A comprehensive review of natural fiber reinforced Polymer composites as emerging materials for sustainable applications

The increasing depletion of fossil fuels and the growing demand for eco-friendly materials have driven the development of natural fiber composites. These composites possess desirable mechanical properties such as eco-friendliness, good thermal characteristics, lightweight, lower production costs, and renewability, making them preferable to synthetic composites made from glass and carbon. The use of natural fiber composites in various industries such as automotive, construction, defense, and infrastructure has grown due to their ability to reduce greenhouse gas emissions. This review examines recent advancements in natural fiber reinforced Polymer composites (NFRPCs), focusing on the diverse types of natural fibers such as flax, hemp, and ramie used as fillers and various plastics employed as Polymer matrices. It also discusses the pre-processing treatments of natural fibers, including chemical, mechanical, and thermal methods, which are crucial for optimizing NFRPC properties. Additionally, the review discusses both conventional and advanced manufacturing techniques and the key factors influencing the production quality of NFRPCs and their diverse industrial applications. However, a major challenge for NFRPCs is the hydrophilic nature of plant fibers, which limits bonding with the Polymer matrix and results in poor mechanical characteristics. Future research should focus on developing effective and affordable surface modifiers, dispersion aids, or coupling agents and on understanding the bonding mechanisms at the interface. Nanoscale interfacial characterization is crucial for exploring stress transfer, interfacial penetration, and adhesion. Incorporating nano reinforcements such as graphene and carbon nanotubes can enhance interfacial properties but preserving the intrinsic strength of modified fibers remains a challenge. Eco-friendly in-situ Polymer coatings such as polydopamine and polypyrrole offer potential solutions.Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/FT/2025/004); Univerzita Tomáše Bati ve Zlíně, UTB; TAČR TREND, (FW10010536)Tomas Bata University, Zlin, Czech Republic [IGA/FT/2025/004]; TACR TREND [FW10010536

Capping agent control over the physicochemical and antibacterial properties of ZnO nanoparticles

Life science research has largely benefited from the use of nanoparticles (NPs), yet fundamental issues such as colloidal stability and control over NP size and shape affect NP properties and functions in biomedical applications. Here we show that including capping agents directly into zinc oxide (ZnO) NP synthesis can lead to better control of these properties and their enhanced functionality. A systematic study of the influence capping agents has on the physicochemical and antibacterial properties of ZnO NP synthesized using the microwave (MW)-assisted polyol method is presented. Primary NP size (10–20 nm) was controlled by zinc precursor concentration, and NP shape was influenced by capping agent type. Capping agents enabled control over the surface charge and water interaction properties of ZnO for further investigations involving bacteria. The superior antibacterial effect was observed using positively charged, hydrophilic HMTA-capped ZnO, yet negatively charged hydrophobic OA-capped ZnO still exhibited an antibacterial effect. These observations suggest different underlying mechanisms, and we discuss these differences with particular reference to the specific surface area of ZnO, and how this is key to bacteria-nanoparticle interactions. Appropriate selection of capping agents is crucial for the synthesis of potent ZnO NPs intended for antibacterial applications, specifically for combating resistance.European Commission, EC; TAČR, (TM03000033); US-UK Fulbright Commission, (2022-21-1, RP/CPS/2024-28/007); US-UK Fulbright Commission; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (CZ.02.01.01/00/22_008/0004596 - SenDiSo); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; České Vysoké Učení Technické v Praze, ČVUT, (SGS23/166/OHK4/3T/13); České Vysoké Učení Technické v Praze, ČVUT; Grantová Agentura České Republiky, GAČR, (24-10607J); Grantová Agentura České Republiky, GAČRTACR; European Union; Grant agency of the Czech Republic; CTU; Fulbright Commission in the Czech Republic; Ministry of Education, Youth and Sports of the Czech Republic; [TM03000033]; [CZ.02.01.01/00/22_008/0004596-SenDiSo]; [24-10607J]; [SGS23/166/OHK4/3T/13]; [2022-21-1]; [RP/CPS/2024-28/007

