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The disintegration of Cu metal in 1 mol/L HCl and the mitigating effect of the expired Ceftazidime antibiotic were studied. The inhibition efficacy of Ceftazidime depends on its concentration in the medium. The mitigation efficacy increases from 77.7 to 94.2%, as the Ceftazidime concentration increases from 50 to 300 ppm in the corrosive medium. The polarization results confirmed that the antibiotic acts as a mixed-type inhibitor. The adsorption of the antibiotic on the Cu surface belongs to Timken's model. The adsorption constant, Kads, and the standard free energy change ΔGo were estimated. The adsorption of Ceftazidime drug follows a physical-type. Scanning microscopy (SEM) and energy dispersing X-ray (EDX) techniques demonstrated that the expired antibiotic molecules are firmly adsorbed at the copper surface. Electrochemical modulation (EFM), and polarization tests are in good agreement with the weight lack method.

Conventional water-softening processes usually involve the exchange of Na+ ions for Ca2+ and Mg2+ using commercial or synthesized ion exchangers. The differences in chemical compositions of the ooids can be attributed to the formation in different environments. In this paper, ooid grains form inside assembled semi-pilot softening unit through a continuous chemical process involving reaction between bicarbonate ions and added lime using natural seawater. Our sample of Mediterranean seawater has low Mg2+/Ca2+ ratio (1.98%) within the range chemically favorable for precipitation of low-Mg calcite ooids. Precipitation of calcite occurs around pure quartz sand grains which act as nucleation points (the bed required for sand vessel is 1.65 l). The shape of the sand grains controls the overall external morphology of the resulting ooids; they vary in size from 0.5 to 3.0 mm and have a high degree of polish due to surface abrasion caused by continuous agitation inside the softening system. Calcite ooid grains (1.53 kg) formed within the seawater-softening unit every 18 days have many of the ooid features formed in marine environments. Ooids grow to a significant size, at a rate of about 0.17 mm of one layer thickness per day inside the softening unit. The average weight percent of calcite precipitate is 35.48% after 18 days, at 10 °C, 60 l/min and pH 9.0. The pellets comprise mainly CaCO3 and SiO2 and some metal ions which may substitute for calcium ions in calcite are present only in trace amounts of the total composition.

PurposeTo evaluate effect of water storage on micro-shear bond strength of adhesives to class I cavity-bottom dentin using two types of composites resin.Materials and methodsNinety teeth were divided into three groups I,II&III (thirty molars each) according to the adhesive used, either total-etch 2-step (Adper Single Bond, 3M ESPE), self-etch 2-step(Clearfil SE Bond, Kuraray), or self-etch 1-step(Futura Bond, Voco) respectively. Each group was subdivided according to type of composite restoration used, either Hybrid (Clearfil APX, Kuraray), and Packable (Filtek P60, 3M ESPE). All teeth were thermocycled for 500 cycles,and subjected to occlusal load cycling for 120.000 cycles corresponding to 6 months clinical use. Bonding effectiveness was assessed by micro-shear bond strength test (μSBS) after 1 day, 3 months, and 6 months water storage.ResultsThe mean μSBS values (±SD) for Subgroup IA(SB2-APX) were 32.58 ± 1.416, 31.820 ± 2.119, and 30.910 ± 1.393 MPa after 24 h, 3 month, and 6 month respectively; while for Subgroup I B(SB2-P60) were 31.960 ± 1.659, 31.350 ± 1.765, and 30.380 ± 1.773 MPa respectively. Subgroup II A (CSE-APX) recorded 37.28 ± 1.061, 36.77 ± 2.32, 36.21 ± 1.964 MPa, while Subgroup II B(CSE-P60) recorded 37.0 ± 2.115, 36.460 ± 1.727, and 36.080 ± 1.910 MPa after 24 h, 3 month, and 6 month respectively. Subgroup III A (FB-APX) showed 30.550 ± 2.088, 26.890 ± 1.533, and 21.590 ± 1.784 MPa, while subgroup III B (FB-P60) showed 29.790 ± 1.172, 25.960 ± 2.672, and 21.410 ± 2.126 MPa after 24 h, 3 month, and 6 month respectively.ConclusionTwo-step Total-etch and Two-step self etch adhesives showed better tolerance to water storage compared to One-step self-etch adhesive. However, the type of composite restoration had no significant effect on the microshear bond strength of dental adhesives.

Wool yarns are dyed with natural colouring matter that is extracted from cochineal, turmeric and madder, and mordanted with different mordants by using the exhaustion method. Many measurements of mordanted dyed wool samples have been carried out after exposure to air and light for different periods of time in the time frame of one year in an urban area (Helwan city). The variables that are measured include changes in colour and physical properties (tensile strength, tenacity and elongation) of mordanted dyed wool samples. Also, air pollution in Helwan city is determined by studying suspended and deposited particulate matter and sulpher dioxide concentrations.

The dyeing of acrylic fabrics using C.I. Astrazon Basic Golden Yellow GLE is studied with both conventional (CH) and ultrasonic (US) techniques. The factors that affect dyeability, such as dye bath pH, US power, dyeing time and temperature, are studied. The colour strength values obtained are found to be higher with US than CH heating. Also, the fastness properties of the dyed fabrics are determined with. A comparative study using x-ray and scanning electron microscope (SEM) that is implemented on samples to explain for the better dyeability of acrylic fabrics with the US method. Dyeing kinetics and the time/dye-uptake isotherms reveal enhanced dye-uptake in the second phase of dyeing. The values of the dyeing rate constant, half-time of dyeing and standard affinity, and US efficiency are calculated and discussed.

