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1.
Amber L. Hendricks Christine Wachnowsky Brian Fries Insiya Fidai James A. Cowan 《International journal of molecular sciences》2021,22(4)
Lipoyl synthase (LIAS) is an iron–sulfur cluster protein and a member of the radical S-adenosylmethionine (SAM) superfamily that catalyzes the final step of lipoic acid biosynthesis. The enzyme contains two [4Fe–4S] centers (reducing and auxiliary clusters) that promote radical formation and sulfur transfer, respectively. Most information concerning LIAS and its mechanism has been determined from prokaryotic enzymes. Herein, we detail the expression, isolation, and characterization of human LIAS, its reactivity, and evaluation of natural iron–sulfur (Fe–S) cluster reconstitution mechanisms. Cluster donation by a number of possible cluster donor proteins and heterodimeric complexes has been evaluated. [2Fe–2S]-cluster-bound forms of human ISCU and ISCA2 were found capable of reconstituting human LIAS, such that complete product turnover was enabled for LIAS, as monitored via a liquid chromatography–mass spectrometry (LC–MS) assay. Electron paramagnetic resonance (EPR) studies of native LIAS and substituted derivatives that lacked the ability to bind one or the other of LIAS’s two [4Fe–4S] clusters revealed a likely order of cluster addition, with the auxiliary cluster preceding the reducing [4Fe–4S] center. These results detail the trafficking of Fe–S clusters in human cells and highlight differences with respect to bacterial LIAS analogs. Likely in vivo Fe–S cluster donors to LIAS are identified, with possible connections to human disease states, and a mechanistic ordering of [4Fe–4S] cluster reconstitution is evident. 相似文献
2.
3.
Derrick K. Rollins Nidhi Bhandari Jim Kleinedler Kaylee Kotz Amber Strohbehn Lindsay Boland Megan Murphy Dave Andre Nisarg Vyas Greg Welk Warren E. Franke 《Journal of Process Control》2010,20(1):95-107
The goal of this work is to present a causation modeling methodology with the ability to accurately infer blood glucose levels using a large set of highly correlated noninvasive input variables over an extended period of time. These models can provide insight to improve glucose monitoring, and glucose regulation through advanced model-based control technologies. The efficacy of this approach is demonstrated using real data from a type 2 diabetic (T2D) subject collected under free-living conditions over a period of 25 consecutive days. The model was identified and tested using eleven variables that included three food variables as well as several activity and stress variables. The model was trained using 20 days of data and validated using 5 days of data. This gave a fitted correlation coefficient of 0.70 and an average absolute error (AAE) (i.e., the average of the absolute values for the measured glucose concentration minus modeled glucose concentration) of 13.3 mg/dL for the validation data. This AAE result was significantly better than the subject’s personal glucose meter AAE of 15.3 mg/dL for replicated measurements. 相似文献
4.
Amber L.Williams Jessica E.Fitzgerald Fernando Ivich Eduardo D.Sontag Mark Niedre 《光:科学与应用(英文版)》2021,(10):1998-1999
Dear Editor,
Circulating tumor cells (CTCs) are instrumental in hematogenous metastasis and are widely studied using liquid biopsy methods. 相似文献
5.
Streets SS Henderson SA Stoner AD Carlson DL Simcik MF Swackhamer DL 《Environmental science & technology》2006,40(23):7263-7269
Water from Lake Michigan and fish from all five Great Lakes have been sampled and analyzed for a suite of six polybrominated diphenyl ether (PBDE) congeners and 110 polychlorinated biphenyl congeners (PCBs). The Lake Michigan dissolved phase PBDE congener concentrations (0.2 to 10 pg/L) are similar to dissolved phase PCB congener concentrations (nondetected to 13 pg/L). Partitioning of PBDEs between the particulate and dissolved phases exhibits behavior similar to that of PCBs. Organic-carbon-normalized water-particle partition coefficients (log K(OC)s) ranged from 6.2 to 6.5. Lake trout are depleted in BDE-99 relative to dissolved phase concentrations, and in contrast to what is expected from the PCB congener patterns. This reflects suspected debromination of BDE-99 in the food web of Lake Michigan. A regression of the log of the bioaccumulation factor (BAF) and the log of the octanol-water partition coefficent (K(OW)) indicated a positive relationship for both PCB congeners and PBDE congeners. BDE-99 does not appear to followthe same trend, a further indication that it is subject to biotransformation. Using the PBDE BAFs for Lake Michigan and the PBDE fish concentrations from the other Great Lakes it is expected that the dissolved phase concentrations of congeners in the other lakes would range from 0.04 to approximately 3 pg/L. 相似文献
6.
