Multistage Transformation Research Articles

DSP design protection in CE through algorithmic transformation based structural obfuscation

Structural obfuscation offers a means to effectively secure through obfuscation the contents of an intellectual property (IP) cores used in an electronic system-on-chip (SoC). In this work a novel structural obfuscation methodology for protecting a digital signal processor (DSP) IP core at the architectural synthesis design stage. The proposed approach specifically targets protection of IP cores that involve complex loops. Five different algorithmic level transformation techniques are employed: loop unrolling, loop invariant code motion, tree height reduction/increment, logic transformation and redundant operation removal. Each of these can yield camouflaged functionally equivalent designs. In addition, low cost obfuscated design is generated through proposed approach through the use of multi-stage algorithmic transformation and particle swarm optimization (PSO)-drive design space exploration (DSE). Results of proposed approach yielded an enhancement obfuscation of 22 % and reduction in obfuscated design cost of 55 % compared to similar prior art.

Static and Dynamic Disorder in Metastable Phases of Tin Oxide

The multistage transformation of Sn3O4 to SnO2 in an oxygen-free atmosphere has been studied using hydrothermally synthesized samples, both pristine and heated, with in situ X-ray diffractometry, Raman spectroscopy, differential scanning calorimetry, dielectric spectroscopy, and ex situ X-ray photoelectron and nuclear magnetic resonance spectroscopies. Experimental evidence consistently shows that, beginning from 250 °C, Sn3O4 converts to Sn2O3 and, from 350 °C, to SnO2, accompanied by the formation of metallic tin. These two stages are associated with frequency-dependent dielectric losses, as revealed by impedance measurements, which also indicate a significant conductivity of 1.78 eV in activation energy. It is speculated that the relaxation-like processes relate to the transition from static to dynamic disorder and then to order in the oxygen sublattice.

Spatial Control of Functional Response in 4D-Printed Active Metallic Structures

We demonstrate a method to achieve local control of 3-dimensional thermal history in a metallic alloy, which resulted in designed spatial variations in its functional response. A nickel-titanium shape memory alloy part was created with multiple shape-recovery stages activated at different temperatures using the selective laser melting technique. The multi-stage transformation originates from differences in thermal history, and thus the precipitate structure, at various locations created from controlled variations in the hatch distance within the same part. This is a first example of precision location-dependent control of thermal history in alloys beyond the surface, and utilizes additive manufacturing techniques as a tool to create materials with novel functional response that is difficult to achieve through conventional methods.

Therapeutic implication of ‘Iturin A’ for targeting MD-2/TLR4 complex to overcome angiogenesis and invasion

Tumor angiogenesis and invasion are deregulated biological processes that drive multistage transformation of tumors from a benign to a life-threatening malignant state activating multiple signaling pathways including MD-2/TLR4/NF-κB. Development of potential inhibitors of this signaling is emerging area for discovery of novel cancer therapeutics. In the current investigation, we identified Iturin A (A lipopeptide molecule from Bacillus megaterium) as a potent inhibitor of angiogenesis and cancer invasion by various in vitro and in vivo methods. Iturin A was found to suppress VEGF, a powerful inducer of angiogenesis and key player in tumor invasion, as confirmed by ELISA, western blot and real time PCR. Iturin A inhibited endothelial tube arrangement, blood capillary formation, endothelial sprouting and vascular growth inside the matrigel. In addition, Iturin A inhibited MMP-2/9 expression in MDA-MB-231 and HUVEC cells. Cancer invasion, migration and colony forming ability were significantly hampered by Iturin A. Expressions of MD-2/TLR4 and its downstream MyD88, IKK-α and NF-κB were also reduced in treated MDA-MB-231 and HUVEC cells. Western blot and immunofluorescence study showed that nuclear accumulation of NF-κB was hampered by Iturin A. MD-2 siRNA or plasmid further confirmed the efficacy of Iturin A by suppressing MD-2/TLR4 signaling pathway. The in silico docking study showed that the Iturin A interacted well with the MD-2 in MD-2/TLR4 receptor complex. Conclusively, inhibition of MD-2/TLR4 complex with Iturin A offered strategic advancement in cancer therapy.

Multi-stage martensitic transformation in Ni-rich NiTi shape memory alloys

Precipitation hardening is an effective way to improve the functional stability of NiTi shape memory alloys. The precipitates, mainly Ni4Ti3, could be introduced by aging treatment in Ni-rich NiTi alloys. However, the presence of Ni4Ti3 precipitates could disturb the transformation behavior, resulting in the multi-stage martensitic transformation (MMT). With the presence of MMT, it is difficult to control the transformation behavior, and thus limits the applicability of NiTi alloys. In this work, previous efforts on explaining the observed MMT are summarized. The difficulties in developing a unified explanation are discussed, and a possible way to avoid the MMT is proposed.

