Explore the vast range of titles available.

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1186/s44147-024-00401-1.

This study proposes a modification for the current design approach for square and rectangular silos that accounts for silos’ wall flexibility. First, the authors investigated the effect of wall stiffness symbolized by the wall width-to-thickness ratio (a/t) and silo’s dimensions, on the wall-filling pressure using a recently validated 3D finite element model (FEM). The model was then employed to predict the pressures acting on silos’ walls accounting for the stress state in stored granular materials. Most design formulas and guidelines assume silos’ walls to be rigid. This assumption is acceptable for the case of rigid wall concrete silos; however, it is questionable for semi-rigid, flexible wall metal silos. Consequentially, it is crucial to determine the minimum wall stiffness necessary to secure the applicability of the current design rigid wall assumptions and to propose a way to deal with semi-rigid and flexible walls. To this end, several wall pressure distributions that correspond to filling steel silos with varied wall thicknesses were studied. A new adjustment to the Janssen technique was proposed for a better estimate of the wall-filling pressures for square and rectangular silos. In the case of prismatic silos, the Eurocode uses the Janssen equation together with an equivalent radius of a corresponding circular silo (with the same hydraulic radius) to determine the wall pressure. This method predicts pressure values that are practically accurate for rigid-wall silos, but its accuracy decreases for semi-rigid and flexible-wall silos. As an enhancement, the Janssen equation was modified in this research to generate more accurate pressure estimates based on the equivalent volume concept. The finite element results of several developed models with the same granular material were compared to the estimations of the newly established approach to verify the broad range of its applicability.

The storage of granular solids in silos provides many interesting problems concerning pressures and flow. It is difficult to obtain repeatable and trustworthy results from either experimental studies or theoretical modelling. Comparisons of the best computational models with experiments are, at best, weak, and provide little assurance of the accuracy of any existing predictive model. The study described here was undertaken to explore the predictions of different models on a set of simplified exercise silo problems. For these problems, no experimental results exist, but simpler tests for truth can be used. This paper reports briefly on an international collaborative study into the predictive capacity of current discrete-element and finite-element calculations for the behaviour of granular solids in silos. The predictions of one research group, however eminent, are often not regarded as authoritative by others, so a commonly agreed theoretical solution of simple silo exercises, using different computational models from research groups around the world, is a valuable goal. Further, by setting the same unbiased exercise for both finite elements and discrete elements, a better understanding was sought of the relationships between the two methods and of the strengths of each method in practical silo modelling. The key findings are outlined here from three of the challenge problems: filling a silo, discharge of granular solid from a flat-bottomed silo; and discharge from a silo with a tapered hopper. Both computational methods display considerable shortcomings for these difficult exercises. Different research groups make widely different predictions, even when the problem statement is very detailed. There is much scope for further comparative studies to identify the reasons why different models based on comparable assumptions can produce such varied predictions.

Background Diabetes Mellitus (DM) is associated with pathological changes in the central nervous system (CNS) and alterations in oxidative stress. The aim of this study was to determine whether dietary supplement with whey protein (WP) could improve neurobehavior, oxidative stress and neuronal structure in the CNS. Methods Animals were distributed in three groups, a control group (N), a diabetic mellitus group (DM) and a DM group orally supplemented with WP (WP). Results The DM group of animals receiving WP had reduced blood glucose, significantly decreased free radical Diphenyl-picrylhydrazyl (DPPH) and lower lipid peroxidation in brain tissue. The WP group of animals showed improvement in balancing, coordination and fore-limb strength, oxidative stress and neuronal structure. Conclusion The results of this study show that dietary supplementation with WP reduced oxidative stress, protected CNS neurons and improved the neurobehavior of diabetic mice.

Optical studies have been performed on amorphous films of the system Ge10Se90-xTex where (x = 20, 30, 40). The study revealed that as the Te content is increased, the optical band gap (Eg) was found to decrease. Photoinduced effects were studied on thin films samples irradiated with either white light or uv light. The shift in Eg due to photoirradiation disappears upon annealing the films at a temperature below the glass transition temperature. The effect of γ-radiation up to 8 kGy on the optical band gap was also investigated, and no detectable shift of the optical band gap was observed. The relationship between the optical band gap and both the average heat of atomization and the average coordination number of the compositions under investigation was studied.

Glass batches were prepared according to the molecular formula: [20 Li^sub 2^O - 31B^sub 2^O^sub 3^ - 34SiO^sub 2^ - (15 - x) NiO - xFe^sub 2^O^sub 3^] where x =0.0, 2.5, 5, 7.5, 10 and 12.5 mol%. In addition a base sample free from Ni and Fe was melted (35 Li^sub 2^O - 31B^sub 2^O^sub 3^ - 34SiO^sub 2^). Both infrared and Mössbauer spectroscopy were used to investigate the structural changes caused by the replacement of nickel by iron cations. The infrared spectra were measured over a continuous spectral range (400 to 2500 cm^sup -1^). They show that the replacement of Lithia by nickel oxide decreases the non-bridging oxygen content. Also, the replacement of nickel by iron decreases the concentration of non-bridging oxygens up to 7.5 mol% and then increases it. From the values of the Mössbauer parameters, all the ferrous cations were found to be in octahedral coordination, while all the ferric ions occupied tetrahedral coordination sites. The ratio Fe^sup 3+^ / Σ Fe^sub total^ increased on replacing nickel by iron up to 7.5 mol % and then became constant. The density increased by replacing nickel by iron up to 7.5 mol% and then decreased.

