Influence of Succinimide Dispersants on Film Formation, Friction and Antiwear Properties of Zinc Dialkyl Dithiophosphate

ZDDP (zinc dialkyldithiophosphate) is arguably the most successful antiwear additive ever employed in crankcase engine lubricants. It was originally used as an antioxidant and shortly afterwards recognized for its antiwear and extreme pressure properties. Unfortunately, another critical additive polyisobutylsuccinimide-polyamine (PIBSA-PAM), which is used as a dispersant in engine oils, is known to be antagonistic to ZDDP in terms of film formation, friction and wear. The mechanisms of this antagonism have been widely studied, but they are still not well understood. Furthermore, in order to protect engine exhaust catalysts from sulphated ash, phosphorus and sulphur (SAPS) and extend drain intervals of engine lubricants, a progressive reduction in ZDDP quantity but a growth in the use of PIBSA-PAM is required. The aim of this study is to explore the mechanisms and practical effects of the antagonism between ZDDP and PIBSA-PAM. Of particular interest is the impact on performance of the ratio of ZDDP to PIBSA-PAM, as measured by P:N ratio. Since ZDDP is a very effective antiwear additive, it produces only very low or "mild" rates of wear. To study this requires a new way to measure mild wear behaviour of formulated oils. Several techniques have been applied in this study to investigate the film formation, friction and wear properties of ZDDP- and/or PIBSA-PAM-containing oils. These include a new mild wear testing method, which is tested and developed using a range of different types of additives. It is found that the ratio of P:N plays a strong role in determining tribofilm formation and friction of ZDDP/PIBSA-PAM blends. However it plays a much weaker role in determining wear behaviour. It is found that some PIBSA-PAMs have considerable friction-reducing properties in their own right. The results suggest that PIBSA-PAM may interfere with the behaviour of ZDDP in several ways: by forming a ZDDP/ PIBSA-PAM complex at the metal surfaces to reduce the local activity of ZDDP; by PIBSA-PAM partially removing the ZDDP film; possibly also by PIBSA-PAM blocking ZDDP from metal surfaces. The newly-developed wear testing method can be used conveniently and effectively to study mild wear properties not just of ZDDP but of a wide range of other additives

Rare Events and Scale--Invariant Dynamics of Perturbations in Delayed Dynamical Systems

We study the dynamics of perturbations in time delayed dynamical systems. Using a suitable space-time coordinate transformation, we find that the time evolution of the linearized perturbations (Lyapunov vector) can be mapped to the linear Zhang surface growth model [Y.-C. Zhang, J. Phys. France {\bf 51}, 2129 (1990)], which is known to describe surface roughening driven by power-law distributed noise. As a consequence, Lyapunov vector dynamics is dominated by rare random events that lead to non-Gaussian fluctuations and multiscaling properties.Comment: Final version to appear in Phys. Rev. Lett., 4 pages, 3 eps fig

Graphical condensation of plane graphs: a combinatorial approach

The method of graphical vertex-condensation for enumerating perfect matchings of plane bipartite graph was found by Propp (Theoret. Comput. Sci. 303(2003), 267-301), and was generalized by Kuo (Theoret. Comput. Sci. 319 (2004), 29-57) and Yan and Zhang (J. Combin. Theory Ser. A, 110(2005), 113-125). In this paper, by a purely combinatorial method some explicit identities on graphical vertex-condensation for enumerating perfect matchings of plane graphs (which do not need to be bipartite) are obtained. As applications of our results, some results on graphical edge-condensation for enumerating perfect matchings are proved, and we count the sum of weights of perfect matchings of weighted Aztec diamond.Comment: 13 pages, 5 figures. accepted by Theoretial Computer Scienc

HiPSC-derived cardiac tissue for disease modeling and drug discovery

Li, J.; Hua, Y.; Miyagawa, S.; Zhang, J.; Li, L.; Liu, L.; Sawa, Y. hiPSC-Derived Cardiac Tissue for Disease Modeling and Drug Discovery. Int. J. Mol. Sci. 2020, 21, 8893

Sudden jumps and plateaus in the quench dynamics of a Bloch state

We take a one-dimensional tight binding chain with periodic boundary condition and put a particle in an arbitrary Bloch state, then quench it by suddenly changing the potential of an arbitrary site. In the ensuing time evolution, the probability density of the wave function at an arbitrary site \emph{jumps indefinitely between plateaus}. This phenomenon adds to a former one in which the survival probability of the particle in the initial Bloch state shows \emph{cusps} periodically, which was found in the same scenario [Zhang J. M. and Yang H.-T., EPL, \textbf{114} (2016) 60001]. The plateaus support the scattering wave picture of the quench dynamics of the Bloch state. Underlying the cusps and jumps is the exactly solvable, nonanalytic dynamics of a Luttinger-like model, based on which, the locations of the jumps and the heights of the plateaus are accurately predicted.Comment: final versio

Agricultural Engineering in China

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 5 (2003): X. Zhou, R. Dong, S. Li, G. Peng, L. Zhang, J. Hou, J. Xiao and B. Zhu. Agricultural Engineering in China. Vol. V. September 2003

Citizen Willingness to Pay for the Implementation of Urban Green Infrastructure in the Pilot Sponge Cities in China

