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Mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene(PTFE)

Friction 2024年第5期12卷 997-1015页

作者： Pontus JOHANSSON P.MARKLUND M.BJORLING Y.SHI division of Machine Element LuleåUniversity of TechnologyLuleåSE-97187Sweden

Carbon fiber reinforced polytetrafluoroethylene (CF/PTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. Moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/PTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/PTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/PTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. Moreover, a loosely adhered tribofilm was observed on top of the CF/PTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm could be an indication of moisture-driven lubricatio

关键词： polymer composite tribofilm tribochemistry atmosphere

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New approach for particle size and shape analysis of iron-based oxygen carriers at multiple oxidation states

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Particuology 2024年第7期90卷 493-503页

作者： Victor Purnomo Marcelo Dal Belo Takehara Robin Faust Lidiya Abdisa Ejjeta Henrik Leion division of Energy and Materials Department of Chemistry and Chemical EngineeringChalmers University of TechnologyGöteborg 41258Sweden division of Energy Science Department of Engineering Sciences and MathematicsLuleåUniversity of TechnologyLuleå97187Sweden

One of the crucial issues in the chemical looping technology lies in its bed material:the oxygen carrier.Particle size analysis of an oxygen carrier is important since in a fluidized bed the material can only work well within a specific size range.While the favorable size ranges for oxygen carrier materials have already been reported,none of the published studies has analyzed the particle size and shape of oxygen carriers in detail.Furthermore,the effect of oxygen carriers'oxidation degree on such properties has not been considered either.This study aimed to report the particle size and shape analysis of five iron-based oxygen carriers,one natural ore,one synthetic material,and three residue products,at different oxidation degrees using dynamic image analysis(DIA).The oxygen carriers were prepared at different mass conversion degrees in a fluidized bed batch reactor.The size distribution,sphericity,and aspect ratio of the oxygen carrier particles were examined experimentally using a Camsizer instrument.Our results show that the DIA method was successfully able to analyze the particle size and shape of our oxygen carriers with satisfying accuracy for comparison.The oxidation state of the investigated materials seems to only affect the particle size and shape of oxygen carriers to a minor extent.However,exposures to redox cycles in a fluidized bed reactor may alter the particle size and shape of most oxygen carriers.

关键词： Oxygen carrier Size and shape analysis Dynamic image analysis Oxidation state Fluidized bed Chemical looping

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Reconstitution of double-negative T cells after cord blood transplantation and its predictive value for acute graft-versus-host disease

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中华医学杂志(英文版) 2024年第10期137卷 1207-1217页

作者： Pan Tianzhong Ding Peng Huang Aijie Tang Baolin Song Kaidi Sun Guangyu Wu Yue Yang Shiying Chen Xingchi Wang Dongyao Zhu Xiaoyu Department of Hematology The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China Anhui Provincial Key Laboratory of Blood Research and Applications Hefei Anhui China Blood and Cell Therapy Institute Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China The First Affiliated Hospital of USTC Division of Life Sciences and Medicine University of Science and Technology of China Hefei Anhui China

Background: With an increasing number of patients with hematological malignancies being treated with umbilical cord blood transplantation (UCBT), the correlation between immune reconstitution (IR) after UCBT and graft-versus-host disease (GVHD) has been reported successively, but reports on double-negative T (DNT) cell reconstitution and its association with acute GVHD (aGVHD) after UCBT are lacking.Methods: A population-based observational study was conducted among 131 patients with hematological malignancies who underwent single-unit UCBT as their first transplant at the Department of Hematology, the First Affiliated Hospital of USTC, between August 2018 and June 2021. IR differences were compared between the patients with and without aGVHD.Results: The absolute number of DNT cells in the healthy Chinese population was 109 (70-157)/μL, accounting for 5.82 (3.98-8.19)% of lymphocytes. DNT cells showed delayed recovery and could not reach their normal levels even one year after transplantation. Importantly, the absolute number and percentage of DNT cells were significantly higher in UCBT patients without aGVHD than in those with aGVHD within one year (F = 4.684,P = 0.039 andF = 5.583,P = 0.026, respectively). In addition, the number of DNT cells in the first month after transplantation decreased significantly with the degree of aGVHD increased, and faster DNT cell reconstitution in the first month after UCBT was an independent protective factor for aGVHD (HR = 0.46, 95% confidence interval [CI]: 0.23-0.93;P = 0.031).Conclusions: Compared to the number of DNT cells in Chinese healthy people, the reconstitution of DNT cells in adults with hematological malignancies after UCBT was slow. In addition, the faster reconstitution of DNT cells in the early stage after transplantation was associated with a lower incidence of aGVHD.

