Public key cryptosystems based on multivariate polynomials have been studied since the eighties. One of them, called c, was introduced in 1988 by Imai and Matsumoto, and broken in 1993 by Dobbertin in classified work ...
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Public key cryptosystems based on multivariate polynomials have been studied since the eighties. One of them, called c, was introduced in 1988 by Imai and Matsumoto, and broken in 1993 by Dobbertin in classified work he did for the German Federal Office for Information Security and later by Patarin (see Dobbertin et al. 2005, Patarin 1995). Since then, the construction of multivariate systems sharing a great deal of the c properties have become of particular interest. Dobbertin introduced in a series of classified papers and later in a challenge of the MysteryTwister-competition hosted by the Horst-Gortz-Institute in 2005, (see Dobbertin et al. 2005) together with the author, a system where the central mapping is a power mapping of degree 4 and shares almost all the properties of c. It was therefore called biquadraticc. The challenge remained unbroken and the security of these systems an open problem. As its key size is rather large, the interest in such systems became low during the last years. Due to the initiative of the European Telecommunications Standards Institute and the National Institute for Standards and Technology in creating standards for post-quantum cryptography, systems with bigger key sizes have become of interest for practical applications. In this paper we will consider biquadraticc and more general systems based on hidden monomials of degree k called k-ary c. We will prove a lower bound for the running time of attacks based on Grobner basis algorithms like F-4 or F-5. We will compute the first fall degree for k-ary c and give a counterexample to the first fall degree assumption. We will derive an estimate for the complexity of breaking the above mentioned cryptochallenge and give parameter sizes for secure systems by taking into account all known types of attacks. It will turn out that the security requirements yield systems with impractical key sizes even for applications in post-quantum cryptography. Although k-ary c is not of practical inter
Adopting orthogonal experiments, relevant machinability in wire cut electrical discharge machining (WEDM) of 2D c/Siccomposite was studied. The effects of electrical machining parameters (namely pulse width, pulse in...
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Adopting orthogonal experiments, relevant machinability in wire cut electrical discharge machining (WEDM) of 2D c/Siccomposite was studied. The effects of electrical machining parameters (namely pulse width, pulse interval, and the number of tubes) on machining speed and surface roughness were analyzed. In addition, the effect of fiber orientations on the machinability was also studied. The main effect and interaction of the selected electrical machining parameters were also discussed. The key results show that the fiber orientation effect on machining speed plays a weaker role in WEDM of this composite. For machining speed, the number of tubes and the pulse interval have no interaction in both of machining directions A and B. For surface roughness, the number of tubes and the pulse interval have obvious interaction in both of machining directions A and B. The fiber orientation has a larger effect on the surface roughness than that on machining speed in WEDM of this composite. After analyzing the material removal mechanism, some new significant results show that the carbon fibers are removed in the form of transverse and longitudinal fracture. Interfacial debonding between fiber carbon and Sic matrix, pit, and recast layer form on the machined surface. Micro cracks are observed in the carbon fiber, and a part of the micro cracks are cross.
The stability and cO tolerance of a self-made 20wt% Pt/Ti0.8Mo0.2O2-c mixed oxide-carbon composite supported electrocatalyst was compared to those of a commercial state-of-the-art PtRu/c electrocatalyst by means of cy...
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The stability and cO tolerance of a self-made 20wt% Pt/Ti0.8Mo0.2O2-c mixed oxide-carbon composite supported electrocatalyst was compared to those of a commercial state-of-the-art PtRu/c electrocatalyst by means of cyclic voltammetry and cOads stripping voltammetry measurements. On the Pt/Ti0.8Mo0.2O2-ccatalyst the oxidation of cO takes place at exceptionally low potential values (E-cO,E-onset=50mV);the onset potential is shifted to less positive potentials by 150mV compared to the PtRu/ccatalyst. A stability test involving 500 polarization cycles revealed that the PtRu/ccatalyst suffered more significant degradation than the composite supported Pt catalyst. XPS measurements indicated that the degradation is connected to ruthenium dissolution. At the same time, better electrocatalytic stability and increased cO tolerance of the Pt/Ti0.8Mo0.2O2-c electrocatalyst compared to the PtRu/ccatalyst was evidenced.
To help fill the knowledge gap regarding the potential human health impacts of food pigment TiO2, a comparative toxicity study was performed on a food-grade TiO2 (f-TiO2), a bulk TiO2 (b-TiO2), and a nano-sized TiO2 (...
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To help fill the knowledge gap regarding the potential human health impacts of food pigment TiO2, a comparative toxicity study was performed on a food-grade TiO2 (f-TiO2), a bulk TiO2 (b-TiO2), and a nano-sized TiO2 (Degussa P25), and in the nematode caenorhabditis elegans. Acute phototoxicity and chronic toxicity effects including reproduction, lifespan, and vulval integrity were evaluated. The f-TiO2, b-TiO2, and P25 had a primary particle size (size range) of 149 (53-308) nm, 129 (64-259) nm, and 26 (11-52) nm, respectively. P25 showed the greatest phototoxicity with a 24-h Lc50 of 6.0mg/L (95% cI 5.95, 6.3), followed by the f-TiO2 (Lc50=6.55mg/L (95% cI 6.35, 6.75)), and b-TiO2 was the least toxic. All three TiO2 (1-10mg/L) induced concentration-dependent effects on the worm's reproduction, with a reduction in brood size by 8.5 to 34%. They all caused a reduction of worm lifespan, accompanied by an increased frequency of age-associated vulval integrity defects (Avid). The impact on lifespan and Avid phenotype was more notable for P25 than the f-TiO2 or b-TiO2. Ingestion and accumulation of TiO2 particles in the worm intestine was observed for all three materials by light microscopy. These findings demonstrate that the food pigment TiO2 induces toxicity effects in the worm and further studies are needed to elucidate the human health implication of such toxicities.
