In the present work, the prepared Mn
0.8
Zn
0.2
Fe
2
O
4
ferrites (MZF) via recycling process of Zn–C batteries and auto-combustion route (using different fuels) were used to synthesize ...MZF/polypyrroly (PPy) nanocomposites via the in-situ polymerization technique. The core–shell structure formed was confirmed using X-ray diffraction, transmission electron microscopy and Fourier transform infrared techniques. The thermogravimetric measurements suggests that the presence of MZF was found to catalyze PPy thermal decomposition and decreasing its thermal stability through increasing its exposed surface. The core–shell structure was found also to vanish the MZF magnetic properties through the insulation effect of the non-magnetic PPy coat. A possible schematic diagram for the core–shell formation mechanism was suggested and discussed. AC-conductivity vs. temperature clearly reveals a metallic behavior of all the samples with a dramatic increase in the MZF conductivities by addition of PPy. The main conduction mechanism was found to be through polarons. The higher dielectric values obtained suggests their use as a microwave absorbing materials besides being a promising candidates in the electromagnetic shielding applications. Generally, we can conclude that, the complete coating of MZF particles with PPy not only greatly influence the magnetic property but also greatly affected and improved the electrical properties. The ferrites’ preparation method was found not to affect the structural, magnetic or electrical properties owing to the core–shell structure formed.
Summary Two infants presented with amniotic constriction bands (ACB) in the distal third of the forearm. After teeth eruption they developed recurrent skin ulcerations mainly in the distribution of ...the median nerve from digital sucking. Both patients underwent reconstruction with multiple Z-plasties, followed by neurolysis of the ulnar nerve and sural nerve grafting of the median nerve. This neurological complication presented late in ACB as ulcerative lesions and secondary infection from digital sucking on the insensate digits. Thorough physical examination of the extremities at an early stage in children with ACB is essential to exclude an occult neurological dysfunction. Exploration of peripheral nerves is warranted in cases of deep forearm ACB during their soft tissue reconstruction.
The aim of this study was to investigate the use of cement kiln dust (CKD) as a cementitious material in concrete and mortar. CKD was added to concrete and mortar mixtures to study its effect on the ...strength and on the ability of the cover zone to absorb water, an important factor in the deterioration process. Experimental results on compressive strengths, flexural strength and toughness of concrete samples containing CKD are reported. The sorptivity and the initial surface absorption tests (ISAT) of mortars were used to measure the absorption characteristics for different mortar samples containing CKD. It was found that substitution of cement with CKD does not lead to strength gain for all samples studied and proper addition of CKD has no negative effects on strength properties. It is also shown that mortars prepared using suitable amounts of CKD have better absorption characteristics. However, above certain limits, the water absorption of the mortar increased with increasing CKD contents and decreasing mortar strengths.
Various wastes and by-product materials are generated in the Sultanate of Oman including reclaimed asphalt pavement (RAP) aggregate, demolition concrete, cement by-pass dust (CBPD), copper slag, ...petroleum-contaminated soils (PCS), discarded tires, incinerator ash, and others. Recycling of such materials in construction is not practiced. Research data are also minimal into the potential use of selected materials in construction applications. This paper will present the results of several laboratory studies conducted into the use of PCS in asphalt concrete mixtures; on the use of CBPD in soil stabilization and flowable fill mixtures; on the utilization of copper slag and CBPD as cementitious materials; on the use of incinerator ash in cement mortars; and on the use of RAP aggregate in road bases and sub-bases. Laboratory data generally indicate that it is feasible to partially reuse some of these materials in construction provided that economic incentives and environmental concerns are taken into consideration.
This work presents a robust telerobotic system that consists of a real-time vision-based operator hand tracking system (client) and a slave robot (server) which are interconnected through a LAN. The ...tracking system: 1) monitors the operator hand motion and 2) determines its position and orientation which are used to control the slave robot. Two digital cameras are used to monitor a four-ball-based feature frame that is held by the operator hand. To determine the three-dimensional (3-D) position a tracking algorithm based on uncalibrated cameras with weak perspective projection model is used. This allows finding 3-D differential position and orientation of the operator hand. The features of the proposed system are: 1) a metric for color matching to discriminate the balls from their background; 2) a uniform and spiral search approach to speed up the detection; 3) tracking in the presence of partial occlusion; 4) consolidate detection by using shape and geometric matching; and 5) dynamic update of the reference colors. The operator can see the effects of the previous motion which enables making the necessary corrections through repetitive operator hand-eye interactions. Evaluation shows that the static and dynamic errors of the tracking algorithm are 0.1% and 0.6% for a centered workspace of 20/sup 3/ in/sup 3/ that is 40-60 in away from the cameras. Running the tracking algorithm on two PCs in parallel allowed: 1) a parallel image grabbing delay of 60 ms; 2) a stereo matching delay of 50 ms; and 3) a global refresh rate of 9 Hz.
Carcinoid heart disease is a rare condition affecting mostly tricuspid and pulmonary valves causing right-sided heart failure. Surgical valve replacement is the mainstay of treatment when patients ...become symptomatic and/or in the presence of right heart remodeling. We present a case of severe pulmonary valve regurgitation secondary to carcinoid heart disease occurring 4 years after a surgical tricuspid replacement, successfully treated with direct transcatheter pulmonary valve implantation without pre-stenting.
•Carcinoid heart disease is a rare condition affecting mostly tricuspid and pulmonary valves causing right-sided heart failure.•Surgical valve replacement is the mainstay of treatment when patients become symptomatic.•A simplified percutaneous pulmonary valve implantation could be a potentialalternative in high surgical risk patients.
Fresh water is a precious and scarce commodity in all arid regions such as Oman and other parts of the Arabian Peninsula. However, non-fresh water supplies including brackish groundwater and oily ...water that accompanies oil production activities, and treated wastewater exist in abundant quantities in these regions. A flowable fill, also known as a controlled low strength material, is a self-compacted, cementitious material used primarily as a backfill. It is generally a mixture of fine aggregates, small amount of cement, fly ash, and water. This paper discusses the potential use of groundwater and oily production water in flowable fills. The water used in this research work was obtained from four major oil production fields. Cement by-pass dust (CBPD) was used as an alternative to fly ash. Results indicate that the use of non-fresh water will produce lower compressive strength in comparison with tap water. However, all water types would still generate an acceptable 28-day strength requirement of 350–3500 kPa for flowable fills. With the exception of a few mixes, flowable fill blends prepared using brackish groundwater gave higher strength than mixes prepared using oily production water. Generally, there was no appreciable difference in slump values for most of the mixes.
Sea turtles migrate to various habitats where they can be exposed to different pollutants. Bacteria were collected from turtle eggs and their resistance to antibiotics was used as pollutant ...bio-indicators of contaminated effluents. Eggs were collected randomly from turtles when they were laying their eggs. A total of 90 eggs were collected and placed into sterile plastic bags (3 eggs/turtle) during June–December of 2003. The bacteria located in the eggshell, albumen and yolk were examined, and 42% of the eggs were contaminated with 10 genera of bacteria.
Pseudomonas spp. were the most frequent isolates. The albumen was found to be the part of the egg to be the least contaminated by bacterial infection. Bacterial isolates tested with 14 antibiotics showed variations in resistance. Resistance to ampicillin was the highest. The presence of antibiotic resistant bacteria in eggs indicates that the green turtle populations were subjected to polluted effluents during some of their migratory routes and feeding habitats. Scanning electron microscopy revealed that
Salmonella typhimurium penetrated all eggshell layers.
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