PREDICTIVE MATEHMATICAL MODEL FOR ABSORBANT SUBSTRATE ACHIEVEMENT, THROUGH ELECTROSPINNING PROCESS

The new generations of wound dressings aim to create an optimal environment that allows epithelial cells to move easily in order to support regeneration. Such optimal conditions include a humid environment around the wound bed, efficient oxygen circulation to help regenerate cells and tissues, and low bacterial contamination. Composite matrices have several layers and can be used as primary or secondary dressings. Most composite dressings have three layers, respectively a semi-adherent or non-adherent layer, an absorbent layer, and a bacterial barrier layer. A method to obtaining these materials, which can be assimilated to layerby- layer deposition, or which can be operated in this regime, is represented by electrospinning. However, the deposition technique by electrospinning on textile surfaces (fabrics or nonwovens) raises some problems related to the electrostatic behaviour of textile fibres with dielectric properties. In this case, the characteristics of the jet are affected directly proportional with the thickness of the textile material, resulting in defects of nano- or micro-fibrillar deposition, such as unevenness and/or sputter (formation of drops, which are deposited in mixture with electro spun fibres). The article presents a mathematical model that predicts the diameter of the fibres in the composition of the absorbent layer of the multilayer matrix structure for the treatment of burns or gunshot wounds, taking into account the nonlinear relationships between the parameters explained above and specific theories of electrodynamics for thin profiles (for instance, those used in aeronautics) for the prediction of the behaviour of the electrospinning jet.

Improvement of CISSe / CdS / ZnO Structure Performance by SCAPS-1D.

This manuscript presents an optimization of the performances of the CISSe/CdS/ZnO structure. 12 tests were performed for each layer on thickness, gap energy and temperature using SCAPC-1D. Numerical data were compiled with the open circuit voltage, the short circuit density, the fill factor and the efficiency. The results obtained are confirmed with the measurements illustrated in the literature. The analyses indicate a progressive improvement in the performance of the structure for each test; an efficiency of 28.8 % was recorded for the CISSe layer while 30.07 % as an efficiency for CdS and 31.47 % for the absorbent layer. On the other hand, an open circuit voltage does not exceed 1.37V for the whole structure.Thus, these results are satisfied and encouraged.

Effects of wetting and compression/recovering time on the compressionalbehaviour of sanitary napkin layers

Sanitary napkins are technical textile products which are used by women. They are designed as layered structures to fulfil several end–use properties at the same time. One of the most important properties of sanitary napkins is absorption property and this is widely studied in the literature. On the other hand, formability and sensorial comfort of sanitary napkins are of great importance but they are ignored during scientific researches. During daily life, women sit or sleep for certain time intervals and their sanitary napkins are exposed to compressional forces. If the sanitary napkin will squeeze and not recover, this can result with poor sensorial comfort and low formability. Also, wetting of sanitary napkins during usage can worsen the compressional properties. Therefore in this study, effect of wetting and compression/recovering time on the compressional behaviours of sanitary napkins was evaluated. Study was focused on separate sanitary napkin layers in order to detect the most problematic layers. Two compression times and four recovering times were applied to samples for compression tests. Also, sanitary napkin layers were characterised by scanning electron microscopy, unit mass, thickness and bending measurements. According to results, top sheet layer was the most compressible layer in dry and wet states. This is expected to give a soft and resilience sense to the sanitary napkin. Absorbent layer was responsible for low compressibility of sanitary napkins under different compression/recovering times. Bending rigidity of absorbent layer was the highest in dry state but it exhibited a dramatic decrement after wetting

Numerical Analysis of SnO2/Zn2SnO4/n-CdS/p-CdTe Solar Cell Using the SCAPS-1D Simulation Software

This research includes the use of CdTe in the design of a solar cell. The SCAPS-1D computer program was used to simulate thin cell capacity of CdTe/CdS by numerical analysis with the addition of a buffer layer (Zn2SnO4) to enhance cell efficiency. The thickness of the window layer (n-CdS) was reduced to 25nm with the inclusion of an insulating layer of 50 nm thickness to prevent leakage towards the forward bias with respect to the lower charge carriers. As for the absorber layer thickness (p-CdTe), it varied between 0.5µm and 6µm. The preferable thickness in the absorbent layer was 1.5µm. Different operating temperatures (298K-388K) were used, while the highest conversion efficiency (η=18.43%) was obtained with the rest of the solar cell parameters (Voc=0.967 V, Jsc= 26.66 mA/cm2, FF=71.40%).

A PROMISING USE OF COLLAGEN SUBSTANCES IN THE MANUFACTURING OF PERSONAL HYGIENE MEANS

There were performed studies of the interaction of collagen of freshwater fish with water to determine the prospects for its use as an absorbent layer of personal care products, a method for treating freshwater fish skins for obtaining a material with an increased water-absorbing capacity has been developed; thermal stability, allergenic properties of this material have been studied; toxicity tests have been carried out. Methods of thermogravimetry, differential scanning calorimetry, spectroscopy in the visible and ultraviolet region of the spectrum of light waves were used. Allergenicity was determined by the method of cutaneous applications, toxicity - according to State Standards. The most part of moisture was shown to be bound by adsorption or osmotic pathways, only 7% of moisture bound by the samples is retained in the capillaries. The sufficiently high binding energies of about 4 J/mol suggest the ability of the functional groups of fish collagen to create a powerful hydrated membrane. For the loosening of the material, sequential treatment of fish skin in weak solutions of alkalis and organic acids is suggested, after which the swelling capacity reflecting the moisture capacity of the material rises by almost 10 times and amounts to 30 g per 1 g of dry matter. The aggregation of polydisperse systems of processed collagen in the temperature range of 38◦-46◦, which can lead to a decrease in moisture capacity with an increase in temperature to these values, is found. The obtained material has no allergic neither toxic effects. As a result of the studies, it was shown that collagen of freshwater fish, modified by treatment in alkali and organic acid solutions, can be used as a material for the absorbent layer of personal care products under the condition of sparing temperature regimes during their manufacture.

A comparative study on the performance properties of breathable and non-breathable baby diaper back sheet

Disposable diapers are very important in terms of babies’ health because they are in touch with the baby’s skin. Disposable diapers have sheets with different functions from each other. The main layers of disposable diapers are as follows: top sheet, absorbent layer and back sheet. The function of the top sheet is to pass the liquid to the lower absorbent layer whereas the function of the absorbent layer is to absorb the liquid. As for the back sheet, this layer keeps the liquid inside and prevents it from leaving the diaper. The back sheet is usually a nonwoven/ polyethylene (PE) film composite. Considering the babies’ health, breathable back sheets are mostly used in baby diapers to keep the skin drier. These have a positive effect on the baby’s skin, especially in terms of occlusion, diaper dermatitis. In this study, the performance properties of some commercial baby diaper back sheet layers have been investigated. For this purpose, weight, thickness, air permeability, water vapor permeability and water resistance tests were applied to back sheet samples with different fabric mass as breathable and non-breathable films. All back sheet samples are SMS nonwoven/ polyethylene (PE) film composites. Breathable samples have a larger fabric mass than non-breathable samples. For breathable samples, while increasing mass, air permeability and water vapor permeability decrease, water resistance increases. On the other hand, the same tendency is not seen in non-breathable samples. Breathable samples have higher air permeability, water vapor permeability, water resistance, and bursting strength than non-breathable samples. Consequently, the using of a baby diaper containing breathable back sheet is more proper in terms of baby’s skin health.