bluuebunny/crossref_metadata_2025 huggingface dataset:
Friction assessment of ultralow viscosity lubricant formulations based on a validated elastohydrodynamic simulation
Authors: Blanco-Rodríguez Javier , Porteiro Jacobo , López-Campos José A , Domínguez Beatriz , Cortada-Garcia Marti
Published: March 2023

High-performance engines are highly optimized machines; therefore, any identification of potential improvement requires a detailed study to assess different performance scenarios, working fluids and engine configurations. Simulation tools are among the best ways to study all possible options. In this framework, a validated elastohydrodynamic (EHD) simulation model of the connecting rod journal bearing is used to assess the performance of different lubricant formulations in mixed lubrication scenarios. To simulate a realistic scenario, a finite element analysis (FEA) is performed, where the assembly of connecting rod and shaft supports are modelled with finite element models (FEM) to account for elastic deformations on journal bearings. Furthermore, a set of oil properties is measured and collected to import into GT-Suite commercial software. This set enables us to consider the dependence of variables such as viscosity, density, specific heat transfer, and coefficient of friction on the shear rate, pressure, temperature, and air solution. Moreover, a friction assessment methodology is presented to choose the best lubricating oil for severe working conditions. This test method accounts for several factors: tribology, rheology, wear, and lubrication regime. The results are presented for three ultralow viscosity lubricants and the reference oil from validation. This assessment gives a complete comparison of lubricants performance, where lubrication regime and tribological losses are key factors to select the best candidate.
The Plane Hydrostatic Test as a Means for Selecting Appropriate Failure Criteria in Fibre Composites
Authors: Theocaris Pericles S.
Published: March 2023

Biaxial tests in anisotropic plates of composite materials do not provide a conclusive evidence for the selection of the appropriate version of the failure tensor polynomial criterion (FTP). On the other hand triaxial tests, which could be decisive, present difficulties and inaccuracies when anisotropic materials should be tested.

It was shown in this paper that a simple biaxial hydrostatic test in the transverse isotropic plane of a transversely isotropic material constitutes an accurate technique to decide which version of the criterion is valid. It was proved that the anisotropy along the strong stress axis of the material increases considerably the differences in failure in the transverse isotropic plane between the various criteria and it constitutes a safe test for deciding the validity of the appropriate criterion. Tests in biaxial hydrostatic tension or compression with different composite materials indicated clearly the superiority of the elliptic paraboloid failure surface criterion (EPFS).
Overview of Polymer Composites Using Recycled PET
Authors: Rebeiz K.S. , Fowler D.W. , Paul D.R.
Published: March 2023

Recycled poly(ethylene terephthalate), PET, mainly recovered from plastic beverage bottles, can be used to produce unsaturated polyester resins. Polymer concrete (PC) made with these resins has been investigated for potential use in construction and structural applications. Resins using recycled PET offer the possibility of a lower source cost of materials for making useful PC-based products. The recycling of PET in PC would also help solve some of the solid waste problem posed by plastics and save energy.
Chemical Exposure Tests on Perfluoroalkoxy Sheet
Authors: Van Tilburg V.S.M. , Stirling C.D. , Miller N.A.
Published: March 2023

Welded and unwelded panels of perfluoroalkoxy sheet have been exposed to 70% nitric acid, 98% sulphuric acid and 50% sodium hydroxide in such a manner that the panels were subjected to both total immersion and vapour phase conditions. Tensile and flexural test pieces were subjected to total immersion at the same time. Exposure periods were for three months at 40°C and for 28 days at 80°C. Deliberately strained specimens were totally immersed in 98% sulphuric acid and 50% sodium hydroxide for 28 days at 80°C.

After exposure, the panels were examined visually and under a scanning microscope (SEM) for any signs of chemical attack or cracking. The tensile and flexural test pieces were tested after exposure to determine whether there had been any adverse effects on properties.
Thermal and Viscoelastic Properties of Blends of Polypropylene with Thermotropic Liquid Crystalline Copolyesters
Authors: Yazaki Fumihiko , Tsubouchi Yasushi , Yosomiya Ryutoku
Published: March 2023

The thermal and viscoelastic properties of blends of polypropylene (PP) with thermotropic liquid crystalline copolyesters (LCP) have been investigated.

(1) Thermal characteristics, change of tan δ peaks, and SEM observation on the fracture surfaces of PP-LCP blends indicate behaviour characteristic of incompatible blend systems.

(2) Ternary blend systems containing chlorinated polypropylene (Cl-PP) showed increased interfacial interaction between the LCP and the matrix in comparison with the binary blend.

