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排序方式: 共有50条查询结果,搜索用时 15 毫秒
1.
Heena Lamba Latha Sabikhi Dipesh Aggarwal Urmila Choudhary Srinu Reddi Suman Kapila Rajeev Kapila 《International Journal of Food Science & Technology》2018,53(3):626-633
Guggul tree or Commiphora mukul is a small thorny herb having remarkable hypocholesterolaemic properties. Its therapeutic effects are because of its biocomponent guggulsterones, especially guggulsterone E and Z. In this research, double emulsion‐based spread was tried to improve the bioavailability of the herb guggul in in vivo rat model. The effect of the different diets with encapsulated and nonencapsulated guggul was evaluated and compared after 6 weeks, based on the final body weight and analysis of organs, serum and faeces of normal and hypercholesterolaemic (H) rats. It was evident from the results that double emulsion‐encapsulated guggul showed better control on weight of H rats (25.98% lower), inhibition of HMG CoA reductase (3.95 times less) activity and reduction in atherosclerotic index (47.2%), as compared to diet with unencapsulated guggul. Encapsulation of guggul also improved faecal excretion of bile acids, lipids and total cholesterol in H and normal rats. 相似文献
2.
Photonic Network Communications - In this paper, a novel two dimensional (2D) wavelength/time (W/T) optical code division multiple access (OCDMA) code with zero cross-correlation property to... 相似文献
3.
Sven H. Rouschop Samantha J. Snow Urmila P. Kodavanti Marie-Jos Drittij Lou M. Maas Antoon Opperhuizen Frederik J. van Schooten Alexander H. Remels Roger W. Godschalk 《International journal of molecular sciences》2021,22(14)
Previous research has shown that a perinatal obesogenic, high-fat diet (HFD) is able to exacerbate ozone-induced adverse effects on lung function, injury, and inflammation in offspring, and it has been suggested that mitochondrial dysfunction is implicated herein. The aim of this study was to investigate whether a perinatal obesogenic HFD affects ozone-induced changes in offspring pulmonary oxidant status and the molecular control of mitochondrial function. For this purpose, female Long-Evans rats were fed a control diet or HFD before and during gestation, and during lactation, after which the offspring were acutely exposed to filtered air or ozone at a young-adult age (forty days). Directly following this exposure, the offspring lungs were examined for markers related to oxidative stress; oxidative phosphorylation; and mitochondrial fusion, fission, biogenesis, and mitophagy. Acute ozone exposure significantly increased pulmonary oxidant status and upregulated the molecular machinery that controls receptor-mediated mitophagy. In female offspring, a perinatal HFD exacerbated these responses, whereas in male offspring, responses were similar for both diet groups. The expression of the genes and proteins involved in oxidative phosphorylation and mitochondrial biogenesis, fusion, and fission was not affected by ozone exposure or perinatal HFD. These findings suggest that a perinatal HFD influences ozone-induced responses on pulmonary oxidant status and the molecular control of mitophagy in female rat offspring. 相似文献
4.
Umakanta Swain Gilgi Friedlander Urmila Sehrawat Avital Sarusi-Portuguez Ron Rotkopf Charlotte Ebert Tamar Paz-Elizur Rivka Dikstein Thomas Carell Nicholas E. Geacintov Zvi Livneh 《International journal of molecular sciences》2021,22(13)
TENT4A (PAPD7) is a non-canonical poly(A) polymerase, of which little is known. Here, we show that TENT4A regulates multiple biological pathways and focuses on its multilayer regulation of translesion DNA synthesis (TLS), in which error-prone DNA polymerases bypass unrepaired DNA lesions. We show that TENT4A regulates mRNA stability and/or translation of DNA polymerase η and RAD18 E3 ligase, which guides the polymerase to replication stalling sites and monoubiquitinates PCNA, thereby enabling recruitment of error-prone DNA polymerases to damaged DNA sites. Remarkably, in addition to the effect on RAD18 mRNA stability via controlling its poly(A) tail, TENT4A indirectly regulates RAD18 via the tumor suppressor CYLD and via the long non-coding antisense RNA PAXIP1-AS2, which had no known function. Knocking down the expression of TENT4A or CYLD, or overexpression of PAXIP1-AS2 led each to reduced amounts of the RAD18 protein and DNA polymerase η, leading to reduced TLS, highlighting PAXIP1-AS2 as a new TLS regulator. Bioinformatics analysis revealed that TLS error-prone DNA polymerase genes and their TENT4A-related regulators are frequently mutated in endometrial cancer genomes, suggesting that TLS is dysregulated in this cancer. 相似文献
5.
