Hash key-based image encryption using crossover operator and chaos

This paper proposes a color image encryption scheme using one-time keys based on crossover operator, chaos and the Secure Hash Algorithm(SHA-2). The (SHA-2) is employed to generate a 256-bit hash value from both the plain-image and the secret hash keys to make the key stream change in each encryption process. The SHA-2 value is employed to generate three initial values of the chaotic system. The permutation-diffusion process is based on the crossover operator and XOR operator, respectively. Experimental results and security analysis show that the scheme can achieve good encryption result through only one round encryption process, the key space is large enough to resist against common attacks,so the scheme is reliable to be applied in image encryption and secure communication.     

TT-BIP: using correct-by-design BIP approach for modelling real-time system with time-triggered paradigm

In order to combine advantages of real-time operating systems implementing the time-triggered (TT) execution model and model-based design frameworks, we aim at proposing a correct-by-design methodology that derives correct TT implementations from high-level models. This methodology consists of two main steps: (1) transforming the high-level model into an intermediate model which respects the TT communication principles and where all communications between components are simple send/receive interactions, and (2) transforming the obtained intermediate model into the programming language of the target platform. In this paper, we focus on the presentation of the transformational methodology of the first step of this design flow. This methodology produces a correct-by-construction TT model by starting from a high-level model of the application software in behaviour, interaction, priority (BIP). BIP is a component-based framework with formal semantics that rely on multiparty interactions for synchronizing components. Commonly in TT implementations, tasks interact with each other through a communication medium. Our methodology transforms, depending on a user-defined task mapping, high-level BIP models where communication between components is strongly synchronized, into TT model that integrates a communication medium. Thus, only inter-task communications and components participating in such interactions are concerned by the transformation process. We also provide correctness proofs of the transformation and apply it on an industrial case study.     

Reactivity of oxygen species formed upon N2O dissociation over Fe–ZSM-5 zeolite: CO oxidation as a model

The oxidative power toward CO of α-oxygen formed upon N₂O dissociation over isolated and binuclear Fe/ZSM-5 zeolite is investigated by means of DFT calculations. The two α-sites [Fe–O]⁺ and [Fe–(μO)–(μOH)–Fe]⁺ exchanged in ZSM-5 were considered since their activity in the N₂O decomposition was recently shown. Computed electronic properties, charge transfers and frequency analysis of α-oxygen and iron in [O–Fe–O]⁺ and [OFe–(μO)–(μOH)–FeO]⁺ suggest a Fe^II character for the isolated and Fe^IV for the binuclear Fe–ZSM-5 sites. Addition of CO on oxygen atoms reveals that along the oxidation reaction the valence state for the isolated iron is II and remains relatively constant while a clear change from IV to II is calculated for the binuclear iron. According to DFT calculations CO addition on the α-oxygen from the iron active sites induces a significant length increase of the Fe–α-oxygen bond. Whatever the α-sites, the addition of CO is strongly exothermic and leads to stable minima resembling an adsorbed CO₂ on iron active site. This reactivity is in line with the well known high reactivity of α-oxygen and the rapid CO₂ formation at low temperatures. Based on the calculated enthalpy values, the adsorption of CO is slightly more favourable on binuclear [OFe–(μO)–(μOH)–FeO]⁺ than over isolated [O–Fe–O]⁺ iron site. A comparison of the entropic parameters suggests the opposite with a stronger oxidative power of α-oxygen from isolated over those from binuclear iron site.     

Bioactive composites of hydroxyapatite/polyvinylpyrrolidone for bone regeneration applications

The implantation of bioactive composites for bone repair applications has recently gained the attention of many research groups. The present paper introduces a method for grafting of polyvinylpyrrolidone on the surface of hydroxyapatite (CaHAp) microcrystals by wet precipitation method to manufacture new composite scaffolds with suitability for bone tissue engineering. After grafting with the polymer, the degree of CaHAp crystallinity decreased, and its thermal behavior changed indicating a strong interaction between them. Homogenous clusters of CaHAp particles within the polymeric matrix were observed in combination with an increase in the roughness of the resulting structures. Bioactivity of the composites was tested using MTT assay; a higher viability of the seeded cells was observed relative to those cultured with CaHAp powder.     

Neuroendocrine tumours of the digestive tract report of two cases and literature review

Neuroendocrine tumors (NET) of the digestive system are rare. They comprise only 1% of all the tumors of the gastrointestinal tract. The aim of this study is to report two cases of exceptional localization of non secretary neuroendocrine tumors. Their difficulty in diagnosis, treatment and controversy in chemotherapy merit their study in depth. These are two patients that were treated in the department of general surgery (Beau Séjour) in Charles Nicolle Hospital for non secretary (NET) of the pancreas and stomach. The first was presented as a painless epigastria mass with frequent diarrhea. The second was presented as a painful mass in the left hypochondriac area without any other symptoms. Biochemical evaluation confirmed their non secretary properties. Surgery remains the first line of treatment. It was possible for the gastric, but not for the pancreatic tumor. Both were very advanced and had metastasis. Histopathological evaluation and immunohistochemical study using the method of peroxydase antiperoxydase (PAP) complexes for some special monoclonal antibodies confirmed the diagnosis. Chemotherapy of both cases was mal tolerated and was discussed in details.