(3) Blends containing dimethylglyoxine (DMG) showed further improvement in interfacial interaction between the LCP and matrix. DMG is believed to act as a crosslinking agent.
Interpretation of Disorder and Fractal Dimensions in Transversely Loaded Unidirectional Composites
Authors: Pyrz Ryszard
Published: March 2023

The dispersion patterns of fibres in unidirectional composites are investigated by introducing second-order statistical functions which categorize the patterns of fibre centres as being aggregated, random or orderly. Furthermore these functions allow us to deduce the range of local disorder in the geometrical arrangement of fibres. A series of fracture surface profiles of transversely haded unidirectional composites are analysed in terms of fractal geometry. The fracture profiles are studied from three well-characterized materials having the same constituents but different dispersions of fibres. Fractal properties of fracture profiles are shown to correlate with an appropriate pattern's descriptors, which represent distance-based statistics of fibre distribution.
Fracture Characteristics of Discontinuous Carbon Fibre-Reinforced PPS and PES-C Composites
Authors: Zhang Mingqiu , Zeng Hanmin , Zhang Li , Lin Guangmin , Li Robert K.Y.
Published: March 2023

Tensile strength, σ b, Young's modulus, E, and critical stress intensity factor, K IC, of two types of short carbon fibre (CF) reinforced high performance brittle thermoplastics (CF/PPS and CF/PES-C) have been measured for different volume fraction, V f, of CF. Young's modulus increases linearly with increasing of V f with a Krenchel's efficiency factor of 0.05, whereas σ b and K 1C initially rise and then level up at V f of 25 vol. %. With the help of load-deflection curves and fractography, the experimental results have been analysed in the light of fibre-matrix adhesion characteristics. By using crack pinning model, the effective crack tensions, T, were calculated for both composites and they are 26 KJ/m (for CF/PPS) and 2.1 KJ/m (for CF/PES-C) respectively. The localized plastic deformation near fibre-matrix interface provides the major contribution to fracture toughness.
Marine Grade Polyester Resins for Boat Building in the 1990s
Authors: Norwood L.S. , Holton E.C.
Published: March 2023

Long-term evidence strongly supports the suitability of polyester resins for the construction of marine structures. However, misuse and incorrect selection has resulted in some distrust of their use for the manufacture of large structures.

In this paper the issues surrounding the limitations of general purpose resins are discussed and cost-effective alternatives suggested which, if used correctly, can resist blister formation indefinitely. The mechanical performance of these systems is also discussed and compared with vinyl esters, epoxies and toughened resins.

Under cold curing conditions isophthalic acid and isophthalic acid-neopentyl glycol based resins are more than adequate for resisting blister formation for, in some systems, in excess of 20 years at ambient temperatures and with laminate properties matching those of cold cured epoxy or vinyl ester systems.

Examples are given of the effective combination of different resin systems where the main structural laminate is protected by an environmental barrier providing cost-effective structural composites suitable for all marine structures.
Structure and Molecular Motions in Crosslinked Isotactic Polypropylene
Authors: de Candia F. , Michele A. , Renzulli A. , Vittoria V. , Chodak I.
Published: March 2023

The structure and the molecular motions of chemically crosslinked iPP samples have been analysed. The samples differ in gel content (i.e. degree of crosslinking). The X-ray analysis shows that two crystalline phases (α and γ) are present, their relative amount depending on the gel content. The thermal analysis suggests that the crosslinked samples are characterized by smaller and more defective crystals. The sample structure (in terms of crystallinity, phase composition and crystal defects) affects the molecular motion phenomena, analysed using the low resolution NMR spectroscopy. In particular, the analysis of the FID (free induction decay) signal shows a complex relationship between temperature, molecular mobility, and phase composition, which agrees with the thermal data.
Use of Fractional Factorial Design in the Development of a Method to Measure the Delamination of Unsaturated Polyester Resin Laminates
Authors: Skrifvars Mikael , Keinänen Kari , Blomqvist Tuula , Koivisto Vesa , Antell Siv , Skagerberg Bert
Published: March 2023

The development of a method for the measurement of delamination in unsaturated polyester resin laminates is described. A laminate is wedge-opened in a tensile testing machine, and the load at break is taken as a measurement for delamination. The results are compared with the delamination measured by the degree of fibre pull-out on the surface of laminates opened by hand. By testing a large sample series with both methods it could be shown by statistical analysis that wedge-opening in a tensile testing machine is more sensitive towards differences in laminate properties, and therefore gives more reliable results.
Amorphous Blends of Poly(Ethylene Terephthalate) and Poly(Butylene Terephthalate) through Ultraquenching
Authors: Avramova Nadka
Published: March 2023

Blends of poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) are obtained by means of an ultraquenching technique. The thermal behaviour, crystallization behaviour and mechanical properties are investigated by differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and mechanical testing. The results for as-quenched blends are compared with those for the same blends after three years of storage at -15°C. Both calorimetric and X-ray studies indicate that immediately after preparation, the blends are amorphous regardless of the composition. The stored blends are also amorphous. The thermal and mechanical properties of asquenched samples change significantly after a long time at low temperature relaxation. As-quenched blends exhibit two glass transition temperatures, while after the storage, at each composition, they are characterized by a single Tg intermediate between those of the pure components. It is demonstrated that ultraquenched PET/PBT blends are miscible in an amorphous state. Both components crystallize simultaneously at all compositions. Each component forms its own crystal phase and the presence of the other one does not disturb but enhances the crystallization process. A well expressed positive synergistic effect is observed in the mechanical properties of PET/PBT blends. Better performance of the ultraquenched PET/PBT blends is explained by their initial amorphous structure and amorphous miscibility.
Numerical Evaluation of the Influence of Loading Rate on the Interlaminar Fracture of Graphite/Epoxy
Authors: Chiu W.K. , Jones R.
Published: March 2023

