Appraisal of Agriglass in Promoting Maize Production Under Abiotic Stress Conditions

An agriglass composition containing different oxides acts as a slow release for macro and micro nutrients and was chosen to improve maize yield under most important abiotic stresses which affecting agriculture development; salinity and drought. A field experiment was performed in salt affected soil (EC =?7.5 dSm^??1) by using different water deficit rates (I1 = 100, I2 = 85 and I3 = 70% of maize water requirements). Irrigation levels were located in main plots. Every main-plot divided into six sub-plots contained glassy fertilizer treatments [F1 = 55 kg fed^?1 with 1/2 mm diameter of agriglass (fed. =?4200 m²), F2 = 55 kg fed^?1 with 1 mm diameter, F3 = 80 kg fed^?1 with 1/2 mm diameter, F4 = 80 kg fed^?1 with 1 mm diameter, F5 = Recommendations of Ministry of Agriculture and F6 = control]. The experimental results demonstrated that, ears, straw, grains and biological yields increased with increasing both water and agriglass rates. Application of agriglass as a slow release fertilizer improved yield more than mineral fertilizer. Some growth parameters, water use efficiency (IWUE), macronutrients concentration and their relations were included. Other studies on residual effect of agriglass and the annual application rates to withstand salinity and drought stress by strategic crops are required.     

Effects of substrate bias voltage on adhesion of DC magnetron-sputtered copper films on E24 carbon steel: investigations by Auger electron spectroscopy

The adhesion strength of copper thin films on E24 carbon steel substrates was studied using the scratch test via the critical load. Coatings were deposited by a DC magnetron sputtering system. All substrates were mechanically polished; some of them were directly coated and others were ion-etched by argon ions prior to deposition process. The effects of substrate negative bias voltage during the film growth were investigated. Experimental results showed that the critical load depended on the bias voltage and that the higher bias voltage, the better adhesion. It was also observed that the deposition rate of deposited films gradually decreased with the increase of the substrate bias voltage. Furthermore, the working pressure during the substrate ion bombardment etching greatly affected the critical load. Scanning electron microscopy was used to observe the scratch tracks to accurately evaluate the critical load. Substrate surface profiles obtained by a mechanical profilometer showed that the critical load increased with the increase of the surface roughness. The analysis by Auger electron spectroscopy revealed that the interface, in case of an unbiased substrate, was relatively narrow and abrupt. However, in case of a bias voltage application, the interface was wider and more diffuse. These results suggest that the mechanisms involved in critical load enhancement are due firstly to the substrate surface roughness and the substrate temperature generated by the ion bombardment, secondly to the physical mixing in the interfacial domain and the densification of the deposited material created by the bias voltage.     

Evaluation of Agriglass as an Environment Friendly Slow Release Fertilizer

Six different agriglass compositions of the (P₂O₅-SiO₂-K₂O) system were prepared with the addition of some oxides; Fe₂O₃, MnO₂, ZnO, CuO. Glasses were synthesized by a melting quenching technique at 1150 ^°C. The chemical activity of glass grains of different diameters (0.5 and 1 mm) was estimated by measuring available K₂O % by a flame photometer, and P₂O₅ % by a spectrophotometer, in conditions simulating the plant root zone by shaking in DTPA solution (NH₄HCO₃-DTPA: ammonium bicarbonate diethylenetriaminepentaacetic acid) for 30 min. The results showed that PS1 glass with main composition (55 P₂O₅, 5 SiO₂, 30 K₂O, 5 Fe₂O₃, 5CuO) wt.%, produced high release nutrient values. The other chemical activity tests were established to evaluate the PS1 glass by shaking in distilled water for 0.5, 1, 2 and 3 hours, and immersion in DTPA solution and 2 wt% citric acid solutions for 1, 2, 3 and 4 months. A greenhouse experiment was performed to evaluate two rates of PS1 agriglass (PS1R1 and PS1R2) compared with the recommended rate of ordinary mineral fertilizers (MF). Although, the effect of MF is higher than both vitreous fertilizer rates in the measurement of 100 grains weight, grains and Stover weight, the application of agriglass with high rate (PS1R2) gave higher results than that of MF in the measurements of ears weight, plant height, and crop weight. It has been found that PS1 glass can be used in practice for maize as an environmentally safe fertilizer.     

Evaluation of the Suitability of Agriglasses Containing ZnO for Plant Fertilization

Six different samples from borosilicate and phosphate glassy systems have been synthesized. Glass batches were prepared from chemically pure materials and melted in platinum or porcelain crucibles and at temperatures in the range 1,000–1,450 °C for 2-3 h until homogeneity was reached. The prepared specimens were annealed at the appropriate temperatures of 380 or 520 °C for the phosphate and borosilicate glasses, respectively. Samples of 2 mm dimensions were tested for dissolution behavior in 2% citric acid solution for 1, 2, 3, and 4 weeks and the released phosphorous and potassium ions (macroelements) and zinc ions (microelement) were measured. Also, Infrared (IR) absorption spectra of the samples were measured before and after immersion in the leaching solution. The experimental results indicate that the release of the macroelements and microelements depends primarily on the composition of the agriglass and the percent of constituent ions and the released ions vary slightly from 1 week to 4 weeks. The IR spectra show characteristic IR absorption bands due to vibrations of collective silicate, phosphate, and borate groups, depending on the agriglass composition and the chains or units seem to be interconnected with each other within the glass network. The interpretation of the dissolution behavior is based on a suggested mechanism for the release of the easily soluble components from the glass specimens. The IR absorption spectra support and confirm the proposed behaviour for the corrosion mechanism.     

