Synthesis of heterocyclic metal complexes and their evaluation as marine antifoulants

4-Amino-3-thio-1,24-triazolidine (L₁) and 4-amino-5-thio-1,3,4-thiadiazole (L_II) as well as their metal complexes of the general formulae ML_I·2H₂O and ML_IICl (M; Pb(II), Cd(II) and Zn(II)) were prepared. With Sn(II), we obtained Sn(L_I)₂·2H₂O and SnL_IICl, respectively. The structures of the compounds were identified through elemental analysis, and IR and UV spectra measurements, in addition to thermal analysis in case of the metal complexes. The antifouling properties of the compounds were tested by their incorporation into paint formulations which were applied to PVC substrates and tested in water from Alexandria western harbour. When the compounds were added at 17·5% by volume, the coated panels were fouled after 3 months of immersion. The addition of 6·7% by volume of tributyltin oxide to 15·8% of the prepared compounds in one formulation elevated the paint efficiency and prevented fouling for 11 months. Paint containing solely tributyltin oxide at the same concentration was inactive against algae.     

Influence of third monomer on the crystal phase transition behavior of ethylene-tetrafluoroethylene copolymer

Crystal phase transition between the low- and high-temperature phases has been investigated for ethylene (E)-tetrafluoroethylene (TFE) alternating copolymer (ETFE) containing the third monomeric species by the temperature dependent measurements of wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) and differential scanning calorimetry. Nonafluoro-1-hexene (NFH) and hexafluoropropylene (HFP) were chosen as the third monomers, where they are different in the side-branch length, -(CF₂)₃CF₃ and -CF₃, respectively. In the case of E/TFE/NFH copolymer (ET-C4F9), the crystal phase transition temperature of the original ETFE two-components copolymer was not very much affected by the existence of NFH in the range of NFH content from 0.7 to 3 mol%. Contrarily, the crystal phase transition temperature of E/TFE/HFP copolymer (ET-CF3) was found to decrease drastically with increasing HFP content. The melting temperature and the higher-order structure were also affected sensitively depending on the HFP content. This difference in phase transition behavior between ET-C4F9 and ET-CF3 copolymers is reasonably interpreted as follows: the short side groups (-CF₃) of HFP monomeric unit are included in the crystal lattice of E/TFE chains and the unit cell is expanded gradually with an increment of the HFP content, resulting in the decrease in phase transition point because of easier thermal motion of the chains. On the other hand, the long side groups [-(CF₂)₃CF₃] of NFH monomeric units are excluded out of the crystal lattice and located on the lamellar surfaces or in the amorphous region and do not affect very much the phase transition temperature even when the NFH content is increased. In association with such a change in crystal structure, the long period of stacked lamellar structure was found to decrease remarkably in the case of NFH, whereas it does not change very much for HFP, consistent with the interpretation of the above-mentioned WAXD data.     

A novel chromatographic separation technique using tertiary pyridine resin for the partitioning of trivalent actinides and lanthanides

A novel chromatographic separation technique using a tertiary pyridine type resin has been applied to the partitioning of the trivalent actinides (An) and lanthanides (Ln) and several successful results have been shown. In an alcoholic hydrochloric acid system, the trivalent An were clearly separated from the Ln, while no such group separation was achieved in an alcoholic nitric acid system. On the other hand, the nitric acid system was more effective for the intragroup (i.e. individual) separation of the trivalent An and the Ln than the hydrochloric acid system. On the basis of these results, a novel concept for the partitioning of the trivalent An and Ln using the present separation technique and its flowchart have been proposed with its advantages and disadvantages.     

Task scheduling mechanisms in cloud computing: A systematic review

Today, cloud computing has developed as one of the important emergent technologies in communication and Internet. It offers on demand, pay per use access to infrastructure, platforms, and applications. Due to the increase in its popularity, the huge number of requests need to be handled in an efficient manner. Task scheduling as one of the challenges in the cloud computing supports the requests for assigning a particular resource so as to perform effectively. In the resource management, task scheduling is performed where there is the dependency between tasks. Many approaches and case studies have been developed for the scheduling of these tasks. Up to now, a systematic literature review (SLR) has not been presented to discover and evaluate the task scheduling approaches in the cloud computing environment. To overcome, this paper presents an SLR‐based analysis on the task scheduling approaches that classify into (a) single cloud environments that evaluate cost‐aware, energy‐aware, multi‐objective, and QoS‐aware approaches in task scheduling; (b) multicloud environment that evaluates cost‐aware, multi‐objective, and QoS‐aware task scheduling; and (c) mobile cloud environment that is energy‐aware and QoS‐aware task scheduling. The analytical discussions are provided to show the advantages and limitations of the existing approaches.     