PurposeTo explore the use of power ultrasound as an environmentally friendly heating technology for the pre‐treatment of linen fibres with sodium perborate as the halogen free oxidising agent and to study the impact of this process on its dyeability with reactive dyes.Design/methodology/approachExploiting power ultrasound in the wet processes of linen fibres was made in two steps, i.e. ultrasonic pre‐treatment with sodium perborate followed by ultrasonic dyeing with reactive dyes. Therefore, comparative studies between conventional and ultrasonic techniques as well as the different factors that may affect these processes were investigated. The effect of the pre‐treatment on fibre fine structure using X‐ray diffraction technique was also investigated.FindingsThe results of the increase of whiteness index indicate that ultrasonic pre‐treatment was better at all studied treatment times and at low temperature. X‐ray diffraction studies on blank, ultrasonically and conventionally pre‐treated linen fibres have shown 70.41, 67.51 and 64.90 per cent crystallinity, respectively. The dyeing of the pre‐treated fibres with Reactive Red 24 was simultaneously carried out under both ultrasonic and conventional heating conditions to study the effect of dye concentrations at different dyeing temperatures. The colour strength values obtained for the dyed samples using ultrasonic at 50°C were slightly higher than those obtained using conventional heating at 80°C. Ultrasonic enhancement in the pre‐treatment and dyeing in terms of the percent increase of colour strength of the dyed fabric was estimated to be 157.94 per cent higher than that of conventional heating method. The results of wet fastness properties of the dyed fibres using ultrasonic revealed improvement relative to those obtained using conventional heating method.Research limitations/implicationsThe improved wet processes of linen fibres suggest further investigation to exploit power ultrasound in the wet processes of cellulosic fibres at low temperature using different classes of halogen free bleaching agents and dyeing with different classes of heat‐requiring reactive dyes. Also, this work may inspire the synthesis of new generation of heat‐requiring reactive dyes.Practical implicationsThe work presented has significant potential industrial application for cleaner production in textile industries.Originality/valueThe present study of linen pre‐treatment with non‐toxic total chlorine free oxidising agent and its dyeability with reactive dyes using power ultrasound is novel and could be used in the wet processes of linen fibres.

Thin films of cobalt–nickel alloys were galvanostatically deposited onto steel substrates from gluconate baths. Cathodic polarization curves were determined for the parent metals and Co–Ni alloy. The effects of bath composition, current density and temperature on cathodic current efficiency (CCE) and alloy composition were studied. The deposition of Co–Ni alloy is of anomalous type, in which the less noble metal (Co) is preferentially deposited. The CCE of codeposition is high and increases with increase in temperature and current density, but it decreases as the [Co2+]/[Ni2+] ratio in the bath increases. The percentage of Co in the deposit increases with increasing cathodic current density, temperature and increasing Co2+ ion concentration. The structure and surface morphology of the deposit were studied by XRD, ALSV and SEM. The results showed that the alloys consisted of a single solid solution phase with a hexagonal close packed structure.

An alkaline bath containing CoSO4 · 7H2O, ZnSO4 · 7H2O, Na2SO4 and NH2CH2COOH is proposed for the deposition of thin layers of Zn–Co alloys onto steel substrates. Electrodeposition was carried out at 0.216–1.080 A dm−2, pH 10 and 10–55 °C. The influence of bath composition, current density and temperature on galvanostatic cathodic polarization, cathodic current efficiency and alloy composition was studied. Different proportions of the two metals were obtained by using different deposition parameters, but at all Zn(II)/Co(II) ratios studied, preferential deposition of zinc occurred and anomalous codeposition took place. Increasing the bath temperature enhanced the cobalt content in the deposit. X-ray diffraction measurements indicated that the phase structure of the deposits was controlled by the applied current density. The Co5Zn21 phase was formed at low current density, while the CoZn13 phase was formed at high current density. The potentiodynamic dissolution of the coatings showed that they contained Zn–Co alloy of different content and structure.

Egyptian cotton straw powder was acid hydrolized in presence of coal tar phenols fraction (b.r. 170–185°C) to give the phenols‐furfural resin. Homopolyepoxy resin was prepared via condensation of epichlorohydrin with phenols‐furfural resin. Similarly copolyepoxy resin was also prepared from epichlorohyhdrin, phenols‐furfural resin and prepared bisphenol A based on coal tar phenols fraction. A study of curing these epoxy resins at 170–185°C with phthalic or maleic anhydride also curing at room temperature with amine was carried out. Also the effect of the addition of kaolin as a filler was investigated to find the optimum condition which allow the cured resin to act as wood adhesive. The obtained results were comparable with those of some commercial adhesives.

Phenols‐furfural resin (analogous to novolake type phenol‐formaldehyde) was obtained from condensation reaction between cotton straw powder and phenolic product in presence of an inorganic acid. The optimum conditions for resin formation were confermed by infrared spectra and its characteristics were determined.

Effects of transport phenomena, including those of viscosity, heat conduction and radiation, are studied for point explosions in perfect gases in plane, cylindrical and spherical geometries. Radiation is considered to be of the diffusion type, while the transport coefficients are taken as proportional to appropriate powers of temperature. These powers are determined by the conditions leading to self-similarity. The structure of self-similar flow fields is then fully determined for different values of specific heat ratios and Reynolds numbers.