The fracture toughness of materials that exhibit limited yielding at the crack tip is often characterised by evaluation of the “far-field” J integral. However, Carlsson et al(7) have shown that such “far-field” parameters may be less than ideal for composite materials where the crack tip in the matrix material undergoes extensive yielding. This paper investigates this proposition and presents the results of a numerical evaluation into the use of a near-tip energy integral, the so called T* parameter, for evaluating the fracture toughness of composite materials. Here attention is focused on both the near-tip fracture parameter and on load history effects.
The Control of Pore Size in Polypropylene/Paraffin Mixtures Using Intercalated Guest SiO2 Particles
Authors: Sakami Hiroshi
Published: March 2023

This paper discusses the control of fine layer-like pores in high crystallinity polypropylene (PP) films from a mixture of liquid paraffin and silica particles (SiO2) by rolled compression. Mixtures with various ratios were hot rolled, and then paraffin was extracted in organic solvents. The fine structure of these films was investigated by measuring the apparent specific volume, the surface area using the after nitrogen gas adsorption-desorption method, and small angle X-ray scattering (SAXS). Polythene films with mixing ratios with paraffin from 0.10 to 0.50 w/w showed layer-like pores using rolling ratios of 10 to 30 at 115°C. A wide surface area of 160 m2/g was achieved by rolling the films with mixing ratios 0.17 to 0.10 at rolling ratios of 20 to 30. The SiO2 guest was randomly dispersed in paraffin. It was suggested that a regularly spaced structure of polypropylene layers (host) and layer-like pores of 9 nm and 10.5 nm thick, respectively, is formed at rolling ratios of 25 to 30. The SiO2 plays an important role of intercalation through the polypropylene thin layers, oriented by rolled compression.
Structure and Molecular Weight Determinations of Unsaturated Polyester Prepolymers by Steric Exclusion Chromatography
Authors: Leroux F. , Mortaigne B. , Belan F.
Published: March 2023

Four model unsaturated polyester prepolymers and two industrial resins were studied by size exclusion chromatography (SEC).

A calibration curve was set up with model resins and used to characterize the industrial unsaturated polyester resins. Weight average molecular prepolymer weights were determined from the new calibration curve. They were lower than those determined with polystyrene or epoxy calibration curves.

The observation of SEC chromatographs proves the formation of diol-ISO-diol (where ISO = isophthalic acid) and MAA-diol-MAA structures (where MAA = maleic anhydride) in the beginning of polycondensation reactions. This gives information on the future structure of the UP network.
Effects of Interleaving on the Impact and Impact Fatigue Responses of Cross-ply Carbon Fibre/Epoxy Laminates
Authors: Yuan Q. , Karger-Kocsis J.
Published: March 2023

The impact performance of carbon fibre/epoxy (CF/EP) laminates with and without interleaving was investigated by an instrumented falling weight impact (IFWI) method both in the perforation and the subperforation ranges. Tests in the subperforation range were performed either by single impacts with various energy levels or by multiple impacts (impact fatigue) at the same incident energy (Ein). In the former case both the maximum load (Fmax) and the maximum deflection (xmax) increased with increasing Ein. Under impact fatigue conditions the absorbed energy (Ea) and xmax increased, whereas Fmax decreased with increasing numbers of impacts (NOI). It was recommended to relate the stiffness deterioration of the plates to the change in the initial or secant slope of the rebound fractograms represented as F-x traces. The effects of position, number and thickness of the adhesive interlayers (A) incorporated were also studied. Positioning the interleaf in the neutral axis (mid-plane) of the composite plates does not enhance the resistance to delamination are low energy levels. In contrast, interleaving in the compression and/or tension sides of the plates depressed delamination, detected by ultrasonic C-scanning, considerably. The cone of damage across the thickness became narrower due to interleaving, as revealed by microscopic and ultrasonic B-scanning techniques.
A Small Angle X-Ray Scattering Study of Melt Separation in Crosslinked Low Density Polyethylene
Authors: Lee Y.D. , Phillips P.J. , Lin J.S.
Published: March 2023

Studies of the sol-gel separation process, believed to occur in chemically crosslinked low density polyethylene at temperatures just above the melting point, have been carried out using small angle x-ray scattering. Analyses of the results demonstrate that two phases do indeed exist after the lamellae disappear. Scattering that occurs is symptomatic of isolated scattering entities. Comparison with theoretically predicted scattering envelopes show that the sol exists as small droplets which are disc-like at a temperature immediately above the melting point, but that they become spherical as temperature is increased, ultimately disappearing when miscibility returns.
Properties of Fibres Spun from Blends of a Thermotropic Liquid Crystalline Block Copolymer with Poly(ethylene terephthalate)
Authors: Giesa Reiner , Joslin Scott , Melot Denis , Farris Richard J.
Published: March 2023