RheoTack evaluation of detaching behavior of silicone-based pressure sensitive adhesives for transdermal therapeutic systems

This study focuses on applying the RheoTack method to assess the detaching behavior of transdermal therapeutic systems (TTS), which represent skin-applied medications comprising a drug-loaded pressure-sensitive adhesive (PSA) and a flexible backing layer. The RheoTack method provides detailed force-retraction displacement-curves (F-h-curves) that reveal the influence of chemical structure and resin content on PSA deformation and fibril formation. To compare various rod geometries (flat rods with diameters of 5 mm and 8 mm, and a spherically rounded rod with a contact area of 5 mm2), the force-retraction displacement curves were normalized to account for the effective contact areas. The flat and spherical rods led to completely different F-h-curves as well as different failure and tack behaviors. Furthermore, the adhesion formation between the TTS with flexible backing layers and rods during the dwell phase occurs in a different manner compared with rigid plates, particularly for flat rods, where maximum compression stresses occur at the edges and not uniformly over the cross-section. Measurements of F-h-curves were performed with retraction speeds of 0.01, 0.1, and 1 mm/s. The increase in retraction speed increased the stiffness from 250 to 1200 N/m for non-amine-compatible PSA measured with a rod of 8 mm. RheoTack measurements were performed with a dwell time of 1 s, which is consistent with ASTM D2949. However, the TTS was in the adhesion-establishing compression phase for 3 s at 1 mm/s and for 30 s at 0.01 mm/s. Thus, the approach to follow ASTM D2949 has to be reconsidered for testing TTS materials.Graduate Institute Bonn-Rhein-Sieg University of Applied Sciences; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2024–2028/005, RP/CPS/05/2024–28); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Bundesministerium für Bildung und Forschung, BMBF, (03FH039PX5); Bundesministerium für Bildung und Forschung, BMB

Evaluating surface quality of heterogeneous surfaces produced by non-conventional machining technologies: Methodological advances and challenges

This paper is focused on the evaluation of heterogeneous surface quality. In the realm of scientific practice, there exists a significant inconsistency in the methodologies employed to investigate heterogeneous surfaces produced by non-conventional machining technologies. Traditional approaches are inadequate for these types of surfaces due to the presumption of surface roughness homogeneity, which does not account for the complexities and variations inherent in heterogeneous surfaces. The utilization of unsuitable assessment methods can significantly hinder the research and development efforts related to these advanced technologies, potentially stalling innovation and the optimization of machining processes. However, through an initial investigation of roughness data obtained from heterogeneous surfaces, discernible patterns have emerged. These patterns suggest a promising opportunity for the development of a coherent and standardized approach to surface quality assessment. Such an approach would enhance the accuracy and reliability of evaluations, thereby supporting the continued advancement and refinement of non-conventional machining technologies. The findings underscore the necessity for a shift towards more sophisticated and tailored assessment methods that can accommodate the unique characteristics of heterogeneous surfaces

Prediction of biaxial properties of elastomers and appropriate data processing

An equibiaxial tension test could be necessary to set up hyperelastic material constants for elastomers exactly. Unfortunately, very often, only uniaxial tension experimental data are available. It is possible to use only uniaxial data to compute hyperelastic constants for a hyperelastic model, but the prediction of behavior in different deformation modes (as is equibiaxial or pure shear) will not work correctly with this model. It is quite obvious that there is some relation between uniaxial and equibiaxial behavior for the elastomers. Thus, we could use uniaxial data to predict equibiaxial behavior. If we were able to predict (at least approximately) equibiaxial data, then we could create a hyperelastic model usable for the general prediction of any deformation mode of elastomer. The method of the appropriate processing of experimental data for such prediction is described in the article and is verified by the comparison with the experiment. The presented results include uniaxial and equibiaxial experimental data, the created average curve of both the deformation modes, and the predicted equibiaxial data. Using Student's t-test, a close coincidence of the real and predicted equibiaxial data was confirmed.Tomas Bata University in Zlin [IGA/FT/2024/002]Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/FT/2024/002