Modeling of many dynamic systems results in matrix second-order differential equations. In the paper, the stability issues of matrix second-order dynamical systems are discussed. In the literature, only sufficient conditions of stability and/or instability for a system in matrix second-order form are available. In this paper, necessary and sufficient conditions of asymptotic stability for time-invariant systems in matrix second-order form under different types of dynamic loadings (conservative/nonconservative) are derived and a physical interpretation is carried out. The stability conditions in the sense of Lyapunov (the jw-axis behavior of eigenvalues) are also analyzed. As the conditions are gained directly in terms of physical parameters of the system, the effect of different loadings on the system stability is made transparent by dealing with the stability issues directly in matrix second-order form 相似文献
6.
Santosh Konangi Nikhil K. Palakurthi Urmila Ghia 《Computers & Mathematics with Applications》2018,75(2):643-665
In literature, the von Neumann stability analysis of simplified model equations, such as the wave equation, is typically used to determine stability conditions for the non-linear partial differential fluid flow equations (Navier–Stokes and Euler). However, practical experience suggests that such simplistic stability conditions are grossly inadequate for computations involving the system of coupled flow equations. The goal of this paper is to determine stability conditions for the full system of fluid flow equations – the Euler equations are examined, as any conditions derived for the Euler equations will apply to the Navier–Stokes (NS) equations in the limit of convection-dominated flows. A von Neumann stability analysis is conducted for the one-dimensional (1D) and two-dimensional (2D) Euler equations. The system of equations is discretized on a staggered grid using finite-difference discretization techniques; the use of a staggered grid allows equivalence to finite-volume discretization. By combining the different discretization techniques, ten solution schemes are formulated – eight solution schemes are considered for the 1D Euler equations, and two schemes for the 2D Euler equations. For each scheme, error amplification matrices are determined from the stability analysis, stable and unstable regimes are identified, and practical stability limits are predicted in terms of the maximum-allowable CFL (Courant–Friedrichs–Lewy) number as a function of Mach number. The predictions are verified for selected schemes using the Riemann problem at incompressible and compressible Mach numbers. Very good agreement is obtained between the analytically predicted and the “experimentally” observed CFL values. The successfully tested stability limits are presented in graphical form, which offer a viable alternative to complicated mathematical expressions often reported in published literature, and should benefit everyday CFD (Computational Fluid Dynamics) users. The stability regions are used to discuss the effect of time integration (explicit vs. implicit), density bias in continuity equation and momentum convection term linearization on stability. A comparison of the predicted stability limits for 1D and 2D Euler equations with commonly-used stability conditions arising from the wave equation shows that the stability thresholds for the Euler equations lie well below those predicted by the wave equation analysis; in addition, the 2D Euler stability limits are more restrictive as compared to 1D Euler limits. Since the present analysis accounts for the full system of fluid flow (Euler) equations, the derived stability conditions can be used by CFD practitioners to estimate a timestep or CFL number to guide the stability of their computations. 相似文献
7.
Coal-fired power plants are large water consumers. Water consumption in thermoelectric generation is strongly associated with evaporation losses and makeup streams on cooling and contaminant removal systems. Thus, minimization of water consumption requires optimal operating conditions and parameters, while fulfilling the environmental constraints. Several uncertainties affect the operation of the plants, and this work studies those associated with weather. Air conditions (temperature and humidity) were included as uncertain factors for pulverized coal (PC) power plants. Optimization under uncertainty for these large-scale complex processes with black-box models cannot be solved with conventional stochastic programming algorithms because of the large computational expense. Employment of the novel better optimization of nonlinear uncertain systems (BONUS) algorithm, dramatically decreased the computational requirements of the stochastic optimization. Operating conditions including reactor temperatures and pressures; reactant ratios and conditions; and steam flow rates and conditions were calculated to obtain the minimum water consumption under the above-mentioned uncertainties. Reductions of up to 6.3% in water consumption were obtained for the fall season when process variables were set to optimal values. Additionally, the proposed methodology allowed the analysis of other performance parameters like gas emissions and cycle efficiency which were also improved. 相似文献
8.