Triad4-co-PBT, a thermotropic liquid crystalline (TLCP) block copolyester has been blended with fibre grade poly(thylene terephthalate) (PET) to investigate the potential of in-situ fibre reinforcement. Fibres containing 5 to 80 wt.% TLCP were extruded and the effects of processing conditions were studied, e.g. spinning temperature and post treatment conditions. The fibres were evaluated for mechanical performance, dimensional stability (shrinkage) and development of shrinkage stresses. The optimal processing temperature for these blends was determined to be between 270 - 275°C based on mechanical performance and their fibre WAXS diffraction patterns. The optimal blend composition was found to be 10 wt.%. The highest modulus (19.8 GPa) was achieved with a 20 wt.% blend, but this system had a low ultimate strength (725 MPa) and numerous defects in the cold drawn fibre. A study of the post treatment process revealed that fibres drawn at 220°C exhibited increased thermal stability independent of TLCP content compared to those drawn at lower drawing temperature. Scanning electron microscopy of fractured fibre cross sections revealed a two phase morphology with the LCP phase dispersed as fine spherical particles
Shrinkage Control in Fibre Reinforced Polymers III: Carbon Fibre Reinforced Polyesters with Expanding Monomers and Low Profile Additives
Authors: Piggott M.R. , Zhou W. (Vincent)
Published: March 2023

Copolymers of polyester were made with two spiro orthocarbonates: cyclohexane and cyclohexene. They were also used to make unidirectional carbon fibre composites, and the properties of polymers and composites were compared with those made with a low profile additive (a copolymer of methyl and allyl methacrylates). The copolymers were not effective in reducing the shrinkage stress of the resin, except through a reduction in glass transition temperature. They gave composites with poor properties. The low profile additive was effective in reducing the shrinkage volume, but at the cost of a reduction in tensile strength. It did not affect the shrinkage stress very much, and did not have much effect on composite properties. Thus, while it is advantageous to use low profile additives with reinforced polyesters, it is not beneficial to use spiro orthocarbonate expanding monomers. Overall, the three papers in this series strongly suggest that, while controlling shrinkage stress may well be useful, it cannot be realized to any useful extent by using expanding monomers.
NDT of Composite Materials - Problems and Solutions 2. Relaxation Spectrometry for the Structural Study of Polymers and Polymer Composites
Authors: Matiss I.
Published: March 2023

The use of mechanical and dielectric spectrometry for macrostructural studies (cure, ageing, moisture absorption, etc.) of polymers and composite materials is described. Dynamic relaxation parameters including the most probable relaxation time, and the width and symmetry of the spectrum are proposed for the quantitative evaluation of the structure. The analogy between mechanical and dielectric relaxation phenomena is discussed.
Molecular Transport of Organic Esters into Copolymeric and Terpolymeric Membranes
Authors: Aminabhavi Tejraj M. , Harlapur Sujata F. , Ortego J. Dale
Published: March 2023

Solvent uptake into thin fluoropolymer membranes (FC-2179 and FLS-2650) has been measured as a function of temperature using a sorption gravimetric method. Diffusion coefficients, percent mass uptake, and apparent activation energies for the process of diffusion and permeation have been obtained. Both polymers exhibit anomalous diffusion behaviour and this is due to specific interactions between polymer chain segments and esters. Molecular migration of esters into the dense membrane materials showed a dependence on polymer morphology and/or their chemical structures. The liquid concentration profiles have been calculated at different depths of the membranes for different time intervals. A numerical mediod based on a finite difference approach was also employed to predict concentration profiles of liquids into the membrane materials.
On Microcracking in Composite Laminates under Thermal and Mechanical Loading
Authors: McManus Hugh L. , Maddocks Jason R.
Published: March 2023

Composite laminates used in many applications are exposed to both thermal and mechanical loads. These loads can cause cracks in the matrix, changing the laminates’ properties. An analytical methodology is developed to predict microcrack density in a general laminate exposed to an arbitrary thermomechanical load history. The analysis uses a shear lag stress solution in conjunction with an energy-based cracking criterion. It is found that crack densities depend on the stress in the cracking ply group, regardless of the source of the stress. Crack densities are a nonlinear function of stress, however, so if both thermal and mechanical loads are present, the cracking response is coupled. Experimental investigation is used to verify the analysis. Correlation between analysis and experiment is generally excellent. The method successfully predicts the initiation of cracking and crack accumulation under both thermal and mechanical loads, in most ply groups in a variety of laminates, using a single set of ply material properties. The cases where the analysis and experiment do not agree shed some light on the limits of current modelling techniques. Given an understanding of these limits, the analysis appears to be a useful preliminary design tool.
Structure-Performance Analysis of Two-Dimensional Woven Fabric Composites
Authors: Vandeurzen Philippe , Ivens Jan , Verpoest Ignaas
Published: March 2023