Quantitative assessment of retained austenite in quenching and partitioning treated multiphase steel

For multiphase steel, an efficient and accurate quantitative analysis of constituent phases is critical in understanding the mechanical mechanism and optimising its properties. A method based on image digitisation and the concept of categorised linear interception has been proposed to study the amount of retained austenite (RA) residing in different phases in quenching and partitioning treated multiphase steel. It was found that RA at different locations transformed in different strain stages due to considerable influence from the surrounding phases, and the stability of each type of RA was estimated according to the above mentioned method. The proposed multistage transformation was proved to be more accurate than a single stage stability model.

Coverage induced structural transformations of tetracene on Ag(110).

Self-assembly of tetracene on an anisotropic surface of Ag(110) has been investigated using scanning tunneling microscopy and low-energy electron diffraction. We observe multistage structural transformations of the self-assembled tetracene on Ag(110) as a function of molecular coverages, which are accompanied by the changes in molecular orientations. They are analyzed by a balance between multiple molecule-molecule and anisotropic substrate-molecule interactions.

An algorithm for multistage projective transformation adjustment for image superimposition

We propose a multistage algorithm for constructing a projective transformation based on arbitrary sets of keypoint pairs, with the sets containing more than four keypoint pairs. In the course of calculation of a homography matrix, unsuccessful keypoint pairs are detected and rejected. Experimental results on image superimposition using projective transformations for homogeneous and heterogeneous images are presented. Methods for assessing the quality of image superimposition, which include the local and integral estimates of the superimposition quality, are proposed.

Real-time video fusion based on multistage hashing and hybrid transformation with depth adjustment

Concatenating multicamera videos with differing centers of projection into a single panoramic video is a critical technology of many important applications. We propose a real-time video fusion approach to create wide field-of-view video. To provide a fast and accurate video registration method, we propose multistage hashing to find matched feature-point pairs from coarse to fine. In the first stage of multistage hashing, a short compact binary code is learned from all feature points, and then we calculate the Hamming distance between each two points to find the candidate-matched points. In the second stage, a long binary code is obtained by remapping the candidate points for fine matching. To tackle the distortion and scene depth variation of multiview frames in videos, we build hybrid transformation with depth adjustment. The depth compensation between two adjacent frames extends into multiple frames in an iterative model for successive video frames. We conduct several experiments with different dynamic scenes and camera numbers to verify the performance of the proposed real-time video fusion approach.

ChemInform Abstract: Stimulating Excursions into Organolead Chemistry: Modular Domino Sequences Triggered by Oxidative Cleavage

AbstractReview: [123 refs.

Multistage martensitic transformation in high temperature aged Ti48Ni52 shape memory alloy

Aging effects on the transformation behavior of Ti48Ni52 SMA aged at 600 °C and 550 °C were investigated. The transformation evolution of specimens aged at 600 °C and at 550 °C can be classified into three and two periods, respectively. During aging at 600 °C, the specimens undergo B2↔M1 in period I, B2↔M1 + B2↔M2 in period II, and B2↔M2 in period III (M represents the B19′ martensite). During aging at 550 °C, the specimens undergo B2→R→M1/M1→B2 in periods I and II, and an additional B2↔M2 in period II. In period I, only Ti3Ni4 precipitates (ppts) form in the B2 matrix. In period II, Ti3Ni4 and Ti2Ni3 ppts coexist, and Ti3Ni4 depletion zones occur around Ti2Ni3 plates, inducing B2↔M2. In period III, only Ti2Ni3 plates exist. The occurrence of B2→R→M1 or B2→M1 in period I is related to whether the Ti3Ni4 ppts have a coherent interface or not. Schematic diagrams for periods I ∼ III are proposed to interpret the observed transformation behavior. The difference in Ni-content in the matrix near the Ti3Ni4 and Ti2Ni3 ppts affects the transformation temperatures of B2↔B19′.

Photoinduced insulator-to-metal transition and surface statistics of VO2 monitored by elastic light scattering.

Measurements of ultrafast light scattering within a hemisphere are performed for statistical analysis of nonequilibrium processes in VO2 epitaxial film. A Gerchberg-Saxton error reduction algorithm is applied for accurate calculation of a surface autocorrelation function from light scattering data and for partial reconstruction of a power spectral density function. Upon ultrafast photoinduced phase transition of VO2, the elastic light scattering reveals anisotropic grain-size-dependent dynamics. It was found that the transition rate depends on the optical absorption and orientation of VO2 grains with respect to polarization of the pump pulse. An observed stepwise evolution of surface autocorrelation length and transient anisotropy of the scattering field presumably originates from complex multistage transformation of VO2 lattice on a subpicosecond time scale.

