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Molecular behaviors in thin film lubrication——Part three: Superlubricity attained by polar and nonpolar molecules

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Friction 2019年第6期7卷 625-636页

作者： Xiangyu GE tobias HALMANS Jinjin LI Jianbin LUO State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China RWTH Aachen University Aachen 52062Germany

In thin-film lubrication(TFL), generally, the viscosity of the lubricant and its coefficient of friction(Co F) increase. Finding a method to reduce the Co F in TFL is a significant challenge for tribologists. In the present work, we report a robust superlubricity attained by using polyalkylene glycols(PAGs, polar molecules) and poly-α-olefins(PAOs, nonpolar molecules) as lubricants on steel/steel friction pairs that have been pre-treated by wearing-in with polyethylene glycol aqueous solution(PEG(aq)). A steady superlubricity state with a Co F of 0.0045 for PAG100 and 0.006 for PAO6 could be maintained for at least 1 h. Various affecting factors, including the sliding velocity, normal load, and viscosity of the lubricants, were investigated. Element analysis proved that composite tribochemical layers were deposited on the worn region after the treatment with PEG(aq). These layers were formed by the tribochemical reactions between PEG and steel and composed of various substances including oxides, iron oxides, Fe OOH, and Fe(OH)3, which contributed to the superlubricity. In addition to the tribochemical layers, ordered layers and a fluid layer were formed by the PAGs and PAOs during the superlubricity periods. All the three types of layers contributed to the superlubricity, indicating that it was attained in the TFL regime. Accordingly, a mechanism was proposed for the superlubricity of the PAGs and PAOs in the TFL regime in this work. This study will increase the scientific understanding of the superlubricity in the TFL regime and reveal, in the future, the potential for designing superlubricity systems on steel surfaces for industrial applications.

关键词： thin film lubrication superlubricity PEG PAG PAO

The Strategy of Escalation and Negotiation: The Iran Nuclear Dispute

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Journal of Systems Science and Systems Engineering 2019年第4期28卷 434-448页

作者： tobias W. Langenegger Keith W. Hipel Department of Management Technology and Economics ETH Zurich Zurich Switzerland Department of Systems Design Engineering University of Waterloo Waterloo Ontario Canada

The strategic decisions and resulting consequences surrounding the conflict between the United States of America (US) and Iran regarding the Iranian nuclear program are formally investigated using a flexible decision methodology called the Graph Model for Conflict Resolution (GMCR). This highly controversial dispute caught the world's attention as concerns were growing that Iran would reach a position where it would be able to build nuclear weapons, thereby posing a risk to world security. While Iran insisted on its rights for the peaceful use of nuclear technology;the international community;led by the US, tried to discourage the nuclear activities of Iran to ensure its obligations to the non-proliferation of nuclear weapons. This led to an escalation of tension on both sides, with an extension of the nuclear program by Iran and an increase in sanctions by the US, before it was possible to arrive at a negotiated agreement. As demonstrated in this paper, a systematic GMCR investigation provides valuable strategic insights into this important conflict. Further, it illustrates ways in which the conflict could have evolved, as well as mechanisms for stopping an escalation like this in the future.

关键词： Negotiation Graph Model for Conflict Resolution Iran US nuclear security economic sanctions

Embracing the Integrative

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Journal of Integrative Plant Biology 2013年第10期55卷 890-891页

作者： tobias I.Baskin Biology Department University of Massachusetts Amherst

My invitation to join the editorial board of Journal of Integrative Plant Biology （JIPB） brought back fond memories. In the early 1980＇s when I was a Ph.D. student, the library subscribed to Acta Botanica Sinica （as JIPB was then titled） and would put out current issues in the reading room. When I had finished reading each issue, I remember checking off my name on the strip of paper stapled to the cover. In those days, the journal published in Chinese, with English abstracts, and I saw papers that I wished I could read in full.

关键词： Embracing the Integrative

Rationally designed treatment for metastatic colorectal cancer:Current drug development strategies

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World Journal of Gastroenterology 2014年第30期20卷 10288-10295页

作者： Pavlina Spiliopoulou Hendrik-tobias Arkenau Drug Development Unit Sarah Cannon Research Institute United KingdomLondon W1G 6ADUnited Kingdom UCL Cancer Institute Medical OncologyUniversity College LondonLondon WC1E 6BTUnited Kingdom

The therapeutic landscape of metastatic colorectal cancer(mCRC)has changed substantially with the emergence of new molecularly targeted agents(MTA)usedas single agents or alongside standard *** use of these MTAs extended the overall survival ofpatients with mCRC to a level that current chemotherapeutics alone could not *** addition,improvement in surgical techniques and ablation modalities offer cure to a limited subset of patients with mCRC andMTAs have been found to have a significant role heretoo,as they aid ***,for the majority of patients,mCRC remains an invariably incurabledisease necessitating continued courses of combinedtreatment *** the course of these treatments,either cytotoxic or biological,cancer cells maintain their ability to acquire mitogenic mutations whichrender them resistant to *** challengesremain to identify appropriate subsets of patients whowill most likely benefit from these new MTAs and effectively select these based on validated ***,better knowledge of the biology of colorectal cancer and the mechanisms via which it bypasses blockade of known signalling pathways will help us design better and more rational sequencing of these treatments,so that we can maximise the survivorship of mCRC *** review outlines treatment strategies for known molecular alterations with new MTAs and highlights some promising strategies.