关键词： Umbilical cord blood transplantation Graft-versus-host disease Immune reconstitution Double negative T Hematological Malignancies Treg cell Breg cell

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Modified DS np Chart Using Generalized Multiple Dependent State Sampling under Time Truncated Life Test

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2471-2495页

作者： Wimonmas Bamrungsetthapong Pramote Charongrattanasakul division of Applied Statistics Department of Mathematics and Computer ScienceFaculty of Science and TechnologyRajamangala University of Technology ThanyaburiPathum Thani12110Thailand division of Mathematics Department of Mathematics and Computer ScienceFaculty of Science and TechnologyRajamangala University of Technology KrungthepBangkok10120Thailand

This study presents the design of a modified attributed control chart based on a double sampling(DS)np chart applied in combination with generalized multiple dependent state(GMDS)sampling to monitor the mean life of the product based on the time truncated life test employing theWeibull distribution.The control chart developed supports the examination of the mean lifespan variation for a particular product in the process of manufacturing.Three control limit levels are used:the warning control limit,inner control limit,and outer control limit.Together,they enhance the capability for variation detection.A genetic algorithm can be used for optimization during the in-control process,whereby the optimal parameters can be established for the proposed control chart.The control chart performance is assessed using the average run length,while the influence of the model parameters upon the control chart solution is assessed via sensitivity analysis based on an orthogonal experimental design withmultiple linear regression.A comparative study was conducted based on the out-of-control average run length,in which the developed control chart offered greater sensitivity in the detection of process shifts while making use of smaller samples on average than is the case for existing control charts.Finally,to exhibit the utility of the developed control chart,this paper presents its application using simulated data with parameters drawn from the real set of data.

关键词： Modified DS np chart generalizedmultiple dependent state sampling time truncated life test Weibull distribution average run length average sample size

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c-myb is involved in CML progression and is a therapeutic target in the zebrafish CML model

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Animal Models and Experimental Medicine 2024年第2期7卷 136-144页

作者： Yin Ye Xiaojun Yang Feifei Li Wei Liu Wenqing Zhang Zhibin Huang division of Cell Developmental and Integrative BiologySchool of MedicineSouth China University of TechnologyGuangzhouChina

Background:Despite the success of tyrosine kinase inhibitors in chronic myeloid leukemia(CML)therapy,CML still faces the challenges of drug resistance and progression to blast crisis.Twenty-five percent of patients have imatinib resistance and treatment difficulties due to heterogeneity after progression,but little is known about the mechanism.A key transcription factor in hematopoiesis,MYB,has been reported to increase abnormally in several types of aggressive blood disorders including CML.Methods:This study used a zebrafish model to explore the relationship between BCR/ABL1 and c-myb in CML progression.A CML zebrafish model was crossed with a c-myb hyperactivity transgenic line.Results:It was found that both exogenous BCR/ABL1 and c-myb could up-regulate the expression of neutrophil-related genes.More seriously,neutrophil accumulation was observed when BCR/ABL1 was combined with c-myb overexpression.Further studies showed that c-myb may be one of the downstream targets of BCR/ABL1 and the effect of BCR/ABL1 on neutrophils was c-myb dependent.Taking advantage of this inheritable in vivo model,it was shown that a combination of imatinib and flavopiridol,a cyclin-dependent kinase inhibitor targeting MYB,could more effectively alleviate the aggressive phenotype of the double transgene line.Conclusion:In summary,this study suggests that c-myb acts downstream of BCR/ABL1 and is involved in CML progression and is therefore a risk factor and a valuable target for the treatment of CML progression.The model used in the study could be helpful in high-throughput drug screening in CML transformation.

关键词： chronic myeloid leukemia c-myb flavopiridol zebrafish model

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Impact of vaccination on the dynamics of COVID-19:A mathematical study using fractional derivatives

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International Journal of Biomathematics 2024年第2期17卷 201-232页

作者： Shraddha Ramdas Bandekar Mini Ghosh C.Rajivganthi division of Mathematics School of Advanced Sciences Vellore Institute of TechnologyChennaiIndia

Arrival of a new disease marks a yearlong destruction of human lives and economy in general,and if the disease turns out to be a pandemic the loss is frightening.COVID-19 is one such pandemic that has claimed millions of lives till date.There is a suffering throughout the world due to various factors associated with the pandemic,be it loss of livelihoods because of sudden shutdown of companies and lockdown,or loss of lives due to lack of medical aid and inadequate vaccination supplies.In this study,we develop a six-compartmental epidemiological model incorporating vaccination.The motivation behind the study is to analyze the significance of higher vaccination efficacy and higher rate of population getting vaccinated in controlling the rise in infectives and thereby the untimely demise of various individuals.The work begins with an ordinary differential equation model followed by stability analysis of the same,after which a fractional-order derivative model of the same is formulated and the existence of uniformly stable solution for the system is proved.In addition to this,we present the stability of the equilibria in general for the fractional model framed.The sensitivity analysis of the basic reproduction number along with its correlation with various parameters is presented.In addition to this,sensitivity of certain state variables in the fractional model with respect to different.fractional orders as well with respect to different infection rate is exhibited in this work.Factors related to lockdown and usage of face shields are incorporated in the entire study,and importance of these is highlighted in the study as well.The major takeaway from the study is that mere vaccination will not sufice in eradication of the virus.The vaccine efficacy plays a major role along with other intervention included in the model.The numerical simulations are carried out in MATLAB software using ode45 and fdel2.