Geochemical behaviors of HPHT gas reservoirs in the Yinggehai Basin and the efficient gas accumulation mode in its diapir flanks

The Yinggehai Basin is a Cenozoic high-temperature and high-pressure basin where diapir and thermal fluid activities were so strong that the deeply-sourced natural gas accumulated in the shallow traps in the diapir structures. A total of 11 exploratory wells were drilled in 8 diapir structures before 2010, but no commercial gas discoveries were made, provoking a hot debate on the possibility of discovering medium-to-large quality gas reservoirs in the middle and deep layers of the diaper structures. A comprehensive analysis of hydrocarbon generation kinetics, reservoir distribution and sealing conditions revealed the following findings. (1) Three gas-charging mechanisms were identified in the study area, namely slow free gas charging and accumulation under buoyancy, slow charging, evolving and accumulation of water soluble gas, and mixed-phase episodic accumulation. (2) In the high-temperature and high-pressure zones in the core of the diapir, the early gas reservoirs experienced multi-stage transformation at later periods, thus the possibility of forming large gas reservoirs dominated by hydrocarbon is small. In the flanks of the diapir, the early gas reservoirs may be well preserved at later stages, thus it is possible to discover primary gas pools. In the non-diapir zones, water soluble gas reservoirs may occur. (3) Three gas accumulation modes may exist in the study area, namely “the mixed-phase transformation mode” of semi-closed overpressure system in the core and periphery of a diapir, “the gas-phase seepage mode” in the flanks of a diapir, and “the water-phase desolvation mode” of a closed over-pressured system in the non-diapir zones. The analysis revealed that the failure of the previous exploratory drilling was caused mainly by emplacing the wells in the core of the diapir structures. The geochemical behaviors further support that the flanks of a diapir is the favorable place for high-temperature and high-pressure gas accumulation. Exploration practices based on these understandings finally led to the discovery of the large Dongfang 13-1/13-2 gas fields.

Effect of Aging Temperature and time on the Transformation Behavior of a Ti-50.8 at.% Ni Alloy with Small Grains

A Ti-50.8 at.% Ni alloy with small grains (average grain size of 1.8μm) was subjected to various aging treatments. It is found that the frequently reported multi-stage martensitic transformation, i.e. the transformation including two B19’ martensite or two rhombohedral R-phase transformations, is absent in this study. The samples aged at 523–573K show a single stage austenite↔R-phase transformation. A normal austenite→R-phase→martensite transformation is detected in the samples aged at 623–823K. The origin of this phenomenon and the effect of grain size on the aging microstructure is discussed.

Features of Multistage Thermoelastic B2–R–B19′ Martensitic Transformations in Heterophase Single Crystals of Ti–Ni Alloys

In heterophase Ti50.0–xNi50.0+x (х = 0.8–1.0 at.%) single crystals after aging at 823 K for 1.5 h at the heating/cooling rate (15 ± 1) K/min and stepwise aging at 823 K for 1.5 h plus aging at 573–623 K for 1 h, multi-stage martensitic transformations are observed: there are three peaks of heat release in the DSC (differential scanning calorimetry) curves. The first peak is associated with a B2–R-transformation and increased electrical resistance ρ and the other two correspond to the development of an R–B19′-martensitic transformation occurring in two stages, and are followed by a two-stage drop of electrical resistance in the ρ(T) plot. The high-temperature stage of the R–B19′-martensitic transition is associated with transformations under the action of local stress fields in the vicinity of disperse Ti3Ni4 particles measuring ~400 nm, while the low-temperature stage is associated with transformations in the spaces between large particles containing fine disperse β′-phase particles isostructural with respect to the matrix, measuring 3–5 nm, which are formed during slow cooling from 823 K or in the course of low-temperature aging at 573–623 K.

Microstructures and damping capacity of TiNiNbMo quaternary alloys with different Ti/Ni ratios

The effect of Ti/Ni ratio on the microstructure, phase transformation characteristics and damping capacity of TiNiNbMo quaternary alloys was investigated by scanning electron microscope, differential scanning calorimetry (DSC) and dynamic mechanical analyser. The microstructure observation showed that eutectic is weakened by the increase in the Ti/Ni ratio. The DSC test indicated that TiNiNbMo alloys with different Ti/Ni ratios exhibit multistage transformations including R transformation and B19′ martensite transformation, and the phase transformation temperature range was increased during cooling or heating. Meanwhile, when the Ti/Ni ratio is equal to 1·08, the alloy in martensite phase exhibited much higher damping than that of Ti50·1Ni49·9 binary alloy, which is mainly attributed to the precipitation of fine and dispersed β-Nb particles in the prime NiTi phases.

