Clams as pollution bioindicators in Kuwait''s marine environment: metal accumulation and depuration

This study has developed and verified clam transplantation for marine pollution monitoring in Kuwait and has assessed its reliability for monitoring pollution by heavy metals through laboratory and field transplantation experiments. In field experiments, live specimens of the clam Circenita callipyga were transplanted, either suspended in seawater or buried in sand, to 11 coastal sites in Kuwait; subsamples of transplanted clams were recovered at intervals over a 6-month period. In laboratory experiments, heavy metal accumulation for 36 days and depuration (body's release of pollutants) for 60 days in small and big clams were investigated. Clams subsampled in laboratory and field experiments were analyzed for Hg, Cu, V, Cd and Pb. Results showed the ability of clams to survive under the transplantation conditions. Accumulation of biofouling materials was a problem at only two transplantation sites and was overcome by periodic cleaning. Statistical analysis of laboratory experimental data showed significant accumulation of all test metals and significant depuration of Hg, Cu, V and Cd. Rates of metal accumulation and depuration differed in relation to clam size class. Field experiments indicated statistically significant increases in Hg and Cu concentrations in the transplanted clams at most stations, no change in Cd concentrations and an increase or, occasionally, a decrease in V and Pb concentrations.     

Occurrence and seasonal variations of Giardia in wastewater and river water from Al-Jinderiyah region in Latakia,Syria

ABSTRACT

This study investigates the occurrence and concentration of Giardia cysts in wastewater and river water samples in Al-Jinderiyah region, Latakia, Syria. A total of 120 samples were collected between October 2016 and October 2017 from influent and effluent of Al-Jinderiyah Waste Water Treatment Plant (WWTP) and from three contaminated river water sites. Samples were concentrated and subjected to microscopic examination. The results show that the concentrations of cysts ranged from 0 to 297 cysts/L in wastewater samples. The overall removal efficiency of cysts in the activated sludge WWTP was 84.35%. The concentrations of cysts ranged from 0 to 128.52 cysts/L in river water samples. The highest concentration in river water was recorded near the raw wastewater discharge point. Seasonal variations of Giardia cysts concentration were significant, and the highest concentrations were recorded in the rainy season. The results suggest that Giardia may pose a public health risk in the studied region.     

Separation of a compound effective against Biomphalaria alexandrina snails from the filtrate of Penicillium janthinellum

Biomphalaria alexandrina snails, as intermediate hosts of schistosomiasis, play a central role in dissemination of the disease. Control of these snails by chemical molluscicides adversely affects the aquatic environment, causing toxic and carcinogenic effects on non-target organisms. Searching for promising substances from biological origin becomes an urgent need to overcome these drawbacks. Screening tests were carried out on 236 fungal genera isolated from the habitat of freshwater snails in four Egyptian governorates. Twenty species were effective against B. alexandrina snails, but the most potent was Penicillium janthinellum as the value of LC₅₀ was 1.03%. Chemical analyses of this filtrate resulted in the separation of a compound effective against snails; it was identified as methyl gallate. Protein electrophoresis showed that both fungal filtrate and methyl gallate affect the protein pattern of snails’ haemolymph. Little or no mortality of Daphnia pulex individuals was observed after their exposure to sub lethal concentrations of each treatment.     

Pulsed co-electrodeposition and characterization of Ni-based nanocomposites reinforced with combustion-synthesized, undoped, tetragonal-ZrO(2) particulates

Nanostructured nickel matrix composites reinforced with nanosized, undoped, tetragonal zirconia has been synthesized by cathodic pulsed electrodeposition. The reinforcement is synthesized by the aqueous combustion synthesis route with glycine as the fuel and zirconyl nitrate as the oxidizer. The reinforcement and composite have been characterized by XRD, TEM and SEM coupled with EDS. The microhardness and thermal stability (Kissinger method) of the composite are evaluated. These values are compared with those of pure nickel deposited under the same conditions. The results show that the microhardness of the nickel matrix is enhanced by the presence of the reinforcement from 450 to 575 VHN. Also the strengthening due to grain size effects and dispersion strengthening effect are evaluated individually and the interparticle separation is estimated to be around 85?nm. The volume fraction of the reinforcement is estimated to be 12-15% and the particles are uniformly distributed and monodispersed in the nickel matrix. The thermal stability of the composite is better than that of pure nickel in contrast to some of the reported literature.     

Preparation and Evaluation of Some Cationic Starch Derivatives as Flocculants

Six types of cationic starch derivatives bearing different types of amino groups, i.e., primary, secondary and tertiary or quaternary ammonium salt, were prepared and evaluated as flocculants. Native and hydrolyzed maize starches were used as parent materials for these derivatives. The different factors affecting flocculation were studied. These factors include (a) flocculant dose, (b) pH of the flocculation medium, (c) chemical formula of the flocculant and (d) type of cationic starch, its molecular weight and nitrogen content.     