A revival of interest in woven fabric composites has been observed in recent years. However, our understanding of their elastic and strength behaviour is still in its infancy. Modelling starts with the creation of a three-dimensional geometric model of the fabric structure. This analysis results in a logical and automated partition of the unit cell into a number of micro-cells, and the prediction of local fibre volume fractions and yarn orientations. Through the application of a modified Fabric Geometry Model, the full set of elastic constants for the orthotropic material unit cell is obtained. A parametric study was performed to understand how the different geometric parameters of the fabric can be combined to determine the elastic behaviour of the composite material.
Effects of Structure and Microcracks on the Flexure, Interlaminar Shear and Impact Properties of Three-Dimensional Composites
Authors: Chou Shen , Chen Hong-En
Published: March 2023

Three-dimensional carbon fibre/epoxy resin composites were prepared, which had either three-axis or five-axis carbon fabrics (3D-3A or 3D-5A) in four woven gauges, and Teflon® was embedded in the fabric structures to initiate various types of microcracks. The flexural, interlaminar shear, and impact properties of these 3-D composites were studied. The results indicated that the flexural properties of 3D-3A were better than those of 3D-5A.

However, 3D-5A structures gave better impact strength compared to 3D-3A. The interlaminar shear strength depended on the weave gauge. The effect of microcracks on the properties of 3-D composites was generally kept within 10%, but transverse microcracks lowered the flexural properties of 3-D composites by 10–20%. The 3D-3A composites showed cracks along the interface between the Z axial bundles and the matrix, whereas the 3D-5A showed 45°-axial bundle pull-out.
Processes of Contaminant Transfer into Foods by Diffusion-Convection or by Diffusion from Packaging Made of a Recycled Layer and a Functional Barrier
Authors: Laoubi A. , Vergnaud J.M.
Published: March 2023

Reusing old plastics as food packaging necessitates the presence of a functional barrier (made of a virgin polymer) between the food and old plastics. The transfer of the potent contaminant through the packaging is controlled by diffusion, leaving aside of the transfer of the food into the packaging. Depending on whether the food is liquid or solid, the process of transfer of the contaminant in the food is controlled either by convection, with a coefficient of convective transfer in the food, or by diffusion. The two processes have been studied in detail and the results are expressed in terms of master curves. Some emphasis is put on the effect of the value of the diffusivity in the food and of the coefficient of mass transfer on the contaminant transfer into the food.
Impregnation Techniques for Thermoplastic Matrix Composites
Authors: Miller A. , Gibson A.G.
Published: March 2023

This paper reviews the techniques available for the impregnation of reinforcing fibres with thermoplastic resins. The key material factors influencing the achievement of impregnation are outlined and the current impregnation technologies are discussed. The techniques are divided into two categories: those that aim to reduce the viscosity in order to achieve rapid impregnation, the pre-impregnation processes, and the processes that attempt to reduce the distance that the resin is required to flow, which involve intimate mixing of constituents prior to melting, the mingling processes. The techniques used to mingle fine polymer powder and continuous fibres are examined and the various elements of a powder impregnation line are reviewed. Applications of powder impregnated composites are also discussed.
Continuous Manufacturing of Thermoplastic Composite Sheets
Authors: Ostgathe M. , Mayer C. , Neitzel M.
Published: March 2023

For high speed press forming of fibre reinforced thermoplastic sheet materials, a high impregnation quality is advantageous for utilisation of the potential regarding mechanical properties. Hence, the impregnation process is crucial to material properties and economy. In this paper the influence of process parameters on mechanical properties is investigated using an isobaric double belt press technique. Relevant process parameters are defined and varied using the Taguchi technique.

Evaluating impregnation quality with 3-point bending tests and micrographs, the influence and meaning of process parameters is specified. Process parameters are optimised regarding flexural stress and strength, and a process window for a fabric reinforced polyamide PA 12 is defined.
The take-off of Drosophila research in 1930–1950s Edinburgh
Authors: Beaven Robin
Published: March 2023

The fruit fly, Drosophila melanogaster, is a simple and powerful model organism. It has played a critical role over more than a century, for example in establishing the field of genetics, and in foundational insights into the molecular basis of development. From the 1930s until today, researchers at the University of Edinburgh have used Drosophila to tackle questions in basic and biomedical science. Here the history of the initial decades of this research is explored, beginning with the introduction of Drosophila research to Edinburgh by Francis Albert Eley Crew, in the newly established Institute of Animal Genetics. This period of research includes the discovery that chemicals can cause genetic mutation. This was demonstrated by research of the effects of mustard gas on flies by Charlotte Auerbach and colleagues, guided by the future Nobel laureate Hermann Muller. Drosophila research was also formative in Conrad Hal Waddington’s conceptual thinking about developmental biology, including in his vision of the epigenetic landscape. This holistic, systems-level view of the control of development was far before its time and has continued to be influential to this day in our conceptualisation of developmental biology and in the increasingly important field of systems biology. Waddington’s experiments with Drosophila in Edinburgh also gave rise to the evolutionary concept of genetic assimilation, in which an environmentally induced phenotype subsequently becomes genetically encoded.
Fractional Epidermal Skin Grafts in Hard-to-Heal Wounds: Case Series
Authors: Janowska Agata , Fidanzi Cristian , Romanelli Marco , Iannone Michela , Oranges Teresa , Montaquila Francesca , Dini Valentina
Published: March 2023

