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

Aktywność mięśni w kontekście optymalizacji ergonometrii miejsca pracy pracowników administracyjnych podczas korzystania z komputera

Background. In the prevalent sedentary work environment, where administrative professionals spend 82% of their time seated, this study delves into the musculoskeletal impact of prolonged sitting. Focusing on electromyographic (EMG) muscle activity in various positions, the research explores discomfort disparities between administrative workers and a control group, offering insights for challenges associated with extended sitting. Material and methods. Engaging 31 participants aged 30-40, the study investigates lateralization and discomfort in administrative workers versus a control group. Employing EMG and a Body Part Discomfort Assessment Checklist, the measurements adhere to ergonomic standards. Ethically approved, the study utilizes statistical analyses, uncovering the musculoskeletal effects of occupational postures. Results. EMG muscle activity in left and right upper limb extensors and flexors during diverse postures revealed no significant differences within or between administrative workers and the control group. Discomfort assessments displayed a non-significant trend, with the control group reporting slightly higher discomfort than administrative workers. Conclusions. The findings suggest short-term corrections minimally affect EMG activity, showcasing adaptability to adverse conditions. Administrative workers exhibit lower discomfort during uncorrected sitting, emphasizing adaptability. Although average EMG activity displays no significant difference, further investigations, including pressure algometry, are vital for nuanced insights into the relationship between EMG activity and subjective discomfort in ergonomic interventions.Technology Agency of the Czech Republic, TAC

The growth-adjusted CiteScores of Physics of Fluids

From Phan-Thien et al., “Growth-adjusted CiteScore,” Phys. Fluids 36(7), 070403 (2024), we learn that journal growth decreases CiteScore (all else being held equal). In this Editorial, we apply the teachings of Phan-Thien et al. to growth-adjust the CiteScore of the journal Physics of Fluids. We do so for the years for which the data are available, 2016-2023. We find that, over the course of its history, the growth of Physics of Fluids often suppressed its CiteScore

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

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

Copper and ZnO dual-catalyzed photo-assisted depolymerization of poly(methyl methacrylate) without deoxygenation

Despite significant advancements in thermal and photothermal depolymerizations, the success of these techniques relies on tedious deoxygenation procedures. Herein, we report the development of the depolymerization technique efficient without prior deoxygenation, which was enabled by copper/ligand complexes and the inclusion (0.25 wt% relative to solvent) of zinc oxide (ZnO) nanocrystals activated by UV light. This approach was tested for poly(methyl methacrylate) (PMMA) prepared by atom transfer radical polymerization (ATRP); the effects of solvent polarity and the activity of ligands were investigated. Unexpectedly, a low-activity Cu-complex with 2,2‘-bipyridine ligand, in combination with a low-polarity solvent, 1,2,4-trichlorobenzene, enabled relatively high depolymerization yields in less than 1 h at 150 °C. Higher activity ATRP complexes with tris(2-pyridylmethyl)amine (TPMA) and N,N,N‘,N‘‘,N‘‘-pentamethyldiethylenetriamine (PMDETA) ligands, were less efficient, which was associated with their thermal decomposition and/or the excessive formation of radicals and premature termination of the chain ends. The presented facile approach was designed to be used even in partially aerated reactors, opening new avenues for efficient depolymerization.NSF [DMR 2202747, DMR 2324168]; J. W. Fulbright Commission in the Czech Republic [2022-21-1]; Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2022/007, RP/CPS/2024-28/007]; Fonds de recherche du Quebec (FRQNT) [301734]; National Science Centre within the MINIATURA project [DEC-2023/07/X/ST5/01484]; Foundation for Polish Science (FNP)Carnegie Mellon University, CMU; Fundacja na rzecz Nauki Polskiej, FNP; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Fonds de recherche du Québec, FRQ; US-UK Fulbright Commission, (2022-21-1, RP/CPS/2024-28/007, RP/CPS/2022/007); Fonds de recherche du Québec – Nature et technologies, FRQNT, (301734); Narodowe Centrum Nauki, NCN, (DEC-2023/07/X/ST5/01484); National Science Foundation, NSF, (DMR 2202747, DMR 2324168

Flow-induced defects during metal injection molding: Role of powder morphology

Owing to the quality issues of highly filled compounds used in metal injection molding, the current research is focused on intercepting flow-induced inhomogeneities in multiphase compounds resulting from the segregation of metal powder particles from (typically) three/four-component polymer binders, resulting in an unacceptable porosity of the final sintered metal parts. A recently developed nondestructive approach for quantifying the extent of these flow-induced defects was employed to study the effect of the size and shape of water- and gas-atomized 17-4PH stainless steel powders on segregation. This method combines scanning electron microscopy/energy dispersive x-ray spectroscopy with an in-house analytical tool. The results show a higher tendency of coarser particles (D-50 of 20 mu m) for flow-induced defects, while an irregular shape (water-atomized particles) reduces this unwanted phenomenon.Ministerstvo Scaron;kolstv, Mldezcaron;e a Tecaron;lovchovy10.13039/501100001823 [RP/CPS/2024-28/005, RP/CPS/2024-28/003]; Ministry of Education, Youth and Sports of the Czech Republic-DKRV

The use of low-frequency current fluctuations in measuring the mobility of holes in the MEH-PPV polymer

A diagnostic method based on the evaluation of low-frequency current fluctuation spectra is presented. When measuring the current through a p-type MEH-PPV sample, the occurrence of fluctuation is observable which can be measured with an AC amplifier. A model has been proposed that proves that the fluctuations originate from the interaction between the valence band and the band gap traps. The mean value of the amplitudes of these fluctuations increases linearly with decreasing frequency with a slope from which the product of mobility and lifetime of current carriers µpτp = (9 ± 3) × 10−15 cm2V−1 was obtained. The hole lifetime of (0.27 ± 0.01) ns was evaluated from the luminescence relaxation using the time-correlated single photon counting (TCSPC) technique. The mobility value (3 ± 1) × 10−5 cm2 V−1s−1 calculated using the above methods was compared with the mobility 1.8 × 10−5 cm2 V−1s−1 determined by the CELIV method (Charge extraction by linearly increasing voltage) and good agreement was obtained.University Institute at Tomas Bata University in Zlin from the DKRVO funds; Centre of Polymer Systems from the DKRVO funds [RP/CPS/2024-28/007

Relation between residual tumor volume after surgery and overall survival in patients with glioblastoma - a single neuro-oncology center study

Aim: The aim of this study is to demonstrate the technical feasibility of volumetric assessment of residual tumor volume and to evaluate the eff ect of a precisely defi ned residual tumor volume on overall survival (OS) in patients with glioblastoma (GBM) . Materials and methods: Adult patients who underwent surgical resection for GBM in the University Hospital Olomouc from 2012 to 2016 were selected retrospectively. Patients attended regular clinical and MRI follow-up every three months. Early postoperative MRI scans were used in the study. In each patient, tumor segmentation was performed followed by creating a 3D model of tumor volume, which allowed the calculation of its volume both before and after surgery . Results: Results of 50 patients were available for a retrospective analysis. Our study showed a significant prolongation of OS only in the group with no contrastenhancing residue (median OS = 16.1 vs. 6.3 months) Patients with a combination of radical resection and oncological treatment with the Stupp protocol achieved further prolongation of OS with a mean of 19.6 months and a median of 14 months . Conclusion: Our paper describes the process of calculating the volume of the postoperative residual component of GBM using easily available software. According to the study findings, significantly better therapy results were achieved in patients with complete removal of the contrast -enhancing GBM component, supplemented by the most possible radical resection of the contrast non -enhancing components of the tumor