Comparative anatomical investigation of five Artemisia L. (Anthemideae, Asteraceae) species in view of taxonomy

Comparative anatomical analysis of vegetative organs has been conducted on Artemisia campestris L., A. absinthium L., A. arborescens L., A. judaica L. and A. herba-alba Asso, using light microscopy, in order to examine the most important anatomical features and to find new valid taxonomic characters. Results have shown that general root, stem and leaf anatomical features and nonglandular and glandular trichomes are shared by all species. However, some characters (parenchyma sheath, which surrounded vascular bundle and extended to both epidermises, subepidermal collenchyma and the absence of secretory canals in the leaves) link together A. absinthium and A. arborescens from the same section. Some characters, as periderm and lignified pith parenchyma cells (A. campestris and A. arborescens), nonendodermal secretory canals in root cortex (A. absinthium and A. judaica) and secretory canals in the leaf phloem (A. judaica and A. herba-alba), connect species belonging to different sections. Moreover, some characters could be considered as species-specific, nonendodermal secretory canals in the root secondary phloem, triangular leaf shape on the cross section and secretory canals in the leaf parenchyma for A. campestris, secretory canals in the stem pith for A. absinthium, crystals in the pith parenchyma cells for A. arborescens and the absence of root secretory canals for A. herba-alba. Given results revealed qualitative characters, on the basis of which the studied species are anatomically distinguishable between each other, provide valuable features for better species identification and contribute to the anatomy of the genus Artemisia

Composition and antimicrobial activity of essential oils of artemisia judaica, a. Herba-alba and a. Arborescens from Libya

The essential oils obtained by hydrodistillation from the aerial parts of Artemisia judaica L., Artemisia herbaalba Asso. and Artemisia arborescens L. (cultivated) from Libya, were analyzed by GC and GC-MS. The antimicrobial properties were determined using the broth microdilution method against eight bacterial species: Bacillus cereus (clinical isolate), Micrococcus flavus (ATCC10240), Listeria monocytogenes (NCTC7973), Staphylococcus aureus (ATCC6538), Escherichia coli (ATCC35210), Pseudomonas aeruginosa (ATCC27853), Salmonella typhimurium (ATCC13311), Enterobacter cloacae (human isolates) and eight fungal species: Aspergillus niger (ATCC6275), A. ochraceus (ATCC12066), A. versicolor (ATCC11730), A. fumigatus (ATCC1022), Penicillium ochrochloron (ATCC9112), P. funiculosum (ATCC10509), Trichoderma viride (IAM5061) and Candida albicans (human isolate). The major constituents of A. arborescens oil were sesquiterpene hydrocarbons (47.4%). Oxygenated monoterpenes were the dominant constituents in the A. judaica and A. herba-alba oils (54.2% and 77.3%, respectively). Camphor (24.7%) and chamazulene (20.9%) were the major components in the essential oil of A. arborescens, chrysanthenone (20.8%), cis-chrysanthenyl acetate (17.6%) and cis-thujone (13.6%) dominated in the A. herba-alba oil, and the major constituents in the A. judaica oil were piperitone (30.21%) and cis-chrysanthenol (9.1%). The best antimicrobial activity was obtained for A. judaica oil and the lowest effect was noticed in A. arborescens oil. The effect of the tested oils was higher against Gram (+) than Gram (-) bacteria. All three oils showed the best antibacterial activity against Listeria monocytogenes and the lowest against Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, compared to streptomycin and ampicillin. All three oils showed better antifungal activities than ketoconazole, except A. arborescens oil against Aspergillus niger

The chemical composition, antimicrobial and antioxidant activities of the essential oil of Salvia fruticosa growing wild in Libya