Amber J. W. McClung Gyaneshwar P. Tandon Jeffery W. Baur 《Mechanics of Time-Dependent Materials》2012,16(2):205-221
In this study, the inelastic deformation behavior of an epoxy-based, thermally triggered shape memory polymer resin, known
as Veriflex-E, was investigated. The experimental program was designed to explore the influence of strain rate on monotonic
loading at various temperatures which is needed to establish the design space of SMPs in load bearing applications. Thermally
actuated shape memory polymers can be thought of as having two phases separated by the glass transition temperature (T
g
). At temperatures below the T
g
, Veriflex-E exhibits a high elastic modulus and positive, non-linear strain rate sensitivity in monotonic loading. The Poisson’s
ratio at room temperature is independent of the strain rate, but dependent upon the strain magnitude. As the temperature is
increased, the strain rate sensitivity in monotonic loading decreases. Well above the T
g
, the elastic modulus drops by several orders of magnitude. In this high temperature region, the material achieves strain
levels well above 100% and Poisson’s ratio is constant at 0.5 regardless of strain rate or strain magnitude. 相似文献
7.
Kai Yu Amber J. W. McClung Gyaneshwar P. Tandon Jeffrey W. Baur H. Jerry Qi 《Mechanics of Time-Dependent Materials》2014,18(2):453-474
This paper presents a three-dimensional (3D) finite deformation thermomechanical model to study the glass transition and shape memory behaviors of an epoxy based shape memory polymer (SMP) (Veriflex E) and a systematic material parameter identification scheme from a set of experiments. The model was described by viscoelastic elements placed in parallel to represent different active relaxation mechanisms around glass transition temperature in the polymer. A set of standard material tests was proposed and conducted to identify the model parameter values, which consequently enable the model to reproduce the experimentally observed shape memory (SM) behaviors. The parameter identification procedure proposed in this paper can be used as an effective tool to assist the construction and application of such 3D multi-branch model for general SMP materials. 相似文献
8.
Oxidation Behavior of Aerospace Materials in High Enthalpy Flows Using an Oxyacetylene Torch Facility 下载免费PDF全文
Melia Miller‐Oana Paul Neff Mario Valdez Amber Powell Matthew Packard Luke S. Walker Erica L. Corral 《Journal of the American Ceramic Society》2015,98(4):1300-1307
The oxyacetylene torch facility is used to measure the ablation rates of graphite and the surface temperatures of different aerospace materials. The free‐stream flame environment is characterized as a function of flame chemistry for heat flux, pO2, and flow velocity. Measured ablation rates for graphite increase as a function of increasing heat flux and pO2, which are validated by applying an oxygen diffusion based model. The model uses experimentally measured values for temperature, pO2, and gas velocity in order to confirm torch testing results are reliable and reproducible. Surface temperatures of ultra‐high temperature ceramic composites are measured as a function of increasing heat flux and show an enthalpic cooling effect on the flame during oxidation testing. 相似文献
9.
A Thieno[3,2‐b][1]benzothiophene Isoindigo Building Block for Additive‐ and Annealing‐Free High‐Performance Polymer Solar Cells 下载免费PDF全文
10.
Natural disasters greatly impact the environment of affected societies with often unknown consequences. In this study we examine the impact that the Canterbury Earthquakes of 2010–2011 had on the distribution of alcohol outlets in Christchurch, New Zealand. Specifically, we compare the distribution of both on-site and off-site alcohol outlets pre- (December 2009) and post-earthquake (December 2014) and use spatial regression models to identify whether any neighbourhood-level factors predict the observed redistributions. Overall, the number of alcohol outlets decreased by almost 13% after the Canterbury Earthquakes. However, we found a moderate increase in the clustering of both outlet types of outlets in the post-quake period. Increases in rates of both on-site and off-site alcohol outlets in neighbourhoods were positively associated with the percentage of residents who resided in their neighbourhood < 5 years and with neighbourhood crime rate change, while negative associations were found with percentage population aged between 15 and 29 years. The results suggest that the changing spatial distribution of alcohol outlets in Christchurch was not random but driven, in part, by the emergent demographic composition of neighbourhoods. The significant practical and policy implications of a redistribution of alcohol outlets are outlined providing a tangible link between empirical research and practice in an urban environment plagued with post-disaster spatial and social uncertainties. 相似文献