Corrosion Resistant Nickel-Based Alloy

A nickel based, high silicon alloy exhibits very high corrosion resistance in high temperature sulfuric acid environments. The alloy may be cast and is sufficiently ductile to be fabricated and machined. The alloy is ductile and has sufficient resistance to mechanical and thermal shock to be reliable in service when used as rotating parts

The development of nickel silicide based alloy for sulfuric acid application

“The present project has been supported by Chas S Lewis Co. Inc. to try to develop a cast alloy that has acceptable mechanical properties and excellent resistance to corrosion by sulfuric acid over the entire concentration range (especially for the concentrations between 60 and 80 wt%) at their boiling temperatures. Also, the alloy should have good machinability and weldability, and be economically viable. It is known that Ni3Si-based alloys have good corrosion resistance in concentrated sulfuric acids, but they are very brittle. In the present study, Ni3Si-based alloys with Ti, Nb, Cu, Cr and Mo additions have been cast and studied with SEM, DTA, AES, and optical microscopy. Their mechanical properties and corrosion resistance in boiling sulfuric acids with different heat treatments have been investigated. It has been found that alloys NiSi20Nb3B0.5, NiS20.4Nb2B0.5, and NiSi20.2Nb2.5B0.5 have acceptable mechanical properties, machinability, and weldability, and have better corrosion resistance in boiling 60%, 70%, and 80% sulfuric acid than any other existing alloys. The effects of Ti, Nb, Cu, Cr, and Mo additions on the microstructure and corrosion resistance of the alloys have been studied. It was found that Ti additions encouraged the formation of the Ni3Si β phase, but the β phase with Ti addition had very poor corrosion resistance. Nb addition increased the ductility and the corrosion resistance of the alloy. Cu, Cr and Mo additions encouraged the formation of the α and γ phases (the former phase usually decreased the corrosion resistance, the latter hurt mechanical properties). An investigation of the weldability of the alloys showed that the as-cast NiSi20Nb3B0.5 alloy could be successfully welded using 600°C preheat and NiSi20Nb3B0.5 welding rods produced by centrifugal casting. Effects of the G phase (Ni16Si7Nb6) on the corrosion resistance and mechanical properties, corrosion resistance mechanism, and polarization behavior of the alloys were also investigated”--Abstract, page iii

The Development Trends of Fuel Cell Technologies Based on Patent Analysis

Fuel cells are made from fuel and oxygen. Because of its low pollution, high energy conversion efficiency and high reliability, fuel cell has become the future direction of new energy application, the technological development path in the field of fuel cell research has great significance to the development of technological and energy innovation. Using the patent analysis method, this paper analyses the patent data from Derwent Innovation Index quantitively to study the state of application for patents, core technologies, highly cited patents and the main patentees. It shows that auxiliary device and related methods were a research hotspot in recent years; as the biggest patent holder of fuel cell technologies, Toyota, Honda motor Co. and Nissan motor Co. have an advantage. This paper has discovered some potential problems behind the phenomena and some suggestions are put forward finally

Nonlinear dynamics of avian influenza epidemic models

•Avian influenza A H1N1 and H7N9 have resulted significant human cases.•Construct avian influenza models with different avian growth laws.•Analyze the dynamical behavior of these models completely.•Obtain the threshold value for the prevalence of avian influenza .•Discuss the occurrence of periodic solutions with avian Allee effect. Avian influenza is a zoonotic disease caused by the transmission of the avian influenza A virus, such as H5N1 and H7N9, from birds to humans. The avian influenza A H5N1 virus has caused more than 500 human infections worldwide with nearly a 60% death rate since it was first reported in Hong Kong in 1997. The four outbreaks of the avian influenza A H7N9 in China from March 2013 to June 2016 have resulted in 580 human cases including 202 deaths with a death rate of nearly 35%. In this paper, we construct two avian influenza bird-to-human transmission models with different growth laws of the avian population, one with logistic growth and the other with Allee effect, and analyze their dynamical behavior. We obtain a threshold value for the prevalence of avian influenza and investigate the local or global asymptotical stability of each equilibrium of these systems by using linear analysis technique or combining Liapunov function method and LaSalle’s invariance principle, respectively. Moreover, we give necessary and sufficient conditions for the occurrence of periodic solutions in the avian influenza system with Allee effect of the avian population. Numerical simulations are also presented to illustrate the theoretical results