Effect of processing technique on the dispersion of carbon nanotubes within polypropylene carbon nanotube‐composites and its effect on their mechanical properties

Carbon nanotube‐reinforced polymer composites are being investigated as promising new materials having enhanced physical and mechanical properties. With regards to mechanical behavior, the enhancements reported thus far by researchers are lower than the theoretical predictions. One of the key requirements to attaining enhanced behavior is a uniform dispersion of the nanotubes within the polymer matrix. Although solvent mixing has been used extensively, there are concerns that any remaining solvent within the composite may degrade its mechanical properties. In this work, a comparison is carried out between solvent and “solvent‐free” dry mixing for dispersing multiwall carbon nanotubes in polypropylene before further melt mixing by extrusion. Various weight fractions of carbon nanotubes (CNTs) are added to the polymer and their effect on the mechanical properties of the resulting composites is investigated. Enhancements in yield strength, hardness, and Young's modulus when compared with the neat polymer, processed under similar conditions, are observed. Differences in mechanical properties and strain as a function of the processing technique (solvent or dry) are also clearly noted. In addition, different trends of enhancement of mechanical properties for the solvent and dry‐mixed extrudates are observed. Dry mixing produces composites with the highest yield strength, hardness, and modulus at 0.5 wt% CNT, whereas solvent mixing produces the highest mechanical properties at CNT contents of 1 wt%. It is believed that this difference is primarily dependent on the dispersion of CNTs within the polymer matrix which is influenced by the processing technique. Field emission scanning electron microscopy analysis shows the presence of clusters in large wt% CNT samples produced by dry mixing. Samples produced by solvent mixing are found to contain homogeneously distributed CNTs at all CNT wt fractions. CNT pull‐out is observed and may explain the limited enhancement in mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Systemic enhancement of papaverine transdermal gel for erectile dysfunction

To enhance the systemic transdermal delivery of papaverine for the treatment of erectile dysfunction, several factors that influence transdermal delivery of papaverine HCl were studied. The effects of membrane types for in vitro permeation study, human skin layers, solvent/cosolvent systems and the penetration enhancers on the transdermal permeation of papaverine HCl were investigated. A combination of caproic acid, ethanol and water in the volume ratio of 50%:30%:20% was chosen as penetration enhancer and incorporated in two gel bases: 18% Pluronic F-127 and 2% Carbopol 940. In vivo skin permeation studies were performed with two loading doses (0.6% and 2%) in rabbits. The flux and permeability coefficient of papaverine HCl through different human skin layers suggested that the major barrier layer for papaverine HCl was residing primarily in the stratum corneum. However, the viable epidermis and dermis layer also contributed certain degrees of diffusion resistance. Differential Scanning Calorimetry study showed that penetration enhancer exhibited a counter effect with papaverine HCl on the temperature and enthalpy in both gels. In vitro drug release study demonstrated significant increases in the steady-state flux, permeability coefficient and enhancement ratio in these gels. Faster drug transports and higher bioavailability were also observed in rabbits. Skin irritation test performed in rabbits demonstrated a mild skin reaction with mean PII scores of 2 and below; however the recovery was fast. In conclusion, caproic acid, ethanol and water in the volume ratio of 50%:30%:20% is an effective penetration enhancer to deliver papaverine HCl transdermally for systemic absorption.     

Study the effect of recycled pressurized air on oxygen transfer design parameters in sequencing batch reactor technology

Aeration process consumes more than 60% of the total energy required for wastewater treatment. The present study aims to save power consumption within wastewater treatment aeration process through recycling of the air flow. A new technique of aeration is used to increase oxygen transfer efficiency via exploiting recycled pressurized air. A pilot plant has been constructed to study the effect of using recycled pressurized air within sequencing batch reactor (SBR) model. The results showed that the new technique comparing with the conventional SBR model improved Standard oxygen transfer rate (SORT), Standard oxygen transfer efficiency (SOTE) and Standard aeration efficiency (SAE). In particular, the new technique enhanced (SAE) with 10 and 4% at gauge pressure values 0.5 atm. and 2 atm. respectively. On the other hand, intermittent aeration enhanced (SAE) with 15 and 5% at gauge pressure values 0.5 atm. and 2 atm. respectively.     

Na2BaMg（PO4）2： synthesis, crystal structure and europium photoluminescence properties

Na2BaMg(PO4)2 was synthesized and characterized by X-ray diffraction, differential thermal analysis (DTA), 31P NMR spectroscopy and photoluminescence measurements. This compound crystallized in the P3m...