP shows a photocurrent decrease of only 26% after 5 h, which represents the highest stability reported to date for this material. The PLD/RTP fabrication approach offers new possibilities of fabricating complex metal oxides photoelectrodes with a high degree of crystallinity and good electronic properties at higher temperatures than the thermal stability of glass‐based transparent conductive substrates would allow.     

Theoretical design for 120 GHz semiconductor junction circulators: effects of different numbers of terms in the Green's function

A theoretical analysis of the predicted performance and field distributions for semiconductor junction circulators is based on Bosma's Green's function approach which involves a summation of infinite series in the mathematical derivation. The effects are considered of taking a different number of terms in the series, looking at three different circulators centred at 120 GHz. The narrowband semiconductor circulators show a similar effect to the ferrite junction circulator because the field distributions inside the semiconductor discs can be approximated by only considering the dominant modes. However, there is no dominant mode in the broadband circulator and the higher order modes play an important role in the operation of this circulator. In order to obtain a precise representation of the circulation effects inside both narrowband and broadband circulators, at least up to the 6th term, or 18 terms in all, are required to be added in the summation of Green's functions.     

An Organoid for Woven Bone

Bone formation (osteogenesis) is a complex process in which cellular differentiation and the generation of a mineralized organic matrix are synchronized to produce a hybrid hierarchical architecture. To study the mechanisms of osteogenesis in health and disease, there is a great need for functional model systems that capture in parallel, both cellular and matrix formation processes. Stem cell-based organoids are promising as functional, self-organizing 3D in vitro models for studying the physiology and pathology of various tissues. However, for human bone, no such functional model system is yet available. This study reports the in vitro differentiation of human bone marrow stromal cells into a functional 3D self-organizing co-culture of osteoblasts and osteocytes, creating an organoid for early stage bone (woven bone) formation. It demonstrates the formation of an organoid where osteocytes are embedded within the collagen matrix that is produced by the osteoblasts and mineralized under biological control. Alike in in vivo osteocytes, the embedded osteocytes show network formation and communication via expression of sclerostin. The current system forms the most complete 3D living in vitro model system to investigate osteogenesis, both in physiological and pathological situations, as well as under the influence of external triggers (mechanical stimulation, drug administration).     

Investigation of the photovoltage in por-Si/p-Si structures by the pulsed-photovoltage method

Photovoltaic phenomena in the structures por-Si/p-Si were investigated by the pulsed photovoltage method in the time interval 100 ns-10 ms using irradiation with nanosecond laser pulses with photon energies 1.4, 2.0, 2.8, and 3.7 eV. The data obtained show that besides the barrier photovoltage, due to the separation of nonequilibrium charge carriers in the space-charge region of p-Si at the por-Si/p-Si interface, there also exists an efficient mechanism of photovoltage formation due to charging of the surface of the por-Si nanostructure. This mechanism is explained as “optical doping” of a semiconductor and develops in a manner peculiar to semiconductor nanostructures. Fiz. Tekh. Poluprovodn. 32, 613–619 (May 1998)     

Unraveling the Reasons for Efficiency Loss in Perovskite Solar Cells

The effect of the presence of unreacted PbI₂ on the perovskite solar cells efficiency is reported. N,N‐Dimethylformamide vapor treatment is introduced to study the influence of complete conversion to a power conversion efficiency of the device. It is discovered that the optimized morphology of the PbI₂ under layer is essential to form a dense perovskite layer preventing recombination by direct contact between TiO₂ and a hole transporting layer, and to increase the charge collection efficiency. The present findings provide an insight into the morphology and growth mechanism of perovskite layer, the correlation between the device performance, and the film deposition process.     

Application de la voltampérométrie convolutionnele à la détermination du coefficient de diffusion des ions TiF 6 3− dans l'eutectique LiF−NaF−KF de 600°C a 900°C

Résumé Les coefficients de diffusion des ions TiF ₆ ^3– dans l'eutectique LiF–NaF–KF ont été déterminés de 600 à 900° C à l'aide de la semi-intégration des voltampérogrammes de réduction sur électrode de fer et d'oxydation sur électrode d'argent. Les interférences de la réduction de l'eutectique et d'un ménisque à la surface du bain ont été éliminées. Le coefficient de diffusion des ions TiF ₆ ^3– obéit à la loi d'Arrhénius selon:D=1.4×10^–2 exp (–6154/T) cm² s^–1.     

Neurophysiological Model of the Normal and Abnormal Human Pupil

A model of the pathways controlling the size of the human pupil is presented. Computer simulation of this model demonstrates the role played by each of the elements in the pupil pathways. Simulations of the effects of drugs and a few common abnormalities in the system also help to illustrate the workings of the internal processes. Computer models of this type can be used as teaching aids or as tools for testing of hypotheses regarding the system.