Critical Entities Resilience Assessment (CERA) to small-scale disasters

Since 2022, there has been a significant increase in the importance of critical entities in terms of critical infrastructure protection. The adoption of the Critical Entities Resilience Directive must in EU member states ensure not only the protection of critical infrastructure, but also a sufficient resilience level of the entities themselves. This directive obliges critical entities to take measures to increase their resilience but does not provide any methodological support. A necessary starting point for fulfilling this obligation is knowledge of the current state of critical entities resilience to small-scale disasters. The results of the resilience assessment will then enable critical entities to identify vulnerabilities on the basis of which adequate technical, security and organisational measures can be defined. Therefore, this article presents an entirely new semi-quantitative method, CERA, which has been developed for the comprehensive assessment of entity and infrastructure resilience of critical entities. At the core of this method is a procedure that allows critical entities to self-assess their internal resilience through individual factors, which are defined in detail in this article. In order to facilitate the assessment process, the authors of the article have created the CERA Support Tool, which is supplementary material to this article. The Results section of the article also includes a presentation of a practical application example of the proposed procedure.Ministry of the Interior of the Czech Republic [VK01030014]; VSB - Technical University in Ostrava [SP2024/039]Ministerstvo Vnitra České Republiky, (VK01030014, SP2024/039

The "dark side" and negative consequences of cryptocurrencies usage for unethical purposes as barriers to invest in Middle East and African (MEA) countries

Purpose: This paper aims to unveil the darker side of cryptocurrencies by delving into its role as an obstacle to investments in Middle East and African (MEAs) countries, unravelling the challenges involved. Indeed, despite the rise of blockchain-related technologies, specifically cryptocurrencies, having undeniably unlocked new avenues for business and society, crypto for venture funding purposes may exhibit a "dark side" due to their use for unethical purposes, for example, money laundering or terrorism financing, largely diffused in certain areas of MEA countries. Design/methodology/approach: Through an explorative research design, using a mix of techniques based on both qualitative and interpretive methods, we conducted in-depth interviews among 33 European managers of companies engaged in MEA markets or aspiring to invest in such foreign markets, to analyse their thoughts, perceptions and possible strategies concerning the management of the "dark side" of cryptocurrencies in MEAs.FindingsOur investigation unearthed seven pivotal issues, which manifest as significant barriers related to the ambivalent use of crypto for funding projects, encompassing seven important consequential elements: (1) lack of knowledge about the technology's potentialities; (2) perceptions of crypto technology's ambivalence; (3) reputation and image consequences; (4) uncertainty about the destination of the invested funds; (5) decreased attractiveness of MEAs; (6) competition and market; and (7) lack of control and regulation. We grouped these into technology-related, business-related and legal- and policy-related barriers. Such findings underline the probable decrease in attractiveness of MEAs in terms of investments, together with the triggering factors and potential strategic solutions to mitigate such circumstances. Research limitations/implications: Future studies could explore a broader sample of managers since we only considered the perception of European managers operating in companies that invest (or are intending to invest) in MEAs. Moreover, future research may extend the analysis to MEA-native companies or those engaging in reciprocal exchanges with Western countries. Practical implications: Practically, our findings suggest several elements in which to intervene to mitigate managers' negative perception of the unethical use of cryptocurrencies in MEAs and to support CEOs' and CFOs' strategies, together with requirements to ensure the unaltered attractiveness of investments in an otherwise thriving region of the world, without overlooking the protection and safeguarding of investments and the health of the market and competition. Furthermore, a call for future research in this domain, along with at least minimal regulatory mechanisms, clearly emerges. Social implications: Our findings underline the social challenges associated with the perception and acceptance of cryptocurrencies in these contexts, influencing cultural and social dynamics. Moreover, the identification of these barriers could underscore the significance of awareness of and education on blockchain technology and cryptocurrencies within society, including implications for policymakers. Originality/value: Despite prior investigations into the negative effects of cryptocurrencies as a form of venture funding, no studies to date have examined managers' perceptions by focusing on possible barriers to investment in MEA countries due to the unethical usage of crypto. Importantly, this paper unravels the unexplored complexities of crypto's impact on ethical investments in MEAs, showcasing an original perspective

