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Parameter estimation is an important problem because in many instance uncertain parameters cannot be measured accurately, especially in real-time applications. Information about them is commonly inferred via parameter estimation techniques from available measurements of different aspects of the system response. In this work, we consider the reduction of the uncertain topography parameters of 2D shallow water equations to be inconsistency with the physical observations. This is often quite challenging due to its ill-posed nature of the inverse problem, particularly for the present nonlinear case in high-dimensional random space. We have explored an efficient computational strategy for the solution of the problem in the framework of the polynomial chaos (PC)-based ensemble Kalman filter (PC-EnKF for short). The main idea pursued in this methodology is to introduce a determination of the potential optimal observation location followed by the update of the input topography parameters to be retrieved through the PC-EnKF, wherein the identification of the optimal observation locations is accomplished sequentially via the predictive uncertainty controlled by standard deviation, and then places the corresponding measurement for data assimilation purpose. This is not only to provide more informative measurements but also to improve the topography parameters estimation. The numerical experiments indicate that the optimal observations-based PC-EnKF algorithm is effective in dealing with the current retrieval of topography parameters. It is worth mentioning that an iterative PC-basis rotation technique is particularly useful when attempting to enhance the sparsity and the resulting accuracy. The solution strategy is well suited in the current high-dimensional nonlinear inverse modeling and has shown its appealing potential in the real-world application of complex systems.

An elastic-net (EN) based polynomial chaos (PC) ensemble Kalman filter (PC-EnKF) with iterative PC-basis rotations is developed for high-dimensional nonlinear inverse modeling. To avoid the huge computational cost of estimating PC expansion coefficients and the Kalman gain matrix in PC-EnKF, this paper focuses mainly on solving the minimization problem of the elastic-net (EN) cost function with the fast iterative shrinkage-thresholding algorithm (FISTA). To further enhance the sparsity and accuracy, an iterative PC-basis rotation method is employed. When performing the rotation technique, two key issues need to be addressed to accommodate the computation of the inverse problem . One is the derivation of a new multi-dimensional random variable . This can be realized by exploring the construction of the gradient matrix used in a multi-parameter and vector-valued response model. The other issue is the selection of the number of iterative rotations during the process of each data assimilation, which can be addressed by resorting to a curve of sparsity versus the number of iterations. As for the regularization parameters, they can be tuned by calculating the information criteria (IC). Through the numerical examples, we demonstrate that EN-based PC-EnKF combined with the iterative PC-basis rotation method is well suited in the high-dimensional nonlinear inverse modeling, and has great potential in the high-dimensional nonlinear inverse modeling of real-world complex systems.

Diacetyl, a highly valuable product that is extensively used as an ingredient of food, tobacco, and daily chemicals such as perfumes, can be produced from the nonenzymatic oxidative decarboxylation of α-acetolactate during bacterial fermentation and converted to acetoin and 2,3-butanediol by 2,3-butanediol dehydrogenase. In the present study, Bacillus sp. DL01, which gives high acetoin production, was metabolically engineered to improve diacetyl production. After the deletion of α-acetolactate decarboxylase (ALDC)-encoding gene (alsD) by homologous recombination, the engineered strain, named Bacillus sp. DL01-ΔalsD, lost ALDC activity and produced 1.53 g/L diacetyl without acetoin and 2,3-butanediol accumulation. The channeling of carbon flux into diacetyl biosynthetic pathway was amplified by an overexpressed α-acetolactate synthase (ALS)-encoding gene (alsS) in Bacillus sp. DL01-ΔalsD-alsS, which produced 4.02 g/L α-acetolactate and 1.94 g/L diacetyl, and the conversion from α-acetolactate to diacetyl was increased by 1-fold after 20 mM Fe3+ was added to the fermentation medium. A titer of 8.69 g/L diacetyl, the highest reported diacetyl production, was achieved by fed-batch fermentation in optimal conditions using the metabolically engineered strain of Bacillus sp. DL01-ΔalsD-alsS. These results are of great importance as a new method for the efficient production of diacetyl by food-safe bacteria.