The composition of essential oil isolated from Salvia fruticosa, wild growing in Libya, was analyzed by GC and GC-MS. Forty-five compounds could be identified. The essential oil contained 1,8-cineole (49.34%), camphor (7.53%), β-pinene (7.38%), myrcene (7.38%), α-pinene (5.15%), β-caryophyllene (4.13%) and α-terpineol (3.25). Antioxidant activity was analyzed using the DPP H free radical scavenging method and low antioxidant activity was found (IC50 = 15.53 mg/ml). The oil was also screened for its antimicrobial activity against eight bacteria (four Gram-negative and four Gram-positive) and eight fungi. The essential oil of S. fruticosa showed minimal inhibitory activity (MIC) at 0.125-1.5 mg/ml and bactericidal (MBC) at 0.5-2.0 mg/ml. In addition, it exhibited fungistatic (MIC) at 0.125-1.0 mg/ml and fungicidal effect (MFC) at 0.125-1.5 mg/ml.Projekat ministarstva br. 173029 i br. 17303

The chemical composition, antimicrobial and antioxidant activities of the essential oil of Salvia fruticosa growing wild in Libya

The composition of essential oil isolated from Salvia fruticosa, wild growing in Libya, was analyzed by GC and GC-MS. Forty-five compounds could be identified. The essential oil contained 1,8-cineole (49.34%), camphor (7.53%), β-pinene (7.38%), myrcene (7.38%), α-pinene (5.15%), β-caryophyllene (4.13%) and α-terpineol (3.25). Antioxidant activity was analyzed using the DPP H free radical scavenging method and low antioxidant activity was found (IC50 = 15.53 mg/ml). The oil was also screened for its antimicrobial activity against eight bacteria (four Gram-negative and four Gram-positive) and eight fungi. The essential oil of S. fruticosa showed minimal inhibitory activity (MIC) at 0.125-1.5 mg/ml and bactericidal (MBC) at 0.5-2.0 mg/ml. In addition, it exhibited fungistatic (MIC) at 0.125-1.0 mg/ml and fungicidal effect (MFC) at 0.125-1.5 mg/ml.Projekat ministarstva br. 173029 i br. 17303

Enhancing data privacy and access anonymity in cloud computing

There is a growing interest in cloud computing due to its various benefits such as the efficient utilization of computing resources. However, privacy and security concerns are among the main obstacles facing the widespread adoption of this new technology. For instance, it is more desirable for many potential organizations and users that privacy protections and access authorizations on their data stored in the cloud remain under their control and only authorized entities can have access to the data even for the cloud server. In this paper, we propose a method that enables cloud clients more control of data security requirements on their data stored in the cloud. The data is protected by a client before it is sent to the cloud in a secure manner that only authorized users can access it. To provide a complete protection from unauthorized access, even the cloud provider is prevented from revealing the data content and access control policies. The client or data owner has complete control on what methods to use to protect the data and on who can have access on the data. The proposed method is based on a combination of cryptography techniques, including the Chines Remainder Theorem, symmetric and asymmetric encryptions. The proposed method combines access control and key sharing in one mechanism. In addition, the proposed method allows a client to use a unique key to encrypt the data and attaches it securely to its encrypted data. Only authorized users can have access to the key in order to decrypt the encrypted data. The data has all the security requirements independently attached to it including the integrity proof. The proposed method is efficient and has its computational overheard minimized. With all the security requirements and metadata stored with the data itself, the proposed method is also flexible and suitable for protecting clients’ data in the cloud computing environment

Spectrum sensing strategy to enhance the QoS in White-Fi networks

The rapidly growing number of wireless devices running applications that require high bandwidths, has resulted in increasing demands for the unlicensed frequency spectrum. Given the scarcity of allocated unlicensed frequencies, meeting such demands can become a serious concern. Cognitive Radio (CR) technology opens the door for the opportunistic use of the licensed spectrum to partially address the issues relevant to the limited availability of unlicensed frequencies. Combining CR and Wi-Fi to form the socalled White-Fi networks, has been proposed for achieving higher spectrum utilization. This article discusses the spectrum sensing in White-Fi networks and the impacts that it has on the QoS of typical applications. It also reports the analysis of such impacts through various simulation studies. Our results demonstrate the advantages of an adaptive sensing strategy that is capable of changing the related parameters based on QoS requirements. We also propose such a sensing strategy that can adapt to the IEEE 802.11e requirements. The goal of the proposed strategy is the enhancement of the overall QoS of the applications while maintaining efficient sensing of the spectrum. Simulation results of the scenarios that implement the proposed mechanisms demonstrate noticeable QoS improvements compared to cases where common sensing methods are utilized in IEEE802.11 networks

