Dynamic group key agreement for resource-constrained devices using blockchains

Dynamic group key agreement (DGKA) protocols are one of the key security primitives to secure multiparty communications in decentralized and insecure environments while considering the instant changes in a communication group. However, with the ever-increasing number of connected devices, traditional DGKA protocols have performance challenges since each member in the group has to make several computationally intensive operations while verifying the keying materials to compute the resulting group key. To overcome this issue, we propose a new approach for DGKA protocols by utilizing Hyperledger Fabric framework as a blockchain platform. To this end, we migrate the communication and verification overhead of DGKA participants to the blockchain network in our developed scheme. This paradigm allows a flexible DGKA protocol that considers resource-constrained entities and trade-offs regarding distributed computation. According to our performance analysis, participants with low computing resources can efficiently utilize our protocol. Furthermore, we have demonstrated that our protocol has the same security features as other comparable protocols in the literature

Identification of Harmonic Current Contributions of Iron and Steel Plants Based on Time-Synchronized Field Measurements - Part I: at PCC

This is the first of a two-paper series, in which a field-data-based analytical method is proposed to determine the harmonic current contributions of each Iron and Steel (I&S) Plant supplied from the Point of Common Coupling (PCC) and the upstream loads at the utility side. The non-linear characteristics of the plants and the utility are modeled as harmonic current sources, whereas the linear parts of the proposed model consist of passive circuit elements. In the proposed method, the harmonic current contributions of loads are decoupled from the upstream effects and they are determined through the harmonic Norton's equivalent circuit model of the system constructed on the basis of the sample by sample, time-synchronized field measurements of load current and PCC voltage signals. This method can be applied to circuit schemes with any number of plants supplied from a given PCC. The results have shown that the proposed method can be used as a successful estimation tool to determine the harmonic current contributions of all I&S Plants connected to the PCC

Biochemically Investigation of the Effects of Nettle Seed Herbal Mixture on Alcohol Damaged Liver

It was experimentally investigated in this research how protective Nettle Seed Herbal Mixture is against ethanol which causes oxidative stress in rats and causes toxic effects in the liver with chronic use. 20 4-month-old female Wistar male rats were used in the study. All rats in the study were fed with normal pellet Mouse food during the experiment. 10 week application was done by dividing the rats into four equal groups. Application method is orally drinking method. First group is the control group. The second group is the alcohol group. This group was given 30% ethanol in order to cause chronic alcoholisms. The third group was the alcohol+ Nettle Seed Herbal Mixture group and the rats in this group were given liquid, which was 30% ethanol,+ Nettle Seed Herbal Mixture extract. Fourth group was Nettle Seed Herbal Mixture extract group and the rats in this group were given liquid, which was Nettle Seed Herbal Mixture extract. At the end of ten weeks, within the first 24 hours, blood species were obtained from the animals under anesthesia using appropriate techniques. Serum ALT and AST values of the obtained blood samples were studied by enzymatic methods in "Roche Cobas 6000" device.. Biochemically ALT and AST enzyme values and statistical analysis with SPSS programe were done. No significant difference was found between these four groups at the end of the analysis because p value was bigger than 0,005.</p

Comparison of initial efficacy and long-term follow-up of heparin-coated Jostent with conventional NIR stent.

The implantation of heparin-coated stents was reported to be well tolerated, but there are conflicting results about acute in-hospital complications. (sub)acute thrombosis rates, and long-term follow-up compared to uncoated stents. We compared the angiographic and clinical results after coronary placement of two stent models: the heparin-coated premounted Jostent and the uncoated premounted NIR stent. Of 710 patients revascularized, a total of 426 patients received Jostent (n = 230) or NIR stent (n = 196) implantation. The primary end points were acute or subacute thrombosis, urgent CABG, AMI or death, while the secondary end points were the comparison of the restenosis rates of the stents at the 6th month and of the functional angina classification of the stent groups at the 1st, 6th and 12th months. There were no significant differences between the Jostent and NIR stent groups regarding angiographic and procedural success. Acute thrombosis rates in the Jostent and NIR stent groups were similar while no subacute thrombosis was observed in either group. The major adverse cardiac event rates of the groups also did not differ. Angiographic restenosis occurred in 17% of the Jostent group and 16% of the NIR stent group (NS). The combined clinical and angiographic restenosis rate was also similar between the Jo and NIR groups (19% and 18%, respectively). Comparison of functional angina classes at the 1st, 6th and 12th months revealed no significant difference between the study groups. In conclusion, when compared with implantation of an uncoated premounted NIR stent, implantation of a heparin-coated premounted Jostent does not provide any more benefit with respect to initial efficacy, sub(acute) thrombosis and 6-month restenosis rates and 12-month clinical outcomes

CHEMICAL COMPOSITION, ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY OF THE ESSENTIAL OIL OF CRITHMUM MARITIMUM L.