cellular microRNAs(miRNAs) have been shown to modulate HcV infection via directly acting on the viral genome or indirectly through targeting the virus-associated host factors. Recently we generated a comprehensive map...
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cellular microRNAs(miRNAs) have been shown to modulate HcV infection via directly acting on the viral genome or indirectly through targeting the virus-associated host factors. Recently we generated a comprehensive map of HcV–miRNA interactions through genome-wide miRNA functional screens and transcriptomics analyses. Many previously unappreciated cellular miRNAs were identified to be involved in HcV infection, including miR-135a, a human cancerrelated miRNA. In the present study, we investigated the role of miR-135a in regulating HcV life cycle and showed that it preferentially enhances viral genome replication. Bioinformatics-based integrative analyses and subsequent functional assays revealed three antiviral host factors, including receptor interacting serine/threonine kinase 2(RIPK2), myeloid differentiation primary response 88(MYD88), and c-X-c motif chemokine ligand 12(cXcL12), as bona fide targets of miR-135a. These genes have been shown to inhibit HcV infection at the RNA replication stage. Our data demonstrated that repression of key host restriction factors mediated the proviral effect of miR-135a on HcV propagation. In addition,miR-135a hepatic abundance is upregulated by HcV infection in both cultured hepatocytes and human liver, likely mediating a more favorable environment for viral replication and possibly contributing to HcV-induced liver *** results provide novel insights into HcV–host interactions and unveil molecular pathways linking miRNA biology to HcV pathogenesis.
Aims The goal of this study was to examine, for the first time, the virulence and pathogenicity of aerosolized Burkholderia pseudomallei, strain NcTc 13392, in BALB/c mice in order to develop an animal model for testi...
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Aims The goal of this study was to examine, for the first time, the virulence and pathogenicity of aerosolized Burkholderia pseudomallei, strain NcTc 13392, in BALB/c mice in order to develop an animal model for testing novel medical countermeasures (McMs) for the treatment of human acute and subacute (a disease state between acute and chronic) melioidosis. Methods and Results BALB/c mice were exposed to varying doses of aerosolized bacteria. Acute disease was seen in animals exposed to a very-high dose (>= 10(3) cFU per animal) and death occurred 3-4 days postchallenge (pc). Bacteria were detected in the lungs, liver, kidney and spleen. In contrast, animals exposed to a low dose (<10 cFU per animal) survived to the end of the study (day 30 pc) but developed weight loss, a bacterial tissue burden and increasing clinical signs of infection from day 20 pc onwards, mimicking a subacute form of the disease. Pathological changes in the tissues mirrored these findings. conclusions This proof of concept study has shown that B. pseudomallei strain NcTc 13392 is virulent and pathogenic in BALB/c mice, when delivered by aerosol. By varying the doses of aerosolized bacteria it was possible to mimiccharacteristics of both human acute and subacute melioidosis, at the same time, within the same study. Significance and Impact of the Study Burkholderia pseudomallei, the aetiological agent of melioidosis, causes a serious and often fatal disease in humans and animals. Novel McMs are urgently needed for both public health and biodefense purposes. The present model provides a useful tool for the assessment and evaluation of new McMs (e.g. therapeutics and vaccines) and offers the potential for testing new treatments for both subacute to chronic and acute melioidosis prior to human clinical trials.
The aim of the present study was to evaluate the antifungal activity of seaweed champia parvula and identification of active compounds for this action. In this regard, c. parvula crude extracts were obtained from n-he...
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The aim of the present study was to evaluate the antifungal activity of seaweed champia parvula and identification of active compounds for this action. In this regard, c. parvula crude extracts were obtained from n-hexane, ethyl acetate, chloroform, methanol, and water used to study the antifungal action. Results showed that methanolic extract had potent action against c. albicans, c. tropicalis, T. mentagrophytes, and ***, with the highest inhibition of 16.7 mm found against c. tropicalis. Minimum inhibition concentration at 12.5 and minimum fungal concentration at 25 mu g/mL were found in the methanolic extract. Therefore, to identify the bioactive compound for this antifungal action in the methanolic extract, thin-layer chromatography (TLc) and reverse-phase high-performance liquid chromatography (RP-HPLc) were used. The RP-HPLc had three peaks with retention times at 3.30, 3.86, and 4.73 min, showing the presence of ester fatty acid compound. Further, these compounds were characterized by nuclear magnetic resonance (NMR), gas chromatography (Gc), and liquid chromatography-mass spectrometry (Lc-MS), which showed the presence of long-chain aliphatic fatty acid like eicosanoic acid with formation of oct-1-en-3-ol compounds attached.
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