Selecting the sensing method in cognitive radio and future networks : a QoS-aware fuzzy scheme

Scarcity of the radio frequency spectrum available for use by the vast number of wireless devices is already a challenge faced by ubiquitous communication networks, including the Internet of Things. The Cognitive Radio (CR) technology provides promising solutions to address part of such challenges. CR is based on allowing the so-called holes, the spectrums that remain unoccupied by their licensed users, to be utilized by others. To detect these holes, several spectrum sensing methods have been proposed by researchers. Each of these methods has its advantages and shortcomings for a given CR operation scenario. In particular, sensing methods can greatly affect the QoS levels of applications for various users of CR networks. In this paper, the effects of various spectrum sensing parameters and functions on the QoS levels of applications running on CR devices are reported. Based on those, the authors propose a QoS-aware fuzzy scheme for selecting the proper sensing method, from the catalog of available ones. We show that the proposed scheme mitigates the degrading impacts of the sensing operations on the QoS levels of a diverse range of CR-based applications

Spectrum sensing approach based on QoS requirements in White-Fi networks

Cognitive Radio (CR) technology opens the door for the opportunistic use of the licensed spectrum to partially address the issues relevant to the limited availability of unlicensed frequencies. Combining CR and Wi-Fi to form the so called White-Fi networks, has been proposed for achieving higher spectrum utilization. This paper discusses the spectrum sensing in White-Fi networks and the impacts that they have on the QoS of typical applications. It also reports the analysis of such impacts through various simulation studies. We also propose such a sensing strategy that can adapt to the IEEE 802.11e requirements. The proposed strategy aims to enhance overall QoS while maintaining efficient sensing. Simulation results of the proposed mechanism demonstrate a noticeable improvement in QoS

Spectrum sensing in cognitive radio networks : QoS considerations

The rapidly growing number of wireless communication devices has led to massive increases in radio traffic density, resulting in a noticeable shortage of available spectrum. To address this shortage, the Cognitive Radio (CR) technology offers promising solutions that aim to improve the spectrum utilization. The operation of CR relies on detecting the so-called spectrum holes, the frequency bands that remain unoccupied by their licensed operators. The unlicensed users are then allowed to communicate using these spectrum holes. As such, the performance of CR is highly dependent on the employed spectrum sensing methods. Several sensing methods are already available. However, no individual method can accommodate all potential CR operation scenarios. Hence, it is fair to ascertain that the performance of a CR device can be improved if it is capable of supporting several sensing methods. It should obviously also be able to select the most suitable method. In this paper, several spectrum sensing methods are compared and analyzed, aiming to identify their advantages and shortcomings in different CR operating conditions. Furthermore, it identifies the features that need to be considered while selecting a suitable sensing method from the catalog of available methods

Selection of spectrum sensing method to enhance Qos in cognitive radio networks

The massively increasing number of wireless communication devices has led to considerable growths in radio traffic density, resulting in a predictable shortage of the available spectrum. To address this potential shortage, the Cognitive Radio (CR) technology offers promising solutions that aim to improve the spectrum utilization. The operation of CR relies on detecting the so-called spectrum holes, i.e., the frequency bands when they are unoccupied by their licensed operators. The unlicensed users are then allowed to communicate using these spectrum holes. Consequently, the performance of CR is highly dependent on the employed spectrum sensing methods. Several sensing methods are already available or literarily proposed. However, no individual method can accommodate all possible CR operation scenarios. Hence, it is fair to ascertain that the performance of a CR device can be improved if it is capable of supporting several sensing methods. Then it should be able to effectively select the most suitable method. In this paper, several spectrum sensing methods are compared and analyzed, aiming to identify their advantages and shortcomings in different CR operating conditions. Furthermore, it identifies the factors that need to be considered while selecting a proper sensing method from the catalog of available methods