Security-enhanced cloud-based image secret sharing and authentication using POB number system

Recently, the image secret sharing technique based on POB (Permutation Ordered Binary) number systems has drawn attention in academia. Thanks to Singh et al.’s pioneer in combining image confidentiality and authentication to form a cloud-based image cryptosystem using the POB number system. However, for image confidentiality and integrity, there are always two main concerns of a new image cryptosystem: the protection from unauthorized disclosure and the sensitivity of tampering. To claim confidentiality and integrity guaranty of secure image cryptosystems is meaningful only when the cryptanalysis is taken into consideration. In this article, Singh et al.’s scheme has undergone the scrutiny and potential security weaknesses found. First, the secret image may leak under chosen-plain-image attacks. Second, the partial secret key deducible under cipher/share-image-only attacks is shown unneglectable. Precisely, it is potentially problematic since the security of image authentication only relies on the secrecy of the parameter r of POB number systems, but the parameter is also learned to know by a heuristic method. The main weak design has been shown by means of introducing theoretical analyses and conducting some counter experiments. As a result, in this study we have focused on proposing a security-enhanced POB-based image secret sharing scheme with five primary advantages: (1) high security to confidentiality, (2) lossless reconstructed secret image, (3) high security to integrity, (4) high detection accuracy, and (5) low time complexity. The experimental results and the further analysis demonstrate that the simple and secure improvement does work.

     

Fabrication of carbon nanotubes field emission cathode by composite plating

Carbon nanotubes (CNTs) have high aspect ratio and have great potential to be applied as the field emission cathode because of its large field enhancement factor. In this work, a high performance carbon nanotube field emission cathode (CNTFC) was fabricated by using a composite plating method. The CNTs were purified by acid solutions and then dispersed in electrobath with nickel ions at temperatures of 60, 70, or 80 degrees C for the electroless plating process on glass substrate. The resulting CNT-Ni composite film has strong adhesion on the glass substrate. The degree of graphitization and the microstructure of the CNTFCs were studied by Raman spectroscopy and scanning electron microscopy. The field emission properties of the CNTFCs show a low turn-on electric field E(on) of about 1.2 V/microm, and a low threshold electric field E(th) of about 1.9 V/microm. Such a composite plating method could be applied to the fabrication of large area CNT field-emission displays.     

S-Equol Protects Chondrocytes against Sodium Nitroprusside-Caused Matrix Loss and Apoptosis through Activating PI3K/Akt Pathway

Osteoarthritis (OA) is a common chronic disease with increasing prevalence in societies with more aging populations, therefore, it is causing more concern. S-Equol, a kind of isoflavones, was reported to be bioavailable and beneficial to humans in many aspects, such as improving menopausal symptoms, osteoporosis and prevention of cardiovascular disease. This study investigated the effects of S-Equol on OA progress in which rat primary chondrocytes were treated with sodium nitroprusside (SNP) to mimic OA progress with or without the co-addition of S-Equol for the evaluation of S-Equol’s efficacy on OA. Results showed treatment of 0.8 mM SNP caused cell death, and increased oxidative stress (NO and H₂O₂), apoptosis, and proteoglycan loss. Furthermore, the expressions of MMPs of MMP-2, MMP-3, MMP-9, and MMP-13 and p53 were increased. The addition of 30 μM S-Equol could lessen those caused by SNP. Moreover, S-Equol activates the PI₃K/Akt pathway, which is an upstream regulation of p53 and NO production and is associated with apoptosis and matrix degradation. As a pretreatment of phosphoinositide ₃-kinases (PI₃K) inhibitor, all S-Equol protective functions against SNP decrease or disappear. In conclusion, through PI₃K/Akt activation, S-Equol can protect chondrocytes against SNP-induced matrix degradation and apoptosis, which are commonly found in OA, suggesting S-Equol is a potential for OA prevention.     

Examining EFL instructors’ and students’ perceptions and acceptance toward M-learning in higher education

Universal Access in the Information Society - Due to the rapid development of mobile technologies, the perceptions and acceptance relating to mobile learning have been changing over the last few...     

Numerical analysis of coupled effects of pulsatile blood flow and thermal relaxation time during thermal therapy

The main purpose of this study is to investigate the coupled effects of the pulsatile blood flow in thermally significant blood vessels and the thermal relaxation time in living tissues on temperature distributions during thermal treatments. Considering the fact that propagation speed of heat transfer in solid tissues is actually finite according to experiments, the traditional Pennes bioheat transfer equation (PBTE) was modified to a wave bioheat transfer equation (WBTE) that contains both wave transportation and diffusion competing with each other and characterized by the thermal relaxation time. The wave behavior will be more dominant when the relaxation time is large. WBTE together with a coupled energy transport equation for blood vessel flow was used to describe the temperature evolution of our current tumor–blood vessel system, and the equations were numerically solved by the highly accurate multi-block Chebyshev pseudospectral method. Numerical results showed that temperature evolution from WBTE was quite different from their counterparts from PBTE due to the dominant wave feature under large relaxation time. For example, larger relaxation time would preserve high temperature longer and this effect is even more pronounced when heating is fast. It further implies that heat is drained more slowly when relaxation time is large, and would make thermal lesion region cover the tumor tissue, the heating target, better. This phenomenon would therefore hint that the traditional PBTE simulations might under-estimate the thermal dose exerted on tumor. As to the pulsation frequency of blood flow from heart beat which was originally predicted to be important here, it turned out that the thermal behavior is quite insensitive to pulsation frequency in the current study.     