关键词： Caputo fractional derivative basic reproduction number stability analysis sensitivityanalysis vaccination

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An analytical approach for the fractional-order Hepatitis B model using new operator

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International Journal of Biomathematics 2024年第1期17卷 177-198页

作者： Surath Ghosh division of Mathematics School of Advanced Sciences Vellore Institute of TechnologyChennaiIndia

In this work,the main goal is to implement Homotopy perturbation transform method(HPTM)involving Katugampola fractional operator.As an example,a fractional order Hepatitis model is considered to analyze the solutions.At first,the integer order model is converted to fractional order model in Caputo sense.Then,the new operator Katugampola fractional derivative is used to present the model.The new such kind of operator is illustrated in Caputo sense.HPTM is described to get the solution of the proposed model using the new kind of operator.Also,there are some analyses about the new kind of operator to prove the efficiency of the operator.

关键词： Caputo derivative Katugampola fractional derivative homotopy perturbation transform method Hepatitis B model

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Super-Resolution Fluorescence Microscopy for Cilia Investigation and Ciliopathy Diagnosis(Invited)

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激光与光电子学进展 2024年第6期61卷 260-271页

作者： Liu Zhen Wu Yang division of Life Science The Hong Kong University of Science and TechnologyHong KongChina

The last two decades have witnessed the invention and development of super-resolution microscopy(SRM)that breaks the diffraction limit of light and pushes the fluorescence microscopy resolution to several nanometers.While SRM is widely used in biological studies,such as resolving subdiffraction structures,molecular mapping,tracking single molecules,probing protein-protein interactions,and observing organelle dynamics,its direct application in translational medicine,such as disease diagnosis,is still preliminary.Despite their small size,cilia play a crucial role as organelles in cell signaling and motility,with defects in cilia leading to ciliopathy.Similar to other miniature organelles and macromolecular complexes,cilia are ideal for super-resolution imaging.In this review,we will 1)introduce cilia and ciliopathy,2)show how SRM extends our knowledge of cilia,and 3)focus on how SRM improves the diagnosis of motile ciliopathies.

关键词： diagnosis limit spite

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Super Resolution Fluorescence Microscopy for Cilia Investigation and Ciliopathy Diagnosis

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激光与光电子学进展 2024年

作者： Zhen LIU Yang WU division of Life Science The Hong Kong University of Science and Technology

The last two decades have witnessed the invention and development of superresolution microscopy(SRM), which breaks the diffraction limit of light and pushes the resolution of fluorescence microscopy to several nanometers. SRM is now widely applied in biological studies such as resolving subdiffraction structures, molecular mapping, single molecule tracking, probing protein-protein interactions, and observing organelle dynamics. However, its direct application in translational medicine such as disease diagnosis is still preliminary. Despite their small size, cilia play a crucial role as organelles in cell signaling and motility, and defects in cilia lead to ciliopathy. Like other miniature organelles and macromolecular complexes, cilia are ideal for superresolution imaging. In this review, we will 1) introduce cilia and ciliopathy, 2) show how SRM extends our knowledge of cilia, and 3) focus on how SRM improves the diagnosis of motile ciliopathies.

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Solid-state atomic hydrogen as a broad-spectrum RONS scavenger for accelerated diabetic wound healing

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National Science Review 2024年第2期11卷 196-206页

作者： Man Luo Qin Wang Gang Zhao Wei Jiang Cici Zeng Qingao Zhang Ruyu Yang Wang Dong Yunxi Zhao Guozhen Zhang Jun Jiang Yucai Wang Qing Zhu Key Laboratory of Precision and Intelligent Chemistry School of Chemistry and Materials Science University of Science and Technology of China Department of Radiology The First Affiliated Hospital of University of Science and Technology of China Division of Life Sciences and Medicine University of Science and Technology of China Shenzhen Senior High School Institute of Intelligent Innovation Henan Academy of Sciences

Hydrogen therapy shows great promise as a versatile treatment method for diseases associated with the overexpression of reactive oxygen and nitrogen species（RONS）. However, developing an advanced hydrogen therapy platform that integrates controllable hydrogen release, efficient RONS elimination, and biodegradability remains a giant technical challenge. In this study, we demonstrate for the first time that the tungsten bronze phase H0.53WO3（HWO） is an exceptionally ideal hydrogen carrier, with salient features including temperature-dependent highly-reductive atomic hydrogen release and broad-spectrum RONS scavenging capability distinct from that of molecular hydrogen. Moreover, its unique p H-responsive biodegradability ensures post-therapeutic clearance at pathological sites. Treatment with HWO of diabetic wounds in an animal model indicates that the solid-state atomic H promotes vascular formation by activating M2-type macrophage polarization and anti-inflammatory cytokine production, resulting in acceleration of chronic wound healing. Our findings significantly expand the basic categories of hydrogen therapeutic materials and pave the way for investigating more physical forms of hydrogen species as efficient RONS scavengers for clinical disease treatment.

关键词： atomic hydrogen RONS scavenger inflammatory regulation diabetic wound healing hydrogen therapy

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