For the mechanical properties of paper, tensile testing has been widely used. Among the tensile properties, the tensile stiffness has been used to determine the softness of low-density paper. The lower tensile stiffness, the greater softness of paper. Because the elastic region may not be clearly defined in a load-elongation curve, it is suggested to use the tensile modulus which is defined as the slope between the two points in the curve. The two points which provide the best correlation with subjective softness evaluation should be selected. Low-density paper has a much lower tensile strength, but much larger elongation at the break. It undergoes a continuous structural change during mechanical testing. The degree of the structural change should depend on tensile conditions such as the sample size, the gauge length, and the rate of elongation. For low-density paper, the tensile modulus and the tensile strength should be independent of each other. The structure efficiency factor (SEF) is defined as a ratio of the tensile strength to the tensile modulus and it may be used a guideline in developing superior low-density paper products.
Chemical additives are used singly or in combination to impart functionality to hygiene paper (suggested). In particular, in the hygiene paper making process, dry strength agent, wet strength agent, softener, and other are widely used. The effects of chemical additives on the softness components were evaluated. In the case of surface softness, there was no change in MMD according to the addition of dry and wet strength agents. The MMD (mean deviation from the average friction of coefficient) was decreased by adding a softener, which is the purpose of its addition to the hygiene paper making process. The softness and wet strength were improved when the wet strength agent was added before the softener. In addition, lotion treatment was applied to the surface of tissue paper. The surface softness component of non-silicone-based lotion was similar or improved, which may overcome the problems of silicon-based lotion.
Surface characterization is important and has many applications in the paper industry. Surface characterization requires both surface roughness and surface friction. The relationship between the two has not been fully established for paper and paperboard. It has been a common practice that only the average property and the standard deviation with the coefficient of variation (COV) are reported for surface roughness and friction measurements. This practice, however, provides few information on surface structure and can lead to wrong judgments because two samples having the same average and the COV can have different physical properties. To avoid such mistake, a new surface characterization method has been developed. To this end, surface roughness- and friction-profiles have been obtained using a latest version of Kawabata surface tester (Model: KES-SESRU, Kato Tech, Kyoto Japan). This new version uses the same stylus for both measuring surface roughness and friction under the same operating conditions. It was found that a correlation between the surface roughness and surface friction was very low. This indicates that they should be independent of each other. Therefore, both should be determined for surface characterization.
Strength, softness, and absorbency have been identified as the key attributes for disposable consumer products such as tissue, towel and diapers. These attributes are generally evaluated subjectively by users. Although subjective evaluation may be necessary for developing such consumer products, it is time-consuming and expensive. More importantly, it seldom provides guidance or direction regarding process control or product development. The main reason is because subjective evaluation is performed after the fact (ex post facto), not before the event (not ex ante). Accordingly, it has been desirable to develop physical test methods to predict in-use performance of a consumer product. In developing physical test methods to link with subjective evaluation, reliable and relevant subjective data is necessary. Developing physical test methods for softness of hygiene paper has been extremely challenging. The objective of this paper is to demonstrate a feasibility of developing physical test methods which can be highly related to subjective evaluation. To this end, it is hypothesized that tissue softness mainly consists of bulk softness and surface softness. It is assumed that the bulk softness should be determined from bulk stiffness which is defined as the slope between the two specified points in a load-elongation curve from tensile testing. It is also assumed that the surface softness should be determined from the surface properties (roughness and friction) from a surface tester (e. g., Model: KES-SESRU. Kato Tech, Japan). It is suggested that the principles used here for developing physical test methods for tissue softness should be also applicable to other physical properties such as strength and absorbency.
Since it was first reported, the novel coronavirus disease 2019 (COVID-19) remains an unresolved puzzle for biomedical researchers in different fields. Various treatments, drugs, and interventions were explored as treatments for COVID. Nevertheless, there are no standard and effective therapeutic measures. Meanwhile, mesenchymal stem cell (MSC) therapy offers a new approach with minimal side effects. MSCs and MSC-based products possess several biological properties that potentially alleviate COVID-19 symptoms. Generally, there are three classifications of stem cell therapy: cell-based therapy, tissue engineering, and cell-free therapy. This review discusses the MSC-based and cell-free therapies for patients with COVID-19, their potential mechanisms of action, and clinical trials related to these therapies. Cell-based therapies involve the direct use and injection of MSCs into the target tissue or organ. On the other hand, cell-free therapy uses secreted products from cells as the primary material. Cell-free therapy materials can comprise cell secretomes and extracellular vesicles. Each therapeutic approach possesses different benefits and various risks. A better understanding of MSC-based and cell-free therapies is essential for supporting the development of safe and effective COVID-19 therapy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.