Influence of the interface width on the adhesion strength of copper films deposited on negatively biased carbon steel substrates

In order to improve the adhesion of copper films deposited by DC magnetron sputtering on carbon steel substrates, a negative bias voltage was applied to the substrate during the film deposition process. The scratch test was used to evaluate the adhesion strength of the films on the substrates. Chemical element identification and interface width measurement were carried out by Auger electron spectroscopy. The experimental results show that a variation of the bias voltage causes a change in the behaviour of the interface width similar to that of the critical load. The size of the interface width is obtained from Auger elemental depth profiles by measuring the depth of the interface between the coating and the substrate. It had a value of 45 min for an unbiased substrate and increased to 310 min at a bias of 450 V. In the latter case, the interface is relatively wide and the effects of diffusion and physical mixing of materials at the interface become preponderant. Then, the interface width decreased to 130 min at 600 V in which case it gets narrower and the phenomenon of film densification becomes prominent. In all cases, the substrate temperature generated by the bias voltage also has an effect. Moreover, it was observed in this study that the critical load increases with the size of the interface width. As a result, the application of a bias voltage contributes positively to the enlargement of the interface and consequently enhances the adhesion strength.     

Critical condition of DC flashover on a circular sector model

In order to find the electrical size which determined the critical condition of flashover, the authors have examined the propagation of the discharge on surface under DC voltage in a new laboratory model which has a continuous and radial current distribution. This model is a vat having a circular sector form of variable angles, radiuses and depths filled by an electrolyte. The obtained results on this model show that for a given resistivity of electrolyte: if the current distribution in the horizontal plane is uniform according to the sector angle, the applied critical voltage and the critical current per unit of angle (1deg) are constant for all sectors of various angles, if the current distribution in the vertical plane is uniform according to the depth, the critical flashover voltage and the critical current per unit of the electrolyte depth (1 mm) are constant for all the depths. These results lead to the critical conditions of flashover to be determined by the current per unit of angle and per unit of electrolyte depth (A/deg/mm)     

Resistance of pollution in equivalent electric circuit of flashover

In flashover-modelling literature, researchers only take into account, the resistance of the pollution on the insulator, assuming that the current takes part in its totality and that the geometrical shape of its lines in the pollution does not have an influence on the phenomenon. In the paper, and after presentation of the equivalent electric circuit of flashover used in the literature, an experimental study and physical analysis are presented concerning this assumption in two sets of laboratory models: multidirectional models and circular-sector models. The results obtained allow us to confirm first that the form of the pollution and the distribution of leakage current lines are indispensable to flashover modelling; and secondly that flashover criteria and critical conditions in the literature are unjustified.     

Effect of ZnO on the Bioactivity of Hench’s Derived Glasses and Corresponding Glass-Ceramic Derivatives

Some glasses based on Hench’s patented bioglass have been prepared with ZnO replacing Na₂O or CaO in order to investigate their bioactivity in the glassy state or after conversion to their glass-ceramic derivatives. In-vitro investigations of bioactivity of the prepared glass and their glass-ceramics derivatives were carried out by Infrared absorption spectra (IR) of the samples before and after immersion in simulated body fluid (SBF) for different time periods at 37 °C. An X-ray Diffraction (XRD) analysis technique was performed on the glass-ceramic samples to identify the crystalline phases formed during the controlled thermal treatment. Chemical corrosion experiments were also performed to evaluate the chemical behaviour of both glassy and the glass-ceramic derivatives towards SBF. The IR results showed that the amount of the apatite layer formed on the surface of the sample containing ZnO depends on the wt% of ZnO content. The X-ray results indicate that there are two phases formed: sodium calcium silicate and kilchoanite. Weight loss data were observed to change depending on the percent of ZnO and the role of housing of Zn²⁺ in the glass structure. Corrosion behaviour of glass-ceramic derivatives indicates higher durability than in the corresponding parent glasses as expected.     

Shielding Behavior of Gamma-Irradiated MoO<Subscript>3</Subscript> or WO<Subscript>3</Subscript>-Doped Lead Phosphate Glasses Assessed by Optical and FT Infrared Absorption Spectral Measurements

Undoped and MoO₃- or WO₃- doped lead phosphate glasses were prepared by the melting-annealing technique. The glasses were characterized through UV-visible and infrared measurements which were repeated after gamma irradiation. Optical spectrum of binary lead phosphate glass shows distinct ultraviolet bands correlated with unavoidable trace iron impurities within the chemicals used for the preparation of the glasses. UV-visible absorption spectra of MoO₃- or WO₃- doped glasses exhibit additional UV-visible bands which are related to the presence of four oxidation states of the two transition metal (molybdenum or tungsten) ions (Mo³⁺, Mo⁴⁺, Mo⁵⁺, Mo⁶⁺, W³⁺, W⁴⁺, W⁵⁺, W⁶⁺). The extra UV band is related to hexavalent (5d⁰) state while the rest of the visible bands are related to (350–440 nm - trivalent state), (450, 550, 650 nm - tetravalent state) while the broad band centered at about 770 nm (pentavalent state). The intensities of the absorption bands are observed to change with the transition metal content and their valencies. Infrared absorption spectra reveal distinct vibrational bands which are assigned to phosphate groups with sharing of Pb-O vibrations within both the range 460–620 cm^-1 and the range 900–1100 cm^-1 revealing a compact network structure. Gamma irradiation causes a minor increase in intensity of one of the UV band due to suggested photo-oxidation of some trace ferrous ions to additional ferric ions but the remaining spectral curve remains unaffected which is obviously related to some shielding effects of heavy atomic weight of PbO. This heavy metal oxide (PbO) is assumed to retard or prohibit the free passage of free electrons or positive holes generated during the irradiation process.