Cellutome™ is a minimally invasive, automated system for harvesting fractional epidermal micrografts. This therapy is indicated for granulating, small size, poor exuding acute wounds. We enrolled 15 patients with 9 venous leg ulcers and 6 atypical ulcers. The micrografts were applied with a nonadherent dressing and covered with a polyurethane foam and multilayer bandage. We scheduled 3 weekly visits for the change of the secondary dressings and multilayer bandage and clinical assessment (Wound Bed Score [WBS], pain assessment, and healing rate). The lesions were measured with the Silhouette Star™ system, a software that allows measurement of perimeter and area from a digital image. The only symptom during the procedure was a sensation of warmth. The donor area healed in 2 weeks in all patients ( n = 15). We reported an area reduction of 24.30% in typical ulcers and 38.82% in atypical ulcers after 3 weeks. The average WBS improved in all ulcers from 13.06 to 14.93. The average healing rate was 0.19 mm/day both in typical and atypical ulcers. Consequently, in our small case series fractionated epidermal graft treatment significantly promoted the healing rate in all chronic ulcers regardless of etiology. Future studies with larger case series will be needed.
Continuous-flow Heck coupling reactions catalyzed by Pd complexes of amidoxime fibers
Authors: Xie Jiaxin , Lu Siyu , Zhang Yilin , Lu Xiaohan , Ding Zhen , Tao Tingxian , Xu Maodong , Wu Zhichuan
Published: March 2023

Improving production efficiency and developing green catalytic systems are key issues for applying Heck coupling reactions in the chemical industry. In this study, an amidoxime-fiber-supported Pd catalyst is prepared from polyacrylonitrile fiber, hydroxylamine hydrochloride, and PdCl2. The morphology and structure of amidoxime-fiber-supported Pd are characterized by scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectrometer, X-ray diffraction, and inductively coupled plasma-optical emission spectrometer. A packed-bed flow reactor is designed and employed for catalysis of the Heck reaction of iodobenzene and styrene based on the amidoxime-fiber-supported Pd catalyst. The effects of reaction temperature, flow rate, cycle time, and reactant concentration on the conversion and yield are investigated. The results show that the optimal conditions for the continuous-flow single reactor are 70 °C, iodobenzene concentration of 30 mmol L−1 in a solution of N,N-dimethylformamide (100 mL) under continuous flow at a flow rate of 2 mL min−1. The catalyst showed good activity and stability after a continuous operation time of 50 h, with catalytic activity 2.21 times higher than that obtained with traditional batch reaction. Furthermore, we have established a new flow reaction system based on the numbering-up of reactors with a parallel connection. The catalytic efficiency of four parallel reactors is four times higher than that of a single reactor. Kinetic studies reveal that the reaction has low activation energy (8.8771 kJ mol−1), indicating that amidoxime-fiber-supported Pd has good catalytic activity. This research provides an alternative pathway for highly efficient Heck coupling in continuous flow.
1984 revisited: Implications for leaders in higher education in the United States
Authors: Evans Charles Samuel , Kirk-Jenkins Andrea J , Lader Bowen
Published: March 2023

This article offers a current perspective on George Orwell’s 1984 (1949) utopian society in the context of 2022 and implications for higher education and society in the United States. Societies have experienced numerous issues portrayed in 1984 including power struggles and censorship, and identity politics and cancel culture are impeding an open discussion of ideas. Higher education has been considered a bastion of intellectual inquiry and spirited discussions, where faculty members are in a position of authority in the classroom. This authority can influence the learning environment and experiences; however, both faculty and students are feeling threats from various sectors both internally and externally. To address these matters, findings from various reports and studies indicate a need for greater diversity in perspectives on critical issues in academia, which could impact the preparation and the nature of learning experiences provided for students.
Cell shape characteristics of human skeletal muscle cells as a predictor of myogenic competency: A new paradigm towards precision cell therapy
Authors: Desprez Charlotte , Danovi Davide , Knowles Charles H , Day Richard M
Published: March 2023

Skeletal muscle-derived cells (SMDC) hold tremendous potential for replenishing dysfunctional muscle lost due to disease or trauma. Current therapeutic usage of SMDC relies on harvesting autologous cells from muscle biopsies that are subsequently expanded in vitro before re-implantation into the patient. Heterogeneity can arise from multiple factors including quality of the starting biopsy, age and comorbidity affecting the processed SMDC. Quality attributes intended for clinical use often focus on minimum levels of myogenic cell marker expression. Such approaches do not evaluate the likelihood of SMDC to differentiate and form myofibres when implanted in vivo, which ultimately determines the likelihood of muscle regeneration. Predicting the therapeutic potency of SMDC in vitro prior to implantation is key to developing successful therapeutics in regenerative medicine and reducing implementation costs. Here, we report on the development of a novel SMDC profiling tool to examine populations of cells in vitro derived from different donors. We developed an image-based pipeline to quantify morphological features and extracted cell shape descriptors. We investigated whether these could predict heterogeneity in the formation of myotubes and correlate with the myogenic fusion index. Several of the early cell shape characteristics were found to negatively correlate with the fusion index. These included total area occupied by cells, area shape, bounding box area, compactness, equivalent diameter, minimum ferret diameter, minor axis length and perimeter of SMDC at 24 h after initiating culture. The information extracted with our approach indicates live cell imaging can detect a range of cell phenotypes based on cell-shape alone and preserving cell integrity could be used to predict propensity to form myotubes in vitro and functional tissue in vivo.
Abundance and absence: Human-microbial co-evolution in the Anthropocene
Authors: Bradshaw Aaron
Published: March 2023