In Kuwait the Government, represented in its various authorities, has started to import theories and practices from western countries, particularly the United States. [ncluded in these imports, are managerial skills models. From this perspective, the main argument tor this research was whether managerial skills are generic in nature or not. [n other word, the universality and the situational hypothesis were investigated within the context of managerial skills. Furthermore, it aimed at understanding. the components of managerial skills for the industrial manager, through developing a model. This moud consists of three stages. The first stage aimed at measuring the role of demographic variables, national culture, organizational culture, and organizational variables, in determining the required managerial skills for the industrial manager. The second stage aimed to determine the most important factors that lead to acquiring managerial skills. The third stage of the model, aimed at determining the relationship of managerial skills with organizational effectiveness, . and the relationship of independent variables (national culture, organizational culture, and organizational variables) with organizational effectiveness. The sample of the study, represented the industrial companies working in Kuwait, where a questionnaire was distributed to 318 managers from 56 industrial companies (governmental, private, and joint venture), and those managers represent various management levels. The results suggest that managerial skills are not absolutely universal, but there is tendency to universality. The first stage of the model, suggested that the effect of the independent variables is minor. However, organizational culture showed the highest effect, compared with the other variables. For the second stage of the model, it was found that the main four elements that lead to acquiring managerial skills are good quality education, experience acquired through work, the values and ethics of work, and finally, learning from a mentor. Three of these factors are usually acquired before managers are appointed to their positions. In the third stage of the model, it was found that the most important variable which impacts on effectiveness is organizational culture, while the other variables, including managerial skills, have shown a minimal effect. Nevertheless, these variables, combined, have had an affect on effectiveness by a value ofone third. Finally, specific recommendations have been introduced for policy makers and managers to benefit from this study. Furthermore, suggestions are made for future studies.

Nano-ZnMn 2 O 4 and ZnMn 2 O 4 /MWCNT/graphene composites were prepared by solgel and ball-milling methods. The functional properties of the prepared samples were studied by applying various techniques. X-ray diffraction (XRD) Rietveld analysis indicated a single-phase ZnMn 2 O 4 with a partially inverse spinel nanostructure (average size ≈ 7 nm), confirmed by TEM graphs, which revealed the morphology and particle nanosize distribution in samples. The samples were further characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The Gaussian fitting of Zn 2p and Mn 2p narrow XPS spectrum confirmed the cation distribution obtained from XRD Rietveld analysis. The galvanostatic cycling of the pure ZnMn 2 O 4 electrode exhibited higher initial discharge capacity (~ 1978 mAh g −1 ) when cycled at 100 mA g −1 versus Li/Li + . Meanwhile, the cyclic voltammetry tests evidenced the enhanced Li-ion diffusion during the oxidation and reduction processes. The assembled ZnMn 2 O 4 /MWCNT/G cell delivered about 190 mAh g −1 of specific discharge capacity over 100 cycles with 65% capacity retention.

In the current study, a simple dry coating method was utilized to fabricate a super-hydrophobic super-magnetic powder (ZS@BIF) for oily water purification using zinc stearate (ZS) and banded iron formation (BIF). The produced composite was fully characterized as a magnetic sorbent for oily water treatment. The results of X-ray diffraction diffractometer (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and particle size analysis revealed the fabrication of homogenous hydrophobic-magnetic composite particles with core–shell structure. Contact angle and magnetic susceptibility results showed that 4 (BIF): 1 (Zs) was the ideal coverage ratio to render the core material superhydrophobic and preserve its ferromagnetic nature. The capability of the fabricated composite to sorb. n -butyl acetate, kerosene, and cyclohexane from oil–water system was evaluated. ZS@BIF composite showed a higher affinity to adsorb cyclohexane than n-butyl acetate and kerosene with a maximum adsorption capacity of about 22 g g −1 and 99.9% removal efficiency. Moreover, about 95% of the adsorbed oils could be successfully recovered (desorbed) by rotary evaporator and the regenerated ZS@BIF composite showed high recyclability over ten repeated cycles.

Heterogeneous catalysis is widely known as an efficient, clean, and low-cost technology to mitigate the environmental pollution of industrial effluents. This research aimed at optimizing the preparation and characterization of efficient g-C 3 N 4 /Co 3 O 4 nanocomposite for catalytic removal of Rhodamine B (Rh B) dye. The detected XRD peaks for the prepared nano-Co 3 O 4 are matched with the cubic crystal structure. In contrast, the broad peak at 27.3° corresponding to the graphite reflection of hkl (002) was noticeably weakened in the XRD pattern of the g-C 3 N 4 /Co 3 O 4 composite. FTIR spectra of g-C 3 N 4 /Co 3 O 4 nanocomposites revealed the active vibrational modes of each Co 3 O 4 and g-C 3 N 4 component. The microstructure study of g-C 3 N 4 showed the strong interlayer stacking of carbon nitride nanosheets, while the surface morphology of g-C 3 N 4 /Co 3 O 4 nanocomposite revealed a hybrid particulate system. EDS analysis indicated that the spot area of g-C 3 N 4 /Co 3 O 4 confirmed the chemical ratios of carbon, nitrogen, cobalt, and oxygen. BET measurements of g-C 3 N 4 /Co 3 O 4 showed a significant increase in the surface area and pore volume of single components due to the lamination of stacked g-C 3 N 4 nanosheets by the intercalated Co 3 O 4 nanoparticles. The prepared 30% g-C 3 N 4 /Co 3 O 4 revealed the lowest value of E g ~1.2 eV and the highest light absorptivity suggesting strong promotion for the photocatalytic performance under visible light. The maximum photocatalytic activity of about 87% was achieved by 30% g-C 3 N 4 /Co 3 O 4 due to the photonic enhancement, which reduces the recombination of excited electrons. The developed nanocomposite with a g-C 3 N 4 /Co 3 O 4 ratio of 0.3 exhibited high stability in its photocatalytic performance after four recycling times, and a slight decrease of about 7% was estimated after the 5th reuse test.