The effect of tetrafluoromethane plasma post-treatment on the electrical property of tungsten oxide nanowires

The effects of tetrafluoromethane (CF4) plasma on the surface morphology, chemical compositions, and electrical property of tungsten oxide (W18O49) nanowires are investigated. The nanostructured tungsten oxide nanowires with average length of 250-350 nm were self-catalytically grown on Si substrate. By post-treatment with CF4 plasma for 10 min, the W18O49 nanowires on the substrate showed the highest current response. Longer CF4 plasma post-treatment time demonstrated higher etching effect which demolished the nanowires and resulted in lower conductivity of the samples. The disintegration of the W18O49 nanowires layer after CF4 plasma treatment, revealed physically by the decrease of the average thickness and chemically by the decrease of XRD peak ratio (I 23.0/I 26.0), was closely related to the overall electrical performance. The etching effect was further reveled by Raman spectra showing the evolution of O-W-O and W=O characteristics with the increased post-treatment time. Moreover, the improvement of the electrical property of W18O49 nanowires was elucidated by the exposure rate to explain the mechanism of plasma post treatment in three stages: passivation, degradation and ablation. The maximum exposure rate, corresponding to the maximum conductivity, was achieved by 10 min of CF4 plasma treatment. The time-differentiated exposure analyses confirmed the evolution of resistance of W18O49 nanowires on Si with different post-treatment time which supported the results of surface characterizations.     

Gas ionization sensors with carbon nanotube/nickel field emitters

Gas ionization sensors based on the field emission properties of the carbon nanotube/nickel (CNT/Ni) field emitters were first developed in this work. It is found that the breakdown electric field (E(b)) slightly decreases from 2.2 V/microm to 1.9 V/microm as the pressure of H2 gas increases from 0.5 Torr to 100 Torr. On the contrary, E(b) obviously increases from 2.9 V/microm to 6.5 V/microm as O2 gas pressure increases from 0.5 Torr to 100 Torr. This may be explained by the depression of the electron emission that caused by the adsorption of the O2 gas on the CNT emitters. The Raman spectra of the CNT/Ni emitters also show that more defects were generated on the CNTs after O2 gas sensing. The Joule heating effect under high current density as performing H2 sensing was also observed. These effects may contribute the pressure dependence on the breakdown electric field of the CNT/Ni gas ionization sensors.     

AR-12 Has a Bactericidal Activity and a Synergistic Effect with Gentamicin against Group A Streptococcus

Streptococcus pyogenes (group A Streptococcus (GAS) is an important human pathogen that can cause severe invasive infection, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The mortality rate of streptococcal toxic shock syndrome ranges from 20% to 50% in spite of antibiotics administration. AR-12, a pyrazole derivative, has been reported to inhibit the infection of viruses, intracellular bacteria, and fungi. In this report, we evaluated the bactericidal activities and mechanisms of AR-12 on GAS infection. Our in vitro results showed that AR-12 dose-dependently reduced the GAS growth, and 2.5 μg/mL of AR-12 significantly killed GAS within 2 h. AR-12 caused a remarkable reduction in nucleic acid and protein content of GAS. The expression of heat shock protein DnaK and streptococcal exotoxins was also inhibited by AR-12. Surveys of the GAS architecture by scanning electron microscopy revealed that AR-12-treated GAS displayed incomplete septa and micro-spherical structures protruding out of cell walls. Moreover, the combination of AR-12 and gentamicin had a synergistic antibacterial activity against GAS replication for both in vitro and in vivo infection. Taken together, these novel findings obtained in this study may provide a new therapeutic strategy for invasive GAS infection.     

Effective heating for tumors with thermally significant blood vessels during hyperthermia treatment

Significant cooling effect by blood vessels, particularly in treated tumor region, during hyperthermia treatment has been recognized by researchers. The present study investigated a heating strategy, using a preheating zone and adaptive optimization, to effectively reduce the cooling effect as thermally significant blood vessels flowed through treated region during hyperthermia treatment. The preheating zone is located in a vessel's entrance region adjacent to treated tumor and the heating strategy attempted to elevate blood temperature before blood flowing into the treated region. We numerically calculated blood and tissue temperatures using 3-D models and the goal of treatment was to reach a uniform therapeutic temperature in the tumor region using the proposed heating strategy. Results showed first, for large blood vessels, the heating strategy effectively elevated blood temperature at the entrance of treated tumor and reduced total tumor power deposition. Consequently, it helped to reach the ideal treated temperature on tumor more effectively, and avoided extreme power deposition due to the cooling effect of blood vessels entering the treated region. For small blood vessels, the preheating zone could further improve the treatment result. Secondly, heating flowing blood with adaptive optimization results in a unique phenomenon along blood flow paths. That is a strong convective nature of blood flow, which creates high thermal gradients in the treated region. Thus, it plays a different and significant role in adaptive optimization process as compared to thermal diffusion of solid tissues.     

Schisarisanlactones A and B: A new class of nortriterpenoids from the fruits of Schisandra arisanensis

Two novel highly oxygenated nortriterpenoids, schisarisanlactones A (1) and B (2), have been isolated from the fruits of Schisandra arisanensis, an endemic plant of Taiwan. Compounds 1 and 2 possess an unprecedented 5/5/7/5/5-fused pentacyclic ring system. The structures of both compounds were determined on the basis of spectroscopic analyses, especially 2D NMR and MS. A plausible biogenetic pathway of 1 was proposed. Schisarisanlactone A (1) showed significant anti-HIV activity.