Human-microbe relations have undergone a profound shift over the past 100 years. The discovery of antibiotics, increasing levels of pollution, and urban and agricultural intensification have led to the proliferation and diversification of novel resistance genes and microorganisms. This abundance has unfolded against a backdrop of microbial absence that is the other side of the antimicrobial coin; reductions in the quantity and diversity of human-microbe interactions are now registering as epidemics of chronic non-communicable diseases in urban populations. Building from this paradoxical situation of ‘abundance’ and ‘absence’, this article reviews the molecular-genetic, macroscale-infrastructural, and community-ecological aspects of microbial evolution at a time when human actions are a critical force in shaping their directions.
Negotiating Emerging Adulthood at the Onset of COVID-19 in Singapore
Authors: Yeo GeckHong , Yang Chia-chen
Published: March 2023

Historical events and cultural contexts have major implications for emerging adults’ developmental experiences. Underpinned by the theory of emerging adulthood, this study examined how COVID-19 interacted with Singapore youths’ negotiation of emerging adulthood. We employed a mixed-methods design and drew on Telegram text messaging among 757 Singapore youths ( Mage = 19.60, SD = .63) at the onset of the pandemic. Using qualitative analysis, we examined whether the five features of emerging adulthood were salient in the context of the pandemic among Singapore youths. Using the quantitative methodology of topic modelling, we identified five culturally salient domains that emerged in Singapore youths’ negotiation of the developmental features of emerging adulthood at the onset of the COVID-19 pandemic, with work and studies being the most salient domain. Finally, quantitative analysis using a person-centered approach revealed four classes of youths with varying patterns of how experiences of the COVID-19 pandemic interacted with their negotiation of developmental features and domains of emerging adulthood: the Struggling youths, Relationship-Oriented youths, Me generation, and Go-Getters. Results from this study revealed how the pandemic and socio-cultural conditions of the Singapore society presented a unique developmental context for emerging adults. Practical implications for supporting each group of emerging adults are discussed.
What factors contribute towards ambulance on-scene times for suspected stroke patients? An observational study
Authors: McClelland Graham , Burrow Emma , Alton Abi , Shaw Lisa , Finch Tracy , Price Chris
Published: March 2023

Introduction:

Pre-hospital stroke care focusses on rapid access to specialist stroke units, but UK ambulance data shows increasing pre-hospital times. This study aimed to describe factors contributing towards ambulance on-scene times (OST) for suspected stroke patients and identify targets for a future intervention.

Patients and methods:

Ambulance clinicians in North East Ambulance Service were asked to complete a survey after transporting any suspected stroke patients to describe the patient encounter, interventions and timings. Completed surveys were linked with electronic patient care records. Potentially modifiable factors were identified by the study team. Poisson regression analysis quantified the association of selected potentially modifiable factors with OST.

Results:

About 2037 suspected stroke patients were conveyed between July and December 2021, resulting in 581 fully completed surveys by 359 different clinicians. The median age of patients was 75 years (interquartile range (IQR) 66–83) and 52% of patients were male. Median OST was 33 min (IQR 26–41). Three potentially modifiable factors were identified as contributors to extended OST. Performing additional advanced neurological assessments added 10% to OST (34 vs 31 min, p = 0.008); intravenous cannulation added 13% (35 vs 31 min, p = <0.001) and ECGs added 22% (35 vs 28 min, p = <0.001).

Conclusions:

This study identified three potentially modifiable factors that increased pre-hospital OST with suspected stroke patients. This type of data can be used to target interventions at behaviours that extend pre-hospital OST but which have questionable patient benefit. This approach will be evaluated in a follow up study in the North East of England.
The Power of Music: But What Kind?
Authors: Liu Chiao-Wei
Published: March 2023

One of the enchanting powers of music is its ability to transcend language and culture and capture complex human experiences. But music, rather than a mere reflection of social reality, also constitutes within discursive practices and contributes to the social construction of gender and sexuality. By looking at two different examples of music works, I call attention to the social-political role music plays in our life. I argue that attending to the sociopolitical perspective of music is to understand how music traverses across lives (and materials) and creates different relationships with and among us. This is an attempt to better comprehend human experiences, through which, we may repair and recreate new relationships. I end this column with a few curriculum ideas.
The impact of anti-eosinophilic therapy on exercise capacity and inspiratory muscle strength in patients with severe asthma
Authors: Franceschi Elisa , Drick Nora , Fuge Jan , Santus Pierachille , Fischer Bettina , Kayser Moritz , Welte Tobias , Suhling Hendrik
Published: March 2023

Introduction

Exercise limitation is frequently described among asthmatic patients and could be related to different mechanisms of the pulmonary, cardiovascular and muscular systems. Despite this, cardiopulmonary exercise testing (CPET) does not have an established role in the management of severe asthma. The aim of our study was to investigate the role of CPET and inspiratory pressure measurement in exercise capacity and muscle strength in severe asthmatic patients treated with anti-IL-5 therapy.