When parameter estimation is solved in a high-dimensional space, the dimensionality reduction strategy becomes the primary consideration for alleviating the tremendous computational cost. In the present study, the discrete empirical interpolation method (DEIM) is explored to retrieve the initial condition (IC) by combining the polynomial chaos (PC) based ensemble Kalman filter (i.e. PC-EnKF), where a non-intrusive PC expansion is considered as a surrogate model in place of the forward model in the prediction step of the ensemble Kalman filter, resulting in fewer forward model integrations but with a comparable accuracy as Monte Carlo-based approaches. The DEIM acts as a hyper-reduction tool to provide the low-dimensional input for the high-dimensional initial field, which can be reconstructed using the information on the sparse interpolation grid points that is adaptively obtained through PC-EnKF data assimilation method. Thus an innovative framework to reconstruct the IC is developed. The detailed procedure at each assimilation iteration includes: the determination of the spatial interpolation points, the estimation of the initial values on the interpolation locations using the optimal observations, and the reconstruction of IC in the full space. The current study uses the reconstruction field of initial conditions of the Navier-Stokes equations as an example to illustrate the efficacy of our method. The experimental results demonstrate the proposed algorithm achieves a satisfactory reconstruction for the initial field. The proposed method helps to extend the applicable area of DEIM in solving inverse problems.

Water-shale interaction remains an unsolved problem because of the complexity involved in the physical processes and the heterogeneity in the chemical composition and pore structure of rocks. By considering the basic physical properties of Longmaxi shale and performing a series of physical experiments representing the water-shale interaction, the relationship between the mineral composition and water-shale interaction, which is the process responsible for causing structural damage when water and shale interact, is analysed. The ion exchange of clay minerals occurs when shale makes contact with water and different kinds of cations experience different degrees of overflow in water-shale interaction. The charge of clay mineral changes during water-shale interaction, resulting in a change of the gravitational and repulsive forces between the particles. This leads to the passivation of the contour edges of clay minerals and changes in the mechanical properties. In a relatively short time, illite can produce a large hydration stress with a small expansion value, but the hydration speed of Na-montmorillonite (Na-MMT) is relatively slow. Uneven stress caused by the hydration of different clay minerals being soaked in different aqueous solutions can cause local stress concentration, further promote the expansion and increase of original micro-cracks in shale, and then appear as disordered macro-cracks. The macroscopic cracks also provide a channel for the continuous entry of working fluid. More water molecules enter the shale faster and make contact with clay particles, weakening the interaction and cementation between particles. Macroscopically, they are manifested as a decrease in the rock cohesion, internal friction angle, and compressive strength as well as a failure of the structural integrity. Different inorganic salt solutions have different inhibitory effects on reducing the hydration degrees of illite and Na-MMT. Therefore, the water-shale interaction of organic-rich shale is a process in which the microscopic damage of water to rock gradually evolves into macroscopic damage, and results in the local continuity loss of rock on the basis of surface hydration, ion hydration, and osmotic hydration of clay minerals. The higher the clay mineral content, the more likely that hydration will occur, resulting in more serious shale structure damage and a shorter time for damage to occur.

Lipase ZC12, a cold-adapted lipase derived from Psychrobacter sp. ZY124, can be effectively activated by Ca2+. Inspired by this significant property, we developed a novel immobilized lipase ZC12/Ca3(PO4)2 hybrid nanoflowers (LHNs). The LHNs have been characterized as a regular hierarchical flowerlike structure nanoflowers by scanning electron microscopy (SEM). Compared with free lipase ZC12, the LHNs exerted enhanced enzymatic activity of 206% and 2.31-fold in kcat/Km value, especially high specific activity at low temperature. After 7 successive cycles, the LHNs could still maintain its initial activity, demonstrating superior durability than the free lipase ZC12. Meanwhile, its stability basically kept unchanged in a wide range of temperature and pH. Finally, fructose laurate was transformed by the LHNs with 57.39% conversion rate which is twice as much as the free lipase. To sum up, these results validated that LHNs could emerge as an efficient immobilized lipase and possess the promising potential for practical applications.