On avian influenza epidemic models with time delay

Abstract After the outbreak of the first avian influenza A virus (H5N1) in Hong Kong in 1997, another avian influenza A virus (H7N9) crossed the species barrier in mainland China in 2013 and 2014 and caused more than 400 human cases with a death rate of nearly 40 %. In this paper, we take account of the incubation periods of avian influenza A virus and construct a bird-to-human transmission model with different time delays in the avian and human populations combining the survival probability of the infective avian and human populations at the latent time. By analyzing the dynamical behavior of the model, we obtain a threshold value for the prevalence of avian influenza and investigate local and global asymptotical stability of equilibria of the system

Global Dynamics of Avian Influenza Epidemic Models with Psychological Effect

Cross-sectional surveys conducted in Thailand and China after the outbreaks of the avian influenza A H5N1 and H7N9 viruses show a high degree of awareness of human avian influenza in both urban and rural populations, a higher level of proper hygienic practice among urban residents, and in particular a dramatically reduced number of visits to live markets in urban population after the influenza A H7N9 outbreak in China in 2013. In this paper, taking into account the psychological effect toward avian influenza in the human population, a bird-to-human transmission model in which the avian population exhibits saturation effect is constructed. The dynamical behavior of the model is studied by using the basic reproduction number. The results demonstrate that the saturation effect within avian population and the psychological effect in human population cannot change the stability of equilibria but can affect the number of infected humans if the disease is prevalent. Numerical simulations are given to support the theoretical results and sensitivity analyses of the basic reproduction number in terms of model parameters that are performed to seek for effective control measures for avian influenza

The Cost-Effectiveness Analysis and Optimal Strategy of the Tobacco Control

This paper aims at investigating how the media coverage and smoking cessation treatment should be implemented, for a certain period, to reduce the numbers of smokers and patients caused by smoking while minimizing the total cost. To this end, we first propose a new mathematical model without any control strategies to investigate the dynamic behaviors of smoking. Furthermore, we calculate the basic reproduction number R0 and discuss the global asymptotic stabilities of the equilibria. Then, from the estimated parameter values, we know that the basic reproduction number R0 is more than 1, which reveals that smoking is one of the enduring problems of the society. Hence, we introduce two control measures (media coverage and smoking cessation treatment) into the model. Finally, in order to investigate their effects in smoking control and provide an analytical method for the strategic decision-makers, we apply a concrete example to calculate the incremental cost-effectiveness ratios and analyze the cost-effectiveness of all possible combinations of the two control measures. The results indicate that the combination of media coverage and smoking cessation treatment is the most cost-effective strategy for tobacco control

Molecular mechanisms of ferroptosis and its antitumor applications in natural products

Ferroptosis, an iron-dependent form of regulated cell death, results in lipid peroxidation of polyunsaturated fatty acids in the cell membrane, which is catalyzed by iron ions and accumulated to lethal levels. It is mechanistically distinct from other forms of cell death, such as apoptosis, pyroptosis, and necroptosis, so it may address the problem of cancer resistance to apoptosis and provide new therapeutic strategies for cancer treatment, which has been intensively studied over the past few years. Notably, considerable advances have been made in the antitumor research of natural products due to their multitargets and few side effects. According to research, natural products can also induce ferroptosis in cancer therapies. In this review we summarize the molecular mechanisms of ferroptosis, introduce the key regulatory genes of ferroptosis, and discuss the progress of natural product research in the field of ferroptosis to provide theoretical guidance for research on natural product-induced ferroptosis in tumors