In this study, the chemical constituents, antioxidant and antimicrobial activity of the essential oil of the plant species of Crithmum maritimum L. were evaluated. The essential oil was obtained by hydrodistillation method using a Clevenger-type apparatus. The constituents were analyzed by gas chromatography/mass spectroscopy (GC/MS). The major components of the essential oil were detected as γ terpinene (42.95 %), β- phellandrene (25.03 %). Total phenolic compounds were analyzed by Folin-Ciocalteu reagent method and found as 28.48 g gallic acid equivalent/g. Antioxidant capacity of essential oil was tested by using Trolox Equivalent Antioxidant Capacity (TEAC) assay in vitro, and total antioxidant capacity was found as 9.18 mg TE/g. The antibiotic assay of the essential oil on twelve pathogenic bacteria including Staphlococcus chromonogenes ATCC 43764, Staphlococcus xylosus ATCC 29971, Staphlococcus warneri ATCC 29971, Staphlococcus hominis ATCC 27844, Staphlococcus aureus PSC 18, Listeria monocytogenes ATCC 7644, Salmonella typhimurium ATCC 74028, Proteus vulgaris NRRL-B 123, Bacillus cereus ATCC 11778, Bacillus subtilis, Enterococcus fecalis ATCC 19433, Pseudomonas aurageniosa ATCC 27853 was examined with agar disc diffusion method and antimicrobial activity of the oil was evaluated to be high. </p

Square prism micropillars improve osteogenicity of poly(methyl methacrylate) surfaces

Osteogenicity and osteointegration of materials is one of the key elements of the success of bone implants. Poly(methyl methacrylate) (PMMA) is the basic compound of bone cement and has been widely investigated for other orthopedic applications, but its poor osteointegration and the subsequent loosening of implant material limits its widespread use as bone implants. Micropillar features on substrate surfaces were recently reported to modulate cell behavior through alteration of cell morphology and promotion of osteogenesis. Utilization of this pillar-decorated topography may be an effective approach to enhance osteogenicity of polymeric surfaces. The aim of this study was to investigate the effect of cell morphology on the micropillar features on attachment, proliferation, and osteogenic activity of human osteoblast-like cells. A series of solvent cast PMMA films decorated with 8 mu m high square prism micropillars with pillar width and interpillar distances of 4, 8 and 16 mu m were prepared from photolithographic templates, and primary human osteoblast-like cells (hOB) isolated from bone fragments were cultured on them. Micropillars increased cell attachment and early proliferation rate compared to unpatterned surfaces, and triggered distinct morphological changes in cell body and nucleus. Surfaces with pillar dimensions and gap width of 4 mu m presented the best osteogenic activity. Expression of osteogenic marker genes was upregulated by micropillars, and cells formed bone nodule-like aggregates rich in bone matrix proteins and calcium phosphate. These results indicated that micropillar features enhance osteogenic activity on PMMA films, possibly by triggering morphological changes that promote the osteogenic phenotype of the cells

Determining Total Phenolics, Anthocyanin Content and Ascorbic Acid Content in Some Plum Genotypes Grown in Ardahan Ecological Conditions

In this study, total phenol content, total anthocyanin content, brix, pH, titrable acidity and total ascorbic acid content in the five plum genotypes cultivated in Ardahan City are determined and sustenance of the plums are revealed. Total phenol content was determined with folin-ciocalteu’s method, total anthocyanin content was determined with pH differential method and total ascorbic acid was determined with 2,6-dichlorophenolindophenol method.It is detected that the genotype with the highest brix content (%13.9) and lowest acidity (%0.98) is cancur, the genotype with the lowest brix content (%11) and highest acidity (%2.06) is wild plum, the genotype with the highest content of total anthocyanin, total phenolic substance and ascorbic acid is the wild plum and the genotype with the least content of these is the water plum. As a result of the study, it is revealed that the plum fruit has high levels of phenolic substance, anthocyanin and ascorbic acid content, so it has a high sustenance.</p

Determining Total Phenolics, Anthocyanin Content and Ascorbic Acid Content in Some Plum Genotypes Grown in Ardahan Ecological Conditions

In this study, total phenol content, total anthocyanin content, brix, pH, titrable acidity and total ascorbic acid content in the five plum genotypes cultivated in Ardahan City are determined and sustenance of the plums are revealed. Total phenol content was determined with folin-ciocalteu’s method, total anthocyanin content was determined with pH differential method and total ascorbic acid was determined with 2,6-dichlorophenolindophenol method.It is detected that the genotype with the highest brix content (%13.9) and lowest acidity (%0.98) is cancur, the genotype with the lowest brix content (%11) and highest acidity (%2.06) is wild plum, the genotype with the highest content of total anthocyanin, total phenolic substance and ascorbic acid is the wild plum and the genotype with the least content of these is the water plum. As a result of the study, it is revealed that the plum fruit has high levels of phenolic substance, anthocyanin and ascorbic acid content, so it has a high sustenance

Platinum nanoparticles supported on nitrogen and sulfur-doped reduced graphene oxide nanomaterial as highly active electrocatalysts for methanol oxidation

A fuel cell is an electrochemical cell that converts a source fuel into an electrical current. It generates electricity inside a cell through reactions between a fuel and an oxidant, triggered in the presence of an electrolyte. Fuel cells have been attracting more and more attention in recent decades due to high-energy demands, fossil fuel depletions and environmental pollution throughout world. In this study, a facile and cost-effective catalysts have been developed on platinum nanoparticles (PtNPs) supported on nitrogen and sulfur-doped reduced graphene oxide (NSrGO). The successful synthesis of nanomaterials and the prepared glassy carbon electrode (GCE) surfaces were confirmed by transmission electron microscope (TEM), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS). According to TEM images, the average particle sizes of PtNPs were found to be approximately 15–20 nm. The effective surface areas (ESA) of NSrGO/GCE and PtNPs/NSrGO/GCE were calculated to be 148 and 469 cm2/mg, respectively. The PtNPs/NSrGO/GCE also exhibited a higher peak current for methanol oxidation than those of comparable GCE and NSrGO/GCE, providing evidence for its higher electro-catalytic activity. © 2016, Springer Science+Business Media New York