Methods

A monocentric observational study was conducted at Hanover Medical School, Germany, from April 2018 to June 2019. Patients affected by severe asthma treated with either mepolizumab or benralizumab were included. All patients underwent CPET before the initiation of antibody therapy and after 3 months, and follow-up visits were scheduled at 3, 6 and 12 months with plethysmography, inspiratory pressure measurement and blood gas analysis.

Results

14 patients were enrolled: 10 (71.4%) females, median age 52 years (IQR 47–61). Seven patients were treated with benralizumab, seven with mepolizumab. Oxygen uptake (V′O2peak) did not change significantly after 3 months of antibody treatment, while the mean value of the breathing reserve exhaustion reduced significantly from 78% to 60% (p=0.004). Whereas at baseline seven patients depleted the breathing reserve and two of them experienced oxygen desaturation during exercise, at 3 months no one presented any desaturation or breathing reserve exhaustion. The inspiratory pressure remained unchanged before and after the antibody therapy.

Conclusion

CPET could show hints of alveolar recruitment and ventilatory efficiency in severe asthma patients treated with antibody therapy.
Airspace Dimension Assessment for early detection of lung function impairment in the peripheral airways of firefighters
Authors: Kisiel Marta A. , Cai Gui-Hong , Petersson Sjögren Madeleine , Löndahl Jakob , Jakobsson Jonas , Wollmer Per , Malinovschi Andrei , Svartengren Magnus
Published: March 2023

Introduction

Firefighters have increased risk of chronic respiratory disease. Standard clinical techniques used in medical checkups may not detect the earliest microstructural changes in peripheral airways. A new technique called Airspace Dimension Assessment (AiDA) has been shown to enable early detection of emphysema in COPD. This method may be useful in the occupational setting to detect early pulmonary changes and enable prevention. The aim of the present study was to evaluate whether AiDA detects changes in the most peripheral airways of firefighters.

Methods

AiDA, measuring the effective airspace radius (rAiDA) and zero-second recovery (R0), was used as a complement to other standardised lung function measures in 21 male firefighters and 16 age-matched male controls.

Results

There were significant differences inrAiDAandR0between firefighters (mean±sdrAiDA0.301±0.024 mm; mean±sdR00.336±0.116 arbitrary units) and controls (mean±sdrAiDA0.276±0.044 mm; mean±sdR00.5760.168 arbitrary units), p=0.03 and p<0.001, respectively. Higher forced vital capacity was found in firefighters (mean 101% of predicted) than in controls (mean 93% of predicted; p=0.03). No significant differences were found with regard to either the ratio between forced expiratory volume in 1 s and forced vital capacity or forced expiratory volume in 1 s. The majority of firefighters had diffusing capacity of the lung for carbon monoxide, oscillometry and single-breath nitrogen washout values within the normal ranges.

Conclusion

AiDA parameters can provide information on early pulmonary peripheral changes that may not be seen with standard techniques used in screening of pulmonary function.
Decreased breathing variability is associated with poorer outcome in mechanically ventilated patients
Authors: Rolland-Debord Camille , Poitou Tymothee , Bureau Come , Rivals Isabelle , Similowski Thomas , Demoule Alexandre
Published: March 2023

Rationale

Breathing is a cyclic activity that is variable by nature. Breathing variability is modified in mechanically ventilated patients. We aimed to evaluate whether decreased variability on the day of transition from assist-control ventilation to a partial mode of assistance was associated with a poorer outcome.

Methods

This was an ancillary study of a multicentre, randomised, controlled trial comparing neurally adjusted ventilatory assist to pressure support ventilation. Flow and the electrical activity of the diaphragm (EAdi) were recorded within 48 h of switching from controlled ventilation to a partial mode of ventilatory assistance. Variability of flow and EAdi-related variables were quantified by the coefficient of variation, the amplitude ratio of the spectrum's first harmonic to its zero-frequency component (H1/DC) and two surrogates of complexity.

Main results

98 patients ventilated for a median duration of 5 days were included. H1/DC of inspiratory flow and EAdi were lower in survivors than in nonsurvivors, suggesting a higher breathing variability in this population (for flow, 37%versus45%, p=0.041; for EAdi, 42%versus52%, p=0.002). By multivariate analysis, H1/DC of inspiratory EAdi was independently associated with day-28 mortality (OR 1.10, p=0.002). H1/DC of inspiratory EAdi was lower in patients with a duration of mechanical ventilation <8 days (41%versus45%, p=0.022). Noise limit and the largest Lyapunov exponent suggested a lower complexity in patients with a duration of mechanical ventilation <8 days.

Conclusion

Higher breathing variability and lower complexity are associated with higher survival and lower duration of mechanical ventilation.