Cyclic GMP-dependent protein kinase I (PKGI) mediates vascular relaxation by nitric oxide and related nitrovasodilators and inhibits vascular smooth muscle cell (VSMC) migration. To identify VSMC proteins that interact with PKGI, the N-terminal protein interaction domain of PKGIalpha was used to screen a yeast two-hybrid human aortic cDNA library. The formin homology (FH) domain-containing protein, FHOD1, was found to interact with PKGIalpha in this screen. FH domain-containing proteins bind Rho-family GTPases and regulate actin cytoskeletal dynamics, cell migration, and gene expression. Antisera to FHOD1 were raised and used to characterize FHOD1 expression and distribution in vascular cells. FHOD1 is highly expressed in human coronary artery, aortic smooth muscle cells, and in human arterial and venous endothelial cells. In glutathione S-transferase pull-down experiments, the FHOD1 C terminus (amino acids 964-1165) binds full-length PKGI. Both in vitro and intact cell studies demonstrate that the interaction between FHOD1 and PKGI is decreased 3- to 5-fold in the presence of the PKG activator, 8Br-cGMP. Immunofluorescence studies of human VSMC show that FHOD1 is cytoplasmic and is concentrated in the perinuclear region. PKGI also directly phosphorylates FHOD1, and studies with wild-type and mutant FHOD1-derived peptides identify Ser-1131 in the FHOD1 C terminus as the unique PKGI phosphorylation site in FHOD1. These studies demonstrate that FHOD1 is a PKGI-interacting protein and substrate in VSMCs and show that cyclic GMP negatively regulates the FHOD1-PKGI interaction. Based on the known functions of FHOD1, the data are consistent with a role for FHOD1 in cyclic GMP-dependent inhibition of VSMC stress fiber formation and/or migration.

To examine whether nitric oxide (NO) has a protective effect against Ca2+ overdose or a beneficial action on myocardial cells, we employed direct gene-transfer of endothelial (type III) nitric oxide synthase (eNOS), using HVJ (Sendai virus) coated liposomes and beta-galactosidase (lac-z) as a marker for the transfection. The transfection efficiency of the lac-z gene was comparable with adenovirus as a vector, though the subsequent inflammation was much improved. The lac-z gene transfection was restricted to myoplasm between two intercalated discs, indicating that the transfected gene dose not permeate the disc. Co-transfection with human eNOS gene revealed degraded myoplasm of not only transfected cells but adjacent myocytes, fibrotic changes and infiltration of mononuclear cells seven days after the transfection. Electron microscopy of the lesions revealed a huge accumulation of mitochondria and loss of myofilaments, though fragmentation of nucleus or cytoplasm was not obvious. We conclude that an expression of human eNOS gene in cardiomyocytes causes a degenerative process, incompatible with typical apoptosis.

In this article we describe three patients in whom biplane transesophageal echocardiography was useful in diagnosing sinus venosus type atrial septal defects. In two patients, diagnosis of anomalous pulmonary venous drainage was made correctly by biplane transesophageal echocardiography.

Ischemic process rarely involves the LA. To test the hypothesis that LA booster pump function is impaired in idiopathic dilated cardiomyopathy (DCM) but not in ischemic cardiomyopathy (ICM), peak Doppler mitral flow velocities in early diastole (E) and in atrial systole (A), and other indexes were measured within 24 hours of cardiac catheterization in 48 patients with ICM and 42 with DCM. Patients were divided into subgroups with normal (l12 mmHg) and high (≥12 mmHg) LV end-diastolic pressure (LVEDP). normal LVEDP high LVEDP ICM DCM ICM DCM n 21 17 27 25 LVEDP (mmHg) 8.7 ± 3.2 ns 8.2 ± 3.5 226 ± 5.1 ns 19.8 ± 7.2 LV % fraction shortening 20 ± 5 ns 18 ± 7 16 ± 5 ns 16 ± 6 Ecorrected by age (%) 101 ± 41 ns 96 ± 34 106 ± 53 ns 94 ± 40 Acorrected by age (%) 112 ± 45 ns 111 ± 51 103 ± 47 * 70 ± 36 A/E corrected by age (%) 124 ± 46 ns 106 ± 58 102 ± 45 * 67 ± 49 Atrial filling fraction (%) 39 ± 13 ns 35 ± 11 33 ± 13 * 21 ± 12 LV + dp/dt in atrial systole 137 ± 89 ns 128 ± 73 260 ± 92 * 217 ± 94 * p l 0.05, significant difference between ICM and DCM by ANOVA Only in high LVEDP groups, reverse pulmonary venous flow velocity in atrial systole measured by transesophageal echo was higher in ICM than in DCM (20 ± 4 vs 15 ± 4 cm/s). Autopsy showed severely fibrotic LA myocardium in 1 patient with DCM but not in 4 with ICM. Thus, LA booster pump function is not enough to fill LV in atrial systole in severe DCM with high LVEDP presumably because of involvement of LA with cardiomyopathic process.