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Biodegradable Biconstituent Melt-Blown Nonwovens for Air Filtration: Fabrication and Characterization
Melt-blown polypropylene (PP) is extensively used in air filtration due to its low cost, low weight, and easy processing, but there are increasing environmental concerns due to its non-degradability. On the other side biodegradable polymers such as polylactic acid (PLA) present insufficient strength and limited toughness. Polymer blending is a well-known approach to reach optimum properties from at least two polymers. This study aims to produce biodegradable PP-PLA-based filter materials that possess enhanced elasticity and superior filtration performance. The addition of PLA raises the average fiber diameter (AFD), causing the PP-PLA filters to have AFD ranging from 0.73 to 0.91 μm. However, the incorporation of zinc stearate (ZnSt) decreased the melt viscosity, resulting in thinner fiber formations with AFD ranging from 0.6 to 0.75 μm for PP-PLA-ZnSt. The efficiency of the corona-charged optimized sample (double-layer 75PP-25PLA-ZnSt) showed 97.42% particle capture efficiency and filtration performance of 0.12 mmH
2
O
−1
. Despite the presence of hydrophobic surfaces in all filter materials, the addition of ZnSt further improves the resistance to surface wettability. 75PP-25PLA-ZnSt filter material exhibits high stretchability, with a maximum tensile strength of 380 ± 70 kPa. The proposed tricomponent (PP-PLA-ZnSt) approach would be used to reduce the environmental impact of non-degrading polymers.
Graphical abstract
Journal Article
Green tourism business as marketing perspective in environmental management
BACKGROUND AND OBJECTIVES: Environmental guidelines and principles of sustainable development are becoming increasingly popular and are a priority for most business areas. One of the widely developing eco-destinations is green tourism, which is gaining a profitable and priority status, especially for lower middle-income countries. The purpose of the article is to determine the strategic marketing support for the development of green tourism on the example of Ukraine and its regions based on an approach to its assessment in terms of environmental and tourism competitiveness. METHODS: The authors used general scientific and specific methods: comparative, critical and system analysis, synthesis to search and group indicators of ecological and tourism competitiveness. Distance method, ranking, economic and statistical analysis were implemented to analyze the green tourism potential in each region in Ukraine and reveal the leaders and outsiders among them. For the accumulation, processing, visualization of data and forming the matrix of green tourism, based on data for 2015-2019, potential Microsoft Excel, Figma and Canva tools, Harrington scale were applied. FINDINGS: The approach to estimate the green tourism potential based on the ecological and tourism regional competitiveness according to the author's list of 37 indicators were proposed, the matrixes of green tourism potential of Ukrainian regions in 2019 and 2020 were developed, and strategic marketing support according to sustainable development for green tourism business were proposed. Strategic marketing support of green tourism development in Ukrainian regions was defined based on ecological and marketing strategies. CONCLUSION: The author's approach makes it possible to systematically assess the potential of green tourism using up-to-date statistical information. According to the tourism and environmental competitiveness rating, the regions with the most significant and worst potential were found. The positive dynamics of the development of green tourism in 2019-2020 were revealed. The results are the basis for providing comprehensive environmental and marketing support to ensure sustainable development and gain additional competitive advantages in the green tourism business.
Journal Article
A roadmap to using randomization in clinical trials
Background
Randomization is the foundation of any clinical trial involving treatment comparison. It helps mitigate selection bias, promotes similarity of treatment groups with respect to important known and unknown confounders, and contributes to the validity of statistical tests. Various restricted randomization procedures with different probabilistic structures and different statistical properties are available. The goal of this paper is to present a systematic roadmap for the choice and application of a restricted randomization procedure in a clinical trial.
Methods
We survey available restricted randomization procedures for sequential allocation of subjects in a randomized, comparative, parallel group clinical trial with equal (1:1) allocation. We explore statistical properties of these procedures, including balance/randomness tradeoff, type I error rate and power. We perform head-to-head comparisons of different procedures through simulation under various experimental scenarios, including cases when common model assumptions are violated. We also provide some real-life clinical trial examples to illustrate the thinking process for selecting a randomization procedure for implementation in practice.
