Fiber statistics of nonwoven materials by SEM images - influence of number of images

Electrospun nonwovens are widely applied in biomedicine and various other fields. For control of the manufacturing process and quality assurance Scanning electron microscopy (SEM) imaging is one standard practice. In this study, statistical datasets of 60 SEM images of three nonwoven samples were evaluated using Gaussian fit to obtain numerical results of their fiber diameter distributions. The question of how much effort is required for acceptable imaging and processing is being discussed. As determined here, for reliable statistics, a minimum surface area of the nonwoven has to be evaluated. The fiber diameter should be in a range of approximately 2 - 3% of the edge length of the square equivalent of the evaluated image area, using sufficiently magnified SEM images, in which the fiber diameter is imaged over at least 30 pixels.

Systematic Studies of Sodium γ-Octyl Aspartate to evaluate its Biodegradation, Surface Parameters, Micellization Aspects and Thermodynamic Properties of its Binary Mixture using Electrolytes

γ-octyl aspartate has been synthesized with 46.2% yield. The optimized conditions for esterification of aspartic acid and n-octanol are 24 hours duration and 1:1 molar ratio of reactants (aspartic acid: n-octanol). FT-IR, 1H NMR and CHNS element analysis techniques are used for structure elucidation of γ -octyl aspartate. Surface/ interfacial studies, micellization aspects, thermodynamic parameters, biodegradability and binary salt behaviour of sodium γ-octyl aspartate have been studied. The CMC of synthesized surfactants was 0.0078 mol/L, whereas minimum surface area per surfactant molecule was calculated as 29.49 Å2m2; calculated aggregation number was 34 and micelle radius (r) found to be 1.40 nm. The degree of counter-ion dissociation (α) was determined to be 0.86. Thermodynamic parameter - standard free energy of adsorption (ΔG0ads) was calculated as -18.70 kJ/mol. The shape of micelle of synthesized surfactant was noticed to be spherical but during binary studies in some cases, it was found to be cylindrical. OECD and Winkler’s method were used to determine biodegradation of sodium γ-octyl aspartate found to be 95.1 %.

OPTIMIZATION OF VESSELS SIZES FROM THE CONDITIONS OF THE MINIMUM HULL SURFACE AREA

The method of optimization of vessels sizes for the reasons of the minimum surface area of the hull is considered. The dependences of the optimal diameter, height and minimum surface area of the tank body on the volume are obtained.

Concept of a Dome House for the Village

The article discusses dome-type houses from the point of view of the concept of energy efficiency, energy saving and multi-functionality. The review of foreign and domestic experience in the design and construction of residential buildings, which are based on the dome cover, is presented. On the basis of this review, it is concluded that there is no unified design, calculation, production and technological regulatory framework. The advantages and disadvantages of dome houses are given. It is noted that the most suitable materials for creating the dome cover is a metal frame and almost continuous glazing. It is revealed that the dome design has a minimum surface area, which makes it possible to save up to 20 % of energy costs for its maintenance. The concept of a dome house combining the function of housing and a "winter garden" has been proposed. In addition, when creating a vegetarian house, other important agricultural and ecological problems are solved, the use of alternative energy sources for example. The article outlines the prospects for the development of this concept.

The Shape-Structure Relation For The Light Construction Membrane Type

In the case of light structures membrane type the form is confused with the structure and vice versa. Thus the analysis process, non-linear type, the one for form finding is also a means of optimizing these structures. To respect the natural principle of minimum it is advisable that the structure’s shape is similar to the minimum surface area. The numerical problem solving is based on using finite elements with constant strain of soap film. Based on these considerations, the paper presents aspects of determining the shape of the membrane structure using finite elements of soap film.

Investigation of the Inhibitive Effect of Hexatriethanolamine Derivatives on Corrosion of Carbon Steel Pipelines in 1M HCI

The corrosion inhibition efficiency of carbon steel pipelines in 1M HCl by the synthesized hexatriethyleneamine derivatives potensiodynamic polarization 30 oC. The results showed that all synthesized inhibitors were good inhibitors and their inhibition efficiencies were significantly increased with increasing concentration. The surface activity were calculated from its surface tension measurements including the critical micelle concentration (CMC), effectiveness of surfactant (π), maximum surface excess (Γmax) and the minimum surface area (Amin).

Effectiveness of some Nonionic Surfactants As Corrosion Inhibitors for Carbon Steel in Hydrochloric Acid Solution

The corrosion inhibition characteristics of the synthesized (I, II and III) nonionic surfactants on carbon steel corrosion in 1 M acid chloride have been investigated at 30 oC by potensiodynamic polarization. The obtained results show that compound I has the best efficiency at concentration 0.08 mmol/L while compound III is the best inhibitor at higher concentrations. The surface parameters of each synthesized surfactant were calculated from its surface tension including the critical micelle concentration (CMC), effectiveness of surfactant (π), maximum surface excess (Γmax) and the minimum surface area (Amin).

Space Structures for Low-stress Environments

This paper examines the criteria for the architectural design of space structures in low-stress environments, where stress-carrying ability is no longer a relevant consideration in the design of the space structure. In such environments, ergonomics and minimum surface criteria can lead to the most efficient design of the space structure. Based on these two criteria, the paper then considers the architectural design of a space tunnel and an interchange station. In direction-controlled artificial gravity environments, the nesting of ergonomic shapes, for minimum surface area, can lead to even more cost-effective design. 3–D computer graphics are used to display the results of this research.