Palestinian experience with sewage sludge utilizing reed beds

Management of sewage sludge is one of the main environmental problems in Palestine. More than 400 m³/day of aerobic sludge and 5000 m³/year of anaerobic sludge are disposed of randomly in the Gaza Strip, creating several environmental and health problems. Because of the political–economic situation, a low cost system for sludge treatment has to be adopted. The results of a pilot project using a reed bed system in the Gaza Strip are promising. Sludge that accumulated in a reed bed system over a 3-year period was found to be well mineralized and composted, and suitable for land application. The water that drained from the reed bed was found to contain very low concentrations of suspended solids (SS) and chemical oxygen demand (COD). This paper presents the results of a 3-year project using a reed bed for sewage sludge treatment in Gaza – Palestine. The quality of drained water and the quality and quantity of accumulated sludge were monitored in two drying beds, one planted with reeds and the other left as a conventional drying bed.     

Hyperphosphatemia among end‐stage renal disease patients in developing countries: A forgotten issue?

The prevalence of hyperphosphatemia and increased calcium-phosphorus product has never been evaluated in a large multicenter study in a developing country. Our aim is to study the prevalence of hyperphosphatemia in 38 HD centers in Egypt (as an example of a developing country) and to correlate it with different co-morbid conditions and the patient's demographic data. This is a cross-sectional study conducted on 1005 chronic kidney disease stage 5 patients (CKD-stage 5) on HD for a period of more than 1 year in 38 dialysis centers in Egypt. All patients were receiving calcium-based salts as a phosphate binder. Hyperphosphatemia and increased calcium-phosphorus product were evaluated and correlated with different parameters including age, sex, knowledge by diet parameters, HD session duration, the frequency of HD per week, the type of dialysis membrane, the surface area of the dialyzer, dialyzer phosphorus clearance (phosphorus KoA), and the type of dialysate. Other co-morbid medical conditions and evidence of IHD were also investigated. Hyperphosphatemia was present in 69.1% of cases and a high calcium-phosphorus product was present in 30.2%. A higher calcium-phosphorus product was found among males. 83.2% of those with a poor knowledge by diet parameters had hyperphosphatemia compared with 67.6% in patients with a satisfactory knowledge by diet parameters. 72.3% of patients using a membrane with low-to-medium clearance had hyperphosphatemia, compared with 67.2% using a membrane with a high clearance. Seventy-two percent of patients with IHD were hyperphosphatemic compared with 67.6% of the non-ischemic patients. Hyperphosphatemia is a major problem in dialysis patients in developing countries, reflecting differences from developed countries regarding dietary habits, ethnic factors, dialysis quality, types of dialysis membranes, as well as economic factors hampering the use of the more expensive phosphate binders. Extended dialysis hours may be a good alternative solution in developing countries.     

Control of postharvest decay in fruits and vegetables by irradiation

This paper deals with the effect of postharvest gamma-irradiation of strawberries and carrots on their organoleptic quality, storage capacity and chemical composition. Radiation doses of 25 krad for strawberries and 75 krad for carrots were chosen as optimum doses not causing significant changes in the organoleptic quality. We found that strawberries and carrots irradiated at a doseof 25 and 75 krad respectively, retained its microbiological stability even during storage at 12 degrees C (strawberries) and at 25-30 degrees C (carrots), respectively. It was also found that changes in chemical composition depend on storage temperature and time and are not affected substantially by irradiation.     

Developments in Alkaline Tin Electrorefining

Although alkaline stannate baths for electrorefining of tin have been used for some time, there is still room for improvement The effects of alkali concentration, current density and temperature on the cathodic current efficiency have been studied, and a bath temperature of 75°C is recommended. To avoid unstable conditions in the bath, a special treatment to the anode and application of an auxiliary cathode are necessary. Many of the metallic impurities present in the crude tin anode go into the slimes in the form of hydroxides, but lead impurities can only be tolerated if concentrations are less than one percent.     

The effect of additives on zinc deposited from zinc sulfate solutions

Zinc is industrially electrowon from acid zinc sulfate solutions at ambient temperatures. Some refining agents are usually added to improve the deposit qualities. Gelatin is a traditional additive, but other additives are also used. In the investigation described here, the basic parameters of deposition (e.g., current density, acid concentration, and zinc concentration) were optimized. Gelatin and a tetraalkylammonium salt (TAS) were used separately and in combination as grain refiners of the cathodic deposits. Current efficiency determination experiments were performed to investigate the role of these additives. Scanning electron micrographs of the cathodic deposits were obtained to examine the surface qualities of deposits at certain conditions. Results showed that gelatin is generally a better refiner, although TAS may be used in concentrations of 0.074 mg/l to 1 mg/l. A mixture of the two additives resulted in a decrease of current efficiency.     

Secure color image cryptosystem based on chaotic logistic in the FrFT domain

Multimedia Tools and Applications - Recently, the digital multimedia security technology has been an interesting research theme due to fast advancement in employing real time multimedia through...     

Study of deformation and form error due to press-fitting a thick cylinder into a square outer housing

The deformation and form error resulting from press-fitting a thick cylinder into a square housing with an inner circular hole were studied using finite element analysis. The results show the effect of diametral interference and housing thickness on the resulting deformation and form error. The dimensions of an assembly of two thick cylinders equivalent to the assembly studied was determined.     

Ultrasonic properties of ENR-EPDM rubber blends

Summary The velocities of propagation of longitudinal and transverse ultrasonic waves in epoxidized natural rubber-ethylene propylene diene monomer (ENR-EPDM) blends with EPDM content of 0,25,50,75 and 100 weight percent were measured at a frequency of 2 MHz using pulse echo method. Density of the rubber blend was also measured. Longitudinal modulus, shear modulus, Young's modulus, bulk modulus, Poisson's ratio, crosslink density, and microhardness, of the rubber blends were then calculated. The variations of these parameters with the content of EPDM have been discussed, based on the structural changes of the network. Received: 23 March 2002/Revised version: 31 January 2003/ Accepted: 31 January 2003 Correspondence to Hesham A. Afifi     

First Example of Benzothiazole Azo Dyes Containing Cyclopentadienyliron Polynorbornene Macromolecules

Soluble cationic organoiron polynorbornenes with pendent hetarylazo side chains have been synthesized via ring opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine)benzylideneruthenium(IV) dichloride (Grubbs' catalyst). The vibrantly colored organoiron polymers displayed weight average molecular weights between 24500 and 40900 and exhibited glass transition temperatures at 146 °C and 161 °C.     

Investigation of DC conductivity and switching phenomenon of Se80Te20−xGex amorphous system

Se₈₀Te_20−xGe_x (x = 5, 7 and 10 at%) chalcogenide glass system was prepared by the conventional melt-quenching technique. Thin films of different thicknesses (283–823 nm) were prepared by thermal evaporation technique. The DC conductivity and switching properties were investigated in the temperature range 303–373 K below the corresponding glass transition temperature. The obtained results of DC conductivity showed that it decreases with decreasing Te content in the considered system, while it increases with temperature as well as with film thickness through the studied range. The conduction activation energy has two values E_σ1 and E_σ2 indicating the presence of two different conduction mechanisms through the studied range of temperature. The obtained results of the temperature dependence of DC conductivity are explained in accordance with Mott and Davis model. The switching effect in amorphous films was also investigated. The switching phenomenon for these compositions was of the memory type. The mean value of the threshold voltage increases linearly with increasing film thickness in the range 283–823 mm, while it decreases exponentially with increasing temperature in the investigated range. Values of the threshold voltage and power activation energies were obtained for the investigated compositions. The obtained results agree with the electrothermal model for the switching process.