关键词： Colorectal cancer Molecularly targeted therapies Drug development

Upward organelle motility

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Journal of Integrative Plant Biology 2015年第1期57卷 2-3页

作者： tobias I.Baskin Centre for Plant Integrative Biology University of NottinghamUK Biology Department University of Massachusetts Amherst MA USA Professor Special Issue Editor

Eukaryotic cells contain a collection of membrane-bounded organelles, in addition to the nucleus, supporting the large size and diverse activities of this type of cell. Evolving with these compartments are filaments and enzymes that convert chemical energy into work （so-called motor proteins）, a network collectively termed the cytoskeleton. Whether it is a chloroplast moving to optimally intercept light or the endoplasmic reticulum deploying its cisternae to deliver secreted proteins, motility of organelles is an essential component of their function, and this motility is driven by the cvtoskeleton.

关键词： Upward organelle motility cell

Slice Thickness Optimization for the Focused Ion Beam-Scanning Electron Microscopy 3D Tomography of Hierarchical Nanoporous Gold

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Nanomanufacturing and Metrology 2022年第2期5卷 112-118页

作者： Alexander Shkurmanov tobias Krekeler Martin Ritter Electron Microscopy Unit Hamburg University of Technology(TUHH)Eißendorfer Straße 4221073HamburgGermany

The combination of focused ion beam (FIB) with scanning electron microscopy (SEM), also known as FIB-SEM tomography, has become a powerful 3D imaging technique at the nanometer scale. This method uses an ion beam to mill away a thin slice of material, which is then block-face imaged using an electron beam. With consecutive slicing along the z-axis and subsequent imaging, a volume of interest can be reconstructed from the images and further analyzed. Hierarchical nanoporous gold (HNPG) exhibits unique structural properties and has a ligament size of 15–110 nm and pore size of 5–20 nm. Accurate reconstruction of its image is crucial in determining its mechanical and other properties. Slice thickness is one of the most critical and uncertain parameters in FIB-SEM tomography. For HNPG, the slice thickness should be at least half as thin as the pore size and, in our approach, should not exceed 10 nm. Variations in slice thickness are caused by various microscope and sample parameters, e.g., converged ion milling beam shape, charging effects, beam drift, or sample surface roughness. Determining and optimizing the actual slice thickness variation appear challenging. In this work, we examine the influence of ion beam scan resolution and the dwell time on the mean and standard deviation of slice thickness. After optimizing the resolution and dwell time to achieve the target slice thickness and lowest possible standard deviation, we apply these parameters to analyze an actual HNPG sample. Our approach can determine the thickness of each slice along the z-axis and estimate the deviation of the milling process along the y-axis (slow imaging axis). For this function, we create a multi-ruler structure integrated with the HNPG sample.

关键词： Focused ion beam Scanning electron microscopy Tomography Hierarchical nanoporous gold

O05 e-alternatives-past, present and future

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中国药理通讯 2006年第2期23卷 4-5页

作者： David dewhurst Learning Technology Section College of Medicine ＆ Veterinary Medicine University of Edinburgh Edinburgh EH8 9XD UK.

Regulatory T cells in viral hepatitis

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World Journal of Gastroenterology 2007年第36期13卷 4858-4864页

作者： Eva Billerbeck tobias Bttler Robert Thimme Department of Medicine Ⅱ University Hospital Freiburg Germany

The pathogenesis and outcome of viral infections are significantly influenced by the host immune response. The immune system is able to eliminate many viruses in the acute phase of infection. However, some viruses, like hepatitis C virus (HCV) and hepatitis B virus (HBV), can evade the host immune responses and establish a persistent infection. HCV and HBV persistence is caused by various mechanisms, like subversion of innate immune responses by viral factors, the emergence of T cell escape mutations, or T cell dysfunction and suppression. Recently, it has become evident that regulatory T cells may contribute to the pathogenesis and outcome of viral infections by suppressing antiviral immune responses. Indeed, the control of HCV and HBV specific immune responses mediated by regulatory T cells may be one mechanism that favors viral persistence, but it may also prevent the host from overwhelming T cell activity and liver damage. This review will focus on the role of regulatory T cells in viral hepatitis.

关键词： Regulatory T cells Viral hepatitis Immunoregulation

Mixing Monte-Carlo and Partial Differential Equations for Pricing Options

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Chinese Annals of Mathematics,Series B 2013年第2期34卷 255-276页

作者： tobias LIPP Grgoire LOEPER Olivier PIRONNEAU LJLL-UPMC Boite 187Place Jussieu75252 Paris cedex 5France BNP-Paribas 20 Boulevard des Italiens75009 ParisFrance

There is a need for very fast option pricers when the financial objects are modeled by complex systems of stochastic differential *** the authors investigate option pricers based on mixed Monte-Carlo partial differential solvers for stochastic volatility models such as Heston'*** is found that orders of magnitude in speed are gained on full Monte-Carlo algorithms by solving all equations but one by a Monte-Carlo method,and pricing the underlying asset by a partial differential equation with random coefficients,derived by Ito *** strategy is investigated for vanilla options,barrier options and American options with stochastic volatilities and jumps optionally.

关键词： Monte-Carlo Partial differential equations Heston model Financial mathematics. Option pricing