Nutrient monitoring is very important for the area of food–energy–water nexus. The sensor network for nutrient monitoring requires dynamic sensing where the positions of the sensors change with time. In this work, we have proposed a methodology to optimize a dynamic sensor network which can address the spatiotemporal aspect of nutrient movement in a watershed. This is a first paper in the series where an algorithmic and methodological framework for spatiotemporal sensor placement problem is proposed. Dynamic sensing is widely used in wireless sensors, and the current approaches to solving this problem are data intensive. This is the first time we are introducing a stochastic optimization approach to dynamic sensing which is efficient. This framework is based on a novel stochastic optimization algorithm called Better Optimization of Nonlinear Uncertain Systems (BONUS). A small case study of the dynamic sensor placement problem is presented to illustrate the approach. In the second paper of this series, we will present a detailed case study of nutrient monitoring in a watershed. 相似文献
9.
Y. Fu U. M. Diwekar D. Young H. Cabezas 《Clean Technologies and Environmental Policy》2000,2(2):92-107
Designing chemical processes for the environment requires consideration of several indexes of environmental impact including
ozone depletion, global warming potentials, human and aquatic toxicity, photochemical oxidation, and acid rain potentials.
Current methodologies, such as the generalized waste reduction algorithm (WAR), provide a first step towards evaluating these
impacts. However, to address the issues of accuracy and the relative weights of these impact indexes, one must consider the
problem of uncertainties. Environmental impacts must also be weighted and balanced against other concerns, such as their cost
and long-term sustainability. These multiple, often conflicting, goals pose a challenging and complex optimization problem,
requiring multi-objective optimization under uncertainty. This paper will address the problem of quantifying and analyzing
the various objectives involved in process design for the environment. Towards this goal, we proposed a novel multi-objective
optimization framework under uncertainty. This framework is based on new and efficient algorithms for multi-objective optimization
and for uncertainty analysis. This approach finds a set of potentially optimal designs where trade-offs can be explicitly
identified, unlike cost-benefit analysis, which deals with multiple objectives by identifying a single fundamental objective
and then converting all the other objectives into this single currency. A benchmark process for hydrodealkylation (HDA) of
toluene to produce benzene modeled in the ASPEN simulator is used to illustrate the usefulness of the approach in finding
environmentally friendly and cost-effective designs under uncertainty.
Received: 8 February 2000 / Accepted: 10 March 2000 相似文献
10.
Dominic L. Boccelli Mitchell J. Small Urmila M. Diwekar 《Canadian Metallurgical Quarterly》2007,133(3):303-312
Both inherent natural variability and model parameter uncertainty must be considered in the development of robust and reliable designs for drinking water treatment. This study presents an optimization framework for investigating the effects of five variable influent parameters and three uncertain model parameters on the least-cost treatment plant configuration (contact, direct, or nonsweep conventional filtration) that reliably satisfies an effluent particulate matter concentration constraint. Incorporating variability and uncertainty within the decision-making framework generates information for investigating: (1) impacts on total cost and treatment reliability; (2) shifts on the least-cost treatment configuration for providing reliable treatment; and (3) the importance of the individual variable and uncertain parameter distributions for reliably satisfying an effluent water quality constraint. Increasing the magnitude of influent variability and model parameter uncertainty results in a greater expected design cost due, generally, to increases in process sizing required to reliably satisfy the effluent concentration constraint. The inclusion of variability and uncertainty can also produce a shift in the locations of the least-cost configuration regions, which are dependent on the expected influent water quality and the magnitude of variability and uncertainty. The additional information provided by incorporating the variable and uncertain parameters illustrates that parameter distributions related to the primary removal mechanism are critical, and that contact and direct filtration are more sensitive to variability and uncertainty than conventional filtration. 相似文献