Ultra-wideband optical amplification with 3 dB bandwidth of 65 nmusing a gain-equalised two-stage erbium-doped fibre amplifier and Ramanamplification

A 3 dB gain-reduction bandwidth up to 65 nm (1549-1614 nm) is achieved using a two-stage erbium-doped fibre amplifier, together with an intermediate equaliser and Raman amplification in the transmission fibre     

Synchronized chaotic mode hopping in DBR lasers with delayedopto-electric feedback

We propose and demonstrate a scheme for generating synchronized chaotic mode hopping in two wavelength-tunable lasers. Chaotic mode hopping resulting in large hops in wavelength is induced by delayed feedback of an electrical signal proportional to the intensity of the laser output which passes through an optical filter. Mode hopping among up to 11 modes was experimentally observed and optical signals in each wavelength band show a different on-off modulation time series. Analysis of the time series indicates high dimensionality. By using a unidirectional coupling method that injects part of the output of one laser into another, we can synchronize the chaotic mode hopping of two separate lasers and obtain synchronized chaotic on-off modulation patterns in multiple corresponding wavelength bands. The robustness of the synchronization with respect to the parameter mismatch and the effects of the coupling strength are investigated. The chaotic mode hopping dynamics and synchronization are well described with a numerical model that includes the characteristics of the laser tuning and the filter transmission. A multiplexed data transmission scheme using chaotic carriers is proposed and experiments demonstrate that multiple messages can be simultaneously recovered when chaos synchronization is achieved     

Role of dietary lipids and butylated hydroxy anisol (BHA) administration on albino rats. Part I. Serum unsaturated fatty acids

Adult male albino rats were supplemented with edible plant oils, corn maize and cotton seed oils and their semihydrogenated forms (Heliopolis and Sultan cooking fats) for a period of 3 months. In general, the supplementation of tested oils produced increasing effect on the serum levels of total C18: 1, C18:2 and C20:4 unsaturated fatty acids (UFA). The increases were significant in case of feeding corn maize oil and Sultan cooking fat for total and C18: 1 and C18:2 UFA. However, the degree of significance was intensified by the feeding of cotton seed oil and Heliopolis cooking fat. Supplementation of Sultan cooking fat showed a significant increase in serum level of C20:4, while the other tested oils and Heliopolis cooking fat produced very highly significant increase. Butylated hydroxy anisol (BHA) produced no effect on the level of UFA when administered with dietary tested edible lipid but its role revealed by maintaining the higher level of UFA due to administration of oils and its semihydrogenated analogous.     

Electrical properties of Cu4ZnSnS2/ZnS heterojunction prepared by ultrasonic spray pyrolysis

Cu₂ZnSnS₄ (CZTS)/ZnS heterojunctions have been prepared by a successive deposition of ZnS and CZTS thin films by ultrasonic spray pyrolysis technique on glass substrates. The cupric chloride concentration has been varied in the starting solution in order to investigate its influence on device properties. CZTS/ZnS heterojunctions were characterized by recording their current-voltage characteristics at different temperatures. The obtained results exhibit a good rectifying behavior of the realized heterojunction. Analysis of these results yields saturation current, series resistance and ideality factor determination. From the activation energy of saturation current we inferred that the thermal emission through the barrier height is the dominant mechanism of the reverse current rather than the defects contribution.     

Cadmium sulfide thin films growth by chemical bath deposition

Cadmium sulfide (CdS) thin films have been prepared by a simple technique such as chemical bath deposition (CBD).A set of samples CdS were deposited on glass substrates by varying the bath temperature from 55 to 75 ℃ at fixed deposition time (25 min) in order to investigate the effect of deposition temperature on CdS films physical properties.The determination of growth activation energy suggests that at low temperature CdS film growth is governed by the release of Cd2+ ions in the solution.The structural characterization indicated that the CdS films structure is cubic or hexagonal with preferential orientation along the direction (111) or (002),respectively.The optical characterization indicated that the films have a fairly high transparency,which varies between 55％ and 80％ in the visible range of the optical spectrum,the refractive index varies from 1.85 to 2.5 and the optical gap value of which can reach 2.2 eV.It can be suggested that these properties make these films perfectly suitable for their use as window film in thin films based solar cells.     

The sprayed ZnO films: nanostructures and physical parameters

We synthesized the pure and indium-doped (IZO) ZnO films with a facile composition control spray pyrolysis route. The substrate temperature (T_s) and In-doping effects on the properties of as-grown films are investigated. The X-ray pattern confirms that the as-synthesized ZnO phase is grown along a (002) preferential plane. It is revealed that the crystalline structure is improved with a substrate temperature of 350 ℃. Moreover, the morphology of as-grown films, analyzed by AFM, shows nanostructures that have grown along the c-axis. The (3 × 3μm²) area scanned AFM surface studies give the smooth film surface RMS < 40 nm. The UV-VIS-IR measurements reveal that the sprayed films are highly transparent in the visible and IR bands. The photoluminescence analysis shows that the strong blue and yellow luminescences of 2.11 and 2.81 eV are emitted from ZnO and IZO films with a slight shift in photon energy caused by In-doping. The band gap is a bit widened by In-doping, 3.21 eV (ZnO) and 3.31 eV (IZO) and the resistivity is reduced from 385 to 8 Ω ·m. An interesting result is the resistivity linear dependence on the substrate temperature of pure ZnO films.