Methanol formation chemistry with revised reactions scheme

The aim of the presented work is to analyze the impact of experimentally evaluated reactions of hydrogen abstraction on surfaces of interstellar grains on the chemical evolution of methanol and its precursors on grains and in the gas phase under conditions of a cold dark cloud and during the collapse of a translucent cloud into a dark cloud. Analysis of simulation results shows that those reactions are highly efficient destruction channels for HCO and H2CO on grain surfaces, and significantly impact the abundances of almost all molecules participating in the formation of CH3OH. Next, in models with those reactions, maximum abundances of methanol in gas and on grain surfaces decrease by more than 2–3 orders of magnitude in comparison to models without surface abstraction reactions of hydrogen. Finally, we study the impact of binding energies of CH2OH and CH3O radicals on methanol chemistry.

A Chemical Reactor Network for Oxides of Nitrogen Emission Prediction in Gas Turbine Combustor

This study presents the use of a new chemical reactor network(CRN) model and non-uniform injectors to predict the NOx emission pollutant in gas turbine combustor. The CRN uses information from Computational Fluid Dynamics(CFD) combustion analysis with two injectors of CH4-air mixture. The injectors of CH4-air mixture have different lean equivalence ratio, and they control fuel flow to stabilize combustion and adjust combustor's equivalence ratio. Non-uniform injector is applied to improve the burning process of the turbine combustor. The results of the new CRN for NOx prediction in the gas turbine combustor show very good agreement with the experimental data from Korea Electric Power Research Institute.

Light-Controlled Chemical Reaction Pathways in Disulfide-Based Nonequilibrium Systems

Pathway selection in a complex chemical reaction network(CRN)enables organisms to adapt,evolve,and even learn in response to changing environments.Inspired by this,herein we report an artificial system,where light signal was used to manipulate the reaction pathways in a disulfide-based nonequilibrium CRN.By changing the photon energy and irradiation window,the anion or new radical-mediated pathways were selectively triggered,resulting in a user-defined evolution pathway.Additional photodissipative cycles were achieved by UV(365 nm)irradiation,increasing the total number of reactions from 3 to 7.The emerging pathway selection of the CRN is accurately predictable and controllable even in complex organo-hydrogel materials.We demonstrate up to five-state autonomous sol-gel transitions and the formation of fuel-driven dissipative organo-hydrogel through both chemical and light input.This work represents a new approach to allowing CRNs to communicate with the environment that can be used in the development of materials with lifelike behaviors.

Comfortable Lifestyle-induced Imbalance of Neuro-endocrine-immunity Network:A Possible Mechanism of Vascular Endothelial Dysfunction

Objective： To observe the changes of vascular endothelial functions and general neuroendocrine-immunity （NEI） network under the state of qi-deficiency syndrome induced by excessive idleness and to approach their internal relevance and illuminate initially the pathophysiological mechanism of vascular lesion induced by excessive idleness. Methods： A total of 100 male Wistar rats were randomly divided into the control group and the qi-deficiency syndrome model group, 50 rats in each group. The qi-deficiency syndrome model was established by feeding the animals with hyper-alimentation diet in combination with restricting movement for 10 weeks. Changes of common chemical signal molecules related to NEI and vascular endothelial functions were measured by the end of the experiment. Furthermore, their internal relevance was analyzed by the method of canonical correlation analysis. Results： The vascular endothelial structure and function were obviously injured in the model group. Compared with the control group, the chemical signal molecules, such as 5-hydroxytryptamine （5-HT）, corticosterone （CORT）, triiodothyronine （T3）, tetraiodothyronine （T4）, angiotensin Ⅱ （Ang Ⅱ）, interleukin-1 （IL-1）, and tumor necrosis factor-α （TNF-α） in peripheral blood of the model group （n=43） were changed significantly （P〈0.05 or P〈0.01）. Canonical correlation analysis showed that vascular endothelial dysfunction was correlated to the changes of these signal molecules in the NEI network. Conclusions： Comfortbased lifestyle induced not only vascular endothelial dysfunction but also an imbalance of the NEI network. Vascular endothelial dysfunction and the imbalanced NEI network interacted with each other, and an imbalance of the NEI network may be the pathophysiologic basis for the genesis and development of vascular endothelial dysfunction, even diseases of the blood vessel.