Results
Restricted randomization procedures targeting 1:1 allocation vary in the degree of balance/randomness they induce, and more importantly, they vary in terms of validity and efficiency of statistical inference when common model assumptions are violated (e.g. when outcomes are affected by a linear time trend; measurement error distribution is misspecified; or selection bias is introduced in the experiment). Some procedures are more robust than others. Covariate-adjusted analysis may be essential to ensure validity of the results. Special considerations are required when selecting a randomization procedure for a clinical trial with very small sample size.
Conclusions
The choice of randomization design, data analytic technique (parametric or nonparametric), and analysis strategy (randomization-based or population model-based) are all very important considerations. Randomization-based tests are robust and valid alternatives to likelihood-based tests and should be considered more frequently by clinical investigators.
Journal Article
Kat's maps
Kat, who loves to make maps of all sorts of places and things, gives a special map to Jack.
Book
Adaptive Model Predictive Control for Intelligent Vehicle Trajectory Tracking Considering Road Curvature
A parametric Adaptive Model Predictive Controller (AMPC) based on Particle Swarm Optimization-Back Propagation (PSO-BP) neural network has been developed in this paper, the primary focus is on improving the trajectory tracking performance of autonomous vehicles under varying road conditions. The PSO-BP neural network is employed for real-time adjustment of the controller's predictive horizon and sampling time. A vehicle dynamics model is established and an improved tracking control algorithm involving road curvature feedforward is proposed. In the design of AMPC, the real-time update of tire lateral stiffness is achieved through the adoption of the Recursive Least Squares (RLS) method, ensuring the precision of trajectory tracking for the vehicle under varying operating conditions. The simulation platform, which combines Carsim and Simulink, was employed for validating the proposed approach. The findings reveal that the proposed controller can promptly adjust the predictive horizon and sampling time according to the vehicle's state. Through the employed estimation strategy, real-time adjustments of tire lateral stiffness are achieved, allowing for dynamic alterations of vehicle speed and front wheel angle in response to road curvature. As a result, this approach significantly enhances control accuracy and lateral steering stability, especially in large curvature conditions.
Journal Article
Cut that out : collage in contemporary design
\"Cut that out is a showcase for all the creative possibilities of collage in contemporary graphic design. Curated by Ryan Doyle and Mark Edwards, who work together as the studio DR.ME, it features the work of fifty leading designers and studios from across the globe ... each of whom uses collage techniques in spectacularly inventive and diverse ways\"-- Page 2 of cover.
Book
Energy-innovation knowledge common connection point management in preventing outbreak of the Covid-19 pandemic in a University
BACKGROUND AND OBJECTIVES: The new wave of the Covid-19 pandemic has complicated the working conditions of higher education institutions in Ukraine. In this regard, saving energy resources of the university offers an opportunity to get out of the crisis. The purpose of the study is to develop a management system for energy complexes with non-conventional renewable energy sources in the context of preventing a new outbreak of Covid-19 pandemic.METHODS: The method of Deutsche Gesellschaft für Nachhaltiges Bauen was used to conduct energy audits, construct energy profiles of university offices. The cluster analysis was used to perform energy certification of university offices according to the indicators of integral energy efficiency potential and the level of annual specific energy consumption. Fuzzy methods made it possible to classify all the buildings into 3 categories (A, B, C) to prioritize their use in the light of Covid-19 pandemic. The system for monitoring the attained level of energy efficiency is based on the use of discriminant analysis.FINDINGS: Implementation of the weighted strategy has proved that the classes will be given online, 23% of all offices. Category A (administrative, technical, service buildings; laboratories with unique equipment with 24-hour service) will be used in a pessimistic scenario (continuation of Covid-19 pandemic). In the optimistic scenario (end of Covid-19 pandemic), by means of the suggested energy efficiency monitoring system, the probability of using category A offices makes 100%, B offices- 50% and C offices - 13%.CONCLUSION: Implementation of the developed energy efficiency action plan will offer the opportunity for the University to use reasonably the common connection point of knowledge management of energy complexes with non-conventional renewable energy sources in the context of preventing a new outbreak of the Covid-19 pandemic. The profitability of implementing a weighted energy efficiency strategy is 15%, with a payback period of 6.7 years for the purchase and installation of non-conventional renewable energy equipment. In the future, it would be advisable to convert gradually all of the remaining 14 university buildings to the autonomous use of non-conventional renewable energy sources, using a common connection point for the knowledge management of the energy complexes.
Journal Article