Inference and uncertainty quantification of stochastic gene expression via synthetic models

Estimating uncertainty in model predictions is a central task in quantitative biology. Biological models at the single-cell level are intrinsically stochastic and nonlinear, creating formidable challenges for their statistical estimation which inevitably has to rely on approximations that trade accuracy for tractability. Despite intensive interest, a sweet spot in this trade-off has not been found yet. We propose a flexible procedure for uncertainty quantification in a wide class of reaction networks describing stochastic gene expression including those with feedback. The method is based on creating a tractable coarse-graining of the model that is learned from simulations, a synthetic model, to approximate the likelihood function. We demonstrate that synthetic models can substantially outperform state-of-the-art approaches on a number of non-trivial systems and datasets, yielding an accurate and computationally viable solution to uncertainty quantification in stochastic models of gene expression.     

A Recursive Orthogonal Least Squares Algorithm for Training RBF Networks

A recursive orthogonal least squares (ROLS) algorithm for multi-input, multi-output systems is developed in this paper and is applied to updating the weighting matrix of a radial basis function network. An illustrative example is given, to demonstrate the effectiveness of the algorithm for eliminating the effects of ill-conditioning in the training data, in an application of neural modelling of a multi-variable chemical process. Comparisons with results from using standard least squares algorithms, in batch and recursive form, show that the ROLS algorithm can significantly improve the neural modelling accuracy. The ROLS algorithm can also be applied to a large data set with much lower requirements on computer memory than the batch OLS algorithm.     

技术变革带来污水汽提装置能耗显着下降

本文论述的污水汽提装置采取了一系列改进措施。不仅处理后水质大为改观，而且蒸汽、电和水的消耗显著下降，尤其是蒸汽单耗达到了６０ｋｇ／ｔ污水，在石化总公司居领先水平。     

微波放电NO-O2-H2O-He体系脱除NO的数值模拟

采用微波放电NO-O2-H2O-He体系脱除NO的反应模型,对NO脱除及其转化进行分析计算。通过建立并数值求解化学反应动力学方程组,对NO-O2-H2O-He体系微波直接分解脱除NO过程进行反应动力学研究,分析影响NO脱除效率及其向N2和NO2转化的各种因素及规律。计算结果表明,在NO-O2-H2O-He体系中,微波功率,NO、O2和H2O的初始浓度等对NO脱除效率有较大影响,即微波功率的增大有利于NO的脱除及其向N2的转化;NO初始浓度的增加降低了体系的微波脱硝效率;脱硝效率随着模拟烟气相对湿度的增加而增加;微波放电条件下,O2的加入可增加产物中NO2的生成量;微波放电NO-O2-H2O-He体系脱除NO为还原和氧化反应共同作用的结果,NO转化为N2的效率总大于其转化为NO2的效率。     

300MW锅炉临炉加热系统改造分析

针对大唐河北发电有限公司马头热电分公司2台300MW锅炉启动时间较长的问题,从锅炉运行、设计两方面分析原因,提出改造锅炉底部加热系统的方案,并说明改造效果及改造效益.     

有机化工废水COD与TOC的相关性

研究了有机化工废水COD与TOC的相关性。用Rosemount DC-85A有机总碳测定仪测定了有机废水的TOC,并通过TOC回归方程(COD=a+bTOC)的表达,发现它们有很好的相关性。可以用TOC值作有机化工废水污染的快速监测。     

The effects of process conditions and substrate on copper MOCVD using liquid injection of (hfac)Cu(vtmos)

Copper MOCVD (metalorganic chemical vapor deposition) using liquid injection for effective delivery of the (hfac)Cu(vtmos) [1,1,1,5,5,5-hexafluoro-2,4-pentadionato(vinyltrimethoxysilane) copper(I)] precursor has been performed to clarify growth behavior of copper films onto TiN, <100> Si, and Si₃N₄ substrates. Especially, we have studied the influences of process conditions and the substrate on growth rates, impurities, microstructures, and electrical characteristics of copper films. As the reactor pressure was increased, the growth rate was governed by a pick-up rate of (hfac)Cu(vtmos) in the vaporizer. The apparent activation energy for copper growth over the surface-reaction controlled regime from 155°C to 225°C was in the range 12.7–32.5 kcal/mol depending upon the substrate type. It revealed that H₂ addition at 225°C substrate temperature brought about a maximum increase of about 25% in the growth rate compared to pure Ar as the carrier gas. At moderate deposition temperatures, the degree of a <111> preferred orientation for the deposit was higher on the sequence of <Cu/Si<Cu/TiN<Cu/Si₃N₄. The relative impurity content within the deposit was in the range 1.1 to 1.8 at.%. The electrical resistivity for the Cu films on TiN illustrated three regions of the variation according to the substrate temperature, so the deposit at 165°C had the optimum resistivity value. However, the coarsened microstructures of Cu on TiN prepared above 275°C gave rise to higher electrical resistivities compared to those on Si and Si₃N₄ substrates.     