Fluctuation theorem for entropy production in a chemical reaction channel

Fluctuation theorem for entropy production in a mesoscopic chemical reaction network is discussed. When the system size is sufficiently large, it is found that, by defining a kind of coarse-grained dissipation function, the entropy production in a reversible reaction channel can be approximately described by a type of detailed fluctuation theorem. Such a fluctuation relation has been successfully tested by direct simulations in a linear reaction model consisting of two reversible channels and in an oscillatory model wherein only one channel is reversible.

Numerical and experimental investigation on emission performance of a fuel staged combustor

The low NOx emission technology has become an important feature of advanced aviation engine.A wide range of applications attempt to take advantage of the fact that staged combustion under lean-premixed-prevaporized(LPP)conditions can significantly cut down emission and improve combustion efficiency.This paper proposes a scheme with fuel centrally staged and multi-point injection.The mixing of fuel and air is improved,and the flame temperature is relative low in combustion zone,minimizing the formation of nitrogen oxides(NOx),especially thermal NOx.In terms of the field distribution of equivalence ratio and temperature obtained from Computational Fluid Dynamics(CFD),a chemical reactor network(CRN),including several different ideal reactor,namely perfectly stirred reactor(PSR)and plug flow reactor(PFR),is constructed to simulate the combustion process and predict pollution emission.The influences of the pilot equivalence ratio and percentage of pilot/main fuel on NOx and carbon monoxide(CO)emission were investigated by CRN model.The effects of the pilot fuel and primary fuel on pollution emission were investigated experimentally.Finally,the effects of pilot equivalence ratio and pilot fuel proportion on NOx emission were discussed in detail by comparing predict of CRN and experimental results.

Effect of Steam Dilution on the MILD Combustion Characteristics of Methane in a Model Combustor

Moderate or Intense Low-oxygen Dilution(MILD)combustion has low emission potential in gas turbines.The present work has investigated the performance of MILD combustion with parallel-jet burner arrangement in dry and steam-diluted conditions.The combustion tests were conducted in atmospheric pressure at various equivalence ratios from LBO(Lean Blow Out)to near-stoichiometric conditions and steam-to-air mass ratios from 0 to 0.2.A simplified chemical reactors network(CRN)model based on MILD combustion concept has been established to study the effect of steam dilution on different pathways of NO production.The experimental results show that under the same adiabatic flame temperature,the reaction zone gradually moves downstream with the increase of steam content.For the high steam content(0.2 kg/kg),the reaction zone is widely distributed,and the distribution of reaction intensity in the reaction zone is more uniform.The average lift-off height of reaction zone is proportional to the steam content.For the steam content of 0.2 kg/kg,the average lift-off height reaches 2.5 times that of the dry conditions,which brings the risk of blowout.For the adiabatic flame temperature of 1650–1900 K,the emissions of NOxare below 3×10–6(at 15%O2,dry)when the steam content varies from 0 to 0.2 kg/kg,which indicates the ultra-low emissions can be obtained under large changes in steam content.For the inlet temperature of 381 K,as the steam content increases,the Prompt NO is dominant in the total NO production.Steam dilution results in a smaller operating range with lower CO emissions.When the steam content reaches 0.2 kg/kg,compared to the dry condition,the carbon monoxide emission increases significantly.In addition,the LBO equivalence ratio of combustion with larger steam content is significantly higher.

Stochastic equations for a self-regulating gene

Expression of cellular genes is regulated by binding of transcription factors to their promoter, either activating or inhibiting transcription of a gene. Particularly interesting is the case when the expressed protein regulates its own transcription. In this paper, the features of this self-regulating process are investigated. In the presented model here, the gene can be in two states. Either a protein is bound to its promoter or not. The steady state distributions of protein during and just before switching from one state to the next state are analyzed. Moreover, a powerful numerical method based on the corresponding master equation to compute the protein distribution in the steady state is presented and compared to an already-existing method. Additionally the special case of self-regulation, in which protein can only be produced, if one of these proteins is bound to the promoter region, is analyzed. Furthermore, a self-regulating gene is compared to a similar gene, which also has two states and produces the same amount of proteins but is not regulated by its protein-product.