Urban green infrastructure has been widely used to in cities to solve stormwater problems caused by extreme weather events and urbanization around the world. However, the lack of a long-term funding mechanism for performing urban green infrastructure's functions has limited wider implementation. Factors influencing citizen attitudes and willingness to pay for urban green infrastructure vary from city to city. This study estimated the public's willingness to pay for urban green infrastructure, as well as compared the selected influencing factors of willingness to pay in different Chinese pilot sponge cities. The results show that 60% to 75% of all respondents in the cities were willing to support the implementation of urban green infrastructure in sponge cities, with those most willing to pay around 0-5 RMB/month (0-0.72 USD/month). The respondents' educational level was a significant influencing factor for their willingness to pay in all six cities, but age, gender and family monthly income correlated differently with respondents' willingness to pay in different cities. Previous knowledge of the sponge city concept and sponge city construction in the community were not significantly correlated with residents' willingness to pay. We conclude that local governments in China need to provide more information to the general public about the multiple ecosystem services, e.g., educational and recreational benefits, that urban green infrastructure can provide. In doing so, it will help a shift to urban green infrastructure as the solution to dealing with urban stormwater problems

Newer imaging modalities to identify high-risk ambulatory patients with heart failure

The lack of widely accepted objective measures of cardiac dysfunction other than left ventricular ejection fraction (LVEF) has hampered, and continues to hamper, clinical research in patients with heart failure (HF). Identifying patients at higher risk of adverse outcome would allow better targeting of therapy to those with most to gain.The thesis is divided in three parts.In the first part, I report the results of studies of the association between echocardiographic measures of right atrial pressure (by measuring the inferior vena cava (IVC) diameter) and outcome in ambulatory patients with HF. I also studied the associations with prognosis of a newer echocardiographic method (global longitudinal strain, GLS) to assess left ventricular systolic function in patients with normal LVEF on conventional imaging. In the second part, I report the results of studies of the associations of left atrial function by cardiac magnetic resonance (cMRI) with outcome in ambulatory patients with HF. I also studied the relationship between QRS morphology on ECG with cardiac structure and function measured by cMRI in ambulatory patients with HF.In the third part, I report the results of developing and prospectively evaluating an ultrasound method to measure the internal jugular vein diameter (as an objective estimate of the right atrial pressure) and its changes with respiratory manoeuvres.I studied the association between the jugular vein diameter, clinical and echocardiographic variables, and its relations with outcome in ambulatory patients with HF and controls.My results showed that upstream consequences of a dysfunctional left ventricle, such as impaired left atrial function measured by cMRI, a distended IVC or internal jugular vein by ultrasound, provide powerful prognostic information, similar to that obtained by measuring N-terminal pro-B-type natriuretic peptide plasma levels, in individuals with HF regardless of whether they have a reduced or normal LVEF.As residual congestion (dilated IVC or jugular vein) and impaired left atrial function appear strongly related to an adverse outcome, tailoring treatment to minimise congestion or improving left atrial function is an attractive concept worth testing.Published articles:1) Pellicori P, Carubelli V, Zhang J, Castiello T, Sherwi N, Clark AL, Cleland JG. IVC diameter in patients with chronic heart failure: relationships and prognostic significance. JACC Cardiovasc Imaging. 2013;6:16-28.http://doi.org/10.1016/j.jcmg.2012.08.012http://www.sciencedirect.com/science/article/pii/S1936878X120087902) Pellicori P, Kallvikbacka-Bennett A, Khaleva O, Carubelli V, Costanzo P, Castiello T, Wong K, Zhang J, Cleland JG, Clark AL. Global longitudinal strain in patients with suspected heart failure and a normal ejection fraction: does it improve diagnosis and risk stratification? Int J Cardiovasc Imaging. 2014;30:69-79.http://doi.org/10.1007/s10554-013-0310-yhttps://link.springer.com/article/10.1007/s10554-013-0310-y3) Pellicori P, Zhang J, Lukaschuk E, Joseph AC, Bourantas CV, Loh H, Bragadeesh T, Clark AL, Cleland JG. Left atrial function measured by cardiac magnetic resonance imaging in patients with heart failure: clinical associations and prognostic value. Eur Heart J. 2015;36:733-42.https://doi.org/10.1093/eurheartj/ehu405https://academic.oup.com/eurheartj/article/36/12/733/2293211/Left-atrial-function-measured-by-cardiac-magnetic?searchresult=14) Pellicori P, Joseph AC, Zhang J, Lukaschuk E, Sherwi N, Bourantas CV, Loh H, Clark AL, Cleland JG. The relationship of QRS morphology with cardiac structure and function in patients with heart failure. Clin Res Cardiol. 2015;104:935-45.http://doi.org/10.1007/s00392-015-0861-0https://link.springer.com/article/10.1007/s00392-015-0861-05) Pellicori P, Kallvikbacka-Bennett A, Zhang J, Khaleva O, Warden J, Clark AL, Cleland JG. Revisiting a classical clinical sign: jugular venous ultrasound. Int J Cardiol. 2014;170:364-70.http://doi.org/10.1016/j.ijcard.2013.11.015http://www.sciencedirect.com/science/article/pii/S01675273130198766) Pellicori P, Kallvikbacka-Bennett A, Dierckx R, Zhang J, Putzu P, Cuthbert J, Boyalla V, Shoaib A, Clark AL, Cleland JG. Prognostic significance of ultrasound-assessed jugular vein distensibility in heart failure. Heart. 2015;101:1149-58.http://dx.doi.org/10.1136/heartjnl-2015-307558http://heart.bmj.com/content/101/14/114