Improved arsenic doping in metalorganic chemical vapor deposition of HgCdTe andin situ growth of high performance long wavelength infrared photodiodes

Controlled and effective p-type doping is a key ingredient forin situ growth of high performance HgCdTe photodiode detectors. In this paper, we present a detailed study of p-type doping with two arsenic precursors in metalorganic chemical vapor deposition (MOCVD) of HgCdTe. Doping results from a new precursortris-dimethylaminoarsenic (DMAAs), are reported and compared to those obtained from tertiarybutylarsine (TBAs). Excellent doping control has been achieved using both precursors in the concentration range of 3 × 1015-5 × 10¹⁷ cm⁻³ which is sufficient for a wide variety of devices. Arsenic incorporation efficiency for the same growth temperature and partial pressure is found to be higher with DMAAs than with TBAs. For doping levels up to 1 × 10₁₇ cm⁻³, the alloy composition is not significantly affected by DMAAs. However, at higher doping levels, an increase in the x-value is observed, possibly as a result of surface adduct formation of DMAAs dissociative products with dimethylcadmium. The activation of the arsenic as acceptors is found to be in the 152–50% range for films grown with DMAAs following a stoichiometric anneal. However, a site transfer anneal increases the acceptor activation to near 100%. Detailed temperature dependent Hall measurements and modeling calculations show that two shallow acceptor levels are involved with ionization energies of 11.9 and 3.2 meV. Overall, the data indicate that DMAAs results in more classically behaved acceptor doping. This is most likely because DMAAs has a more favorable surface dissociation chemistry than TBAs. Long wavelength infrared photodiode arrays were fabricated on P-on-n heterojunctions, grownin situ with iodine doping from ethyl iodide and arsenic from DMAAs on near lattice matched CdZnTe (100) substrates. At 77K, for photodiodes with 10.1 and 11.1 (im cutoff wavelengths, the average (for 100 elements 60 × 60 μm² in size) zero-bias resistance-area product, R₀A are 434 and 130 ohm-cm², respectively. Quantum efficiencies are ≥50% at 77K. These are the highest R₀A data reported for MOCVDin situ grown photodiodes and are comparable to state-of-the-art LPE grown photodiodes processed and tested under identical conditions.     

斜坡非饱和带低渗透岩石中水气分子的扩散机理

根据分子运动论,对水气分子在低渗透岩石中的扩散模式进行研究,得出水气分子中的主要气体H2O、CO2以及O2在新鲜二长岩和玄武岩中的扩散为过渡型扩散.通过计算得到三者的有效扩散系数.以微砂质细粒长石石英砂岩为研究对象,在电子显微镜下获得砂岩的铸体薄片图像,并对其进行处理,建立砂岩的二维孔隙扩散模型,模拟岩石风化过程中水气分子在砂岩孔隙内的扩散过程,得到砂岩模型内部的速度分布图、压力分布图和雷诺数图.结果表明,天然状态下,水气分子的流动主要出现在胶结物受腐蚀的风化区域.胶结物溶蚀产生的贯通孔隙是水气分子的主要扩散通道和贮存场所.水气分子在砂岩内部孔隙中的流动符合流体流动的基本规律,雷诺数的量级为10-3,流动状态为层流.同时对风化岩石的剖面进行分带,分析了水气分子扩散对岩石风化产生的影响.     

CO2激光诱导液相沉积银的机理研究

激光诱导液相沉积的机理可大致分为光电化学机理、热电化学机理和热分解机理等。通过试验及分析表明 ,CO2 激光诱导液相沉积银属于简单的热分解机理。CO2 激光起到局域热源的作用 ,在激光辐照过程中 ,光照区介质溶液及基体表面均发生了极其复杂的物理化学变化 ,最后诱导产生的银沉积在基体表面并部分扩散到了基体内部 ,成为后续化学镀铜的催化中心及过渡层