Analysis of measurement uncertainties in mechanical production and subsequent use for process stability control

In the current industrial environment, where quality is a key factor in competitiveness, the measurement and control of the stability of production processes plays a vital role. This work focuses on the analysis of measurement uncertainties in mechanical production and their subsequent use for process stability control. Measurement uncertainties are an inherent part of any measurement system, and their understanding and proper management are necessary to ensure the accuracy and reliability of production processes. The MSA (Measurement Systems Analysis) method enables the assessment of the capability of measurement systems and the identification of sources of variability. Emphasis is placed on the standard uncertainties of types A and B and the ways in which they affect the measurement process. The work also includes a description of the implementation of statistical process control (SPC) and its importance in maintaining a stable production process. SPC makes it possible to continuously monitor production processes and quickly identify deviations, leading to timely corrections and minimization of defects. To achieve these goals, quality tools such as the Ishikawa diagram, histogram, and Pareto diagram are used. This work provides a comprehensive view of the importance of measurement and data analysis in ensuring stability and quality in manufacturing processes

Utilization of polyethylene waste for designing foamy oil sorbents

Recycling low-density polyethylene (LDPE) in its original form presents several challenges, including limited interest from converters, poor market demand for recycled products, higher sorting and cleaning costs, and reduced quality in the final products. It happens because recycled LDPE often exhibits lower mechanical strength and diminished aesthetic appeal than its virgin counterpart, making it rarely suitable for its original purpose, especially in packaging. Therefore, new applications for LDPE recyclates are needed to overcome these barriers and extend the material’s lifecycle. One such solution involves converting LDPE waste into foamy sorbents for water purification. The presented study investigated two strategies for recycling LDPE waste by exploring the potential of the modified waste to remove free oil spills. The first approach involves preparing and characterizing robust, mechanically stable foams using recycled waste from LDPE packaging. The process is based on parallel foaming and crosslinking of LDPE by peroxides. The final foamy structure (Foam 1) possesses around 75 vol% of pores (46 vol% open pores) and rapidly absorbs various organic liquids quickly (hexane, diesel oil, crude oil) in multiple cycles. The second target deals with the screening, testing, and characterizing of LDPE-based foams that were initially used for various packaging and deposited as waste to explore their potential free oil sorbents. The foam that was used in this study has a significantly porous structure, having 96 vol% of pores and more than 89 vol% open pores (Foam 2). Whereas the sorption capacity of Foam 1 was 4–5 g/g, depending on the type of oil, Foam 2 absorbed those oils in the range of 8–12 g/g. The Foam 1 showed significantly better stability over multiple cycles and better mechanical performance.Qatar University [GSRA9- L-1-0520-22027]; Qatar National Research Fund under its GSRAQatar National Research Fund, QNRF, (GSRA9- L-1-0520-22027

Intellectual model for analyzing and anaging patient trust in medical staff of primary healthcare institutions

In the work, research was conducted on the development of an intellectual analysis model for determining the level of trust of patients in the medical staff of a primary medicine institution, for effective strategy and management on the example of the countries of the Visegrad Group (Czech Republic, Hungary, Poland, Slovakia). The research uses modern knowledge collection and presentation methods, applied in fuzzy set theory, system analysis, and expert evaluation. The main value of the model lies in the fact that it examines the question of evaluating the effectiveness of the management of primary medicine medical institutions, taking into account the level of trust of patients in the medical staff. The model provides an opportunity to comprehensively analyze the region and develop recommendations for state authorities to create strategies for improving the quality of medical medicine in outpatient facilities. At the level of primary medicine institutions, managers should develop strategies to create conditions in which patients' trust in medical personnel will grow. The developed model was verified and tested on real data of primary medicine patients in the countries of the Visegrad Group. An example of evaluation on fragments of data in four regions is illustrated