Effects of Ni concentration and aging conditions on multistage martensitic transformation in aged Ni-rich Ti–Ni alloys

The effects of Ni concentration and aging conditions on the multistage martensitic transformation (MMT) in aged Ni-rich Ti–Ni alloys have been investigated by differential scanning calorimetry and in situ scanning electron microscopy. The effect of Ni concentration was evaluated using Ti–50.6, 50.8 and 51.0at.% Ni alloys. These alloys were heat treated at 1223K for 3.6ks and then aged at 773K for 3.6ks. Although the triple-stage transformation appeared in the Ti–50.6 and 51at.% Ni alloys during cooling, the transformation sequence of the two alloys was completely different. Quadruple-stage transformation was observed in the Ti–50.8at.% Ni alloy. The characteristic microstructure responsible for the MMT in each of the aged alloys strongly depended on the degree of Ni supersaturation and the aging temperature and time. We have proposed and experimentally verified a general rule that explains the effects of Ni concentration and aging conditions on the microstructural changes and thus the MMT sequences. This will allow the MMT in Ni-rich Ti–Ni alloys to be controlled by selecting appropriate aging conditions.

Loss of Canonical Smad4 Signaling Promotes KRAS Driven Malignant Transformation of Human Pancreatic Duct Epithelial Cells and Metastasis

Pancreatic ductal adenocarcinoma (PDAC) is the fourth most common cause of cancer death in North America. Activating KRAS mutations and Smad4 loss occur in approximately 90% and 55% of PDAC, respectively. While their roles in the early stages of PDAC development have been confirmed in genetically modified mouse models, their roles in the multistep malignant transformation of human pancreatic duct cells have not been directly demonstrated. Here, we report that Smad4 represents a barrier in KRAS-mediated malignant transformation of the near normal immortalized human pancreatic duct epithelial (HPDE) cell line model. Marked Smad4 downregulation by shRNA in KRAS G12V expressing HPDE cells failed to cause tumorigenic transformation. However, KRAS-mediated malignant transformation occurred in a new HPDE-TGF-β resistant (TβR) cell line that completely lacks Smad4 protein expression and is resistant to the mito-inhibitory activity of TGF-β. This transformation resulted in tumor formation and development of metastatic phenotype when the cells were implanted orthotopically into the mouse pancreas. Smad4 restoration re-established TGF-β sensitivity, markedly increased tumor latency by promoting apoptosis, and decreased metastatic potential. These results directly establish the critical combination of the KRAS oncogene and complete Smad4 inactivation in the multi-stage malignant transformation and metastatic progression of normal human HPDE cells.

Quantitative microstructure analyses upon multistage martensitic transformation in an aged Ti–50.8at.% Ni alloy

Abstract Quantitative microstructure analyses upon multistage martensitic transformation (MMT) in an aged Ti–50.8 at.% Ni alloy have been performed by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). The alloy used was heat-treated at 1273 K for 3.6 ks and then aged at 773 K for 3.6 ks under regulated and unregulated atmospheres. The specimen heat-treated under the regulated atmosphere shows the single stage martensitic transformation in addition to the R-phase transformation. That is, B2 → R → M. On the other hand, the specimen heat-treated under the unregulated atmosphere shows the MMT with the sequence of B2 → R → M1 → M2 → M3. There are three exothermic peaks related to the martensitic transformation in addition to the R-phase transformation peak. The R-phase transformation takes place at the intermediate part of grains and around the grain boundaries. Subsequently, the first (M1) and second (M2) martensitic transformations occur at the intermediate part of grains and around the grain boundaries, respectively. Finally, the third transformation (M3) appears at the center part of grains directly from the B2 phase without via the R-phase transformation. The proposed transformation sequence is quantitatively proved by comparing the EBSD image with DSC curve.

Multistage transformation and charge effect during the fragmentation phase transition in atomic clusters

Compared with the macrosystem case, the phase transition occurring in fragmenting cluster systems depicts a much richer story. However, most experimental observations have been restricted to an extremely partial view of this picture due to the technical limitations of a large-range scan of the energy deposited in a selected cluster system. Here, taking charge-selected C${}_{60}$${}^{3+}$ and C${}_{60}$${}^{4+}$ as model systems, we experimentally explore the fragmentation phase transition (FPT) over a large energy range and directly observe some of the most important features of the FPT, the multistage transformation, and the charge effect.