Fourier Analysis

傅里叶分析
  • 文章类型: Journal Article
    本实验和模型研究的目的是研究pH的影响,并确定表面覆盖率加上吸附在TiO2锐钛矿表面的牛血清白蛋白(BSA)蛋白的吸附常数(Ka),分别。在流通池中使用原位傅里叶变换红外衰减全反射光谱来研究BSA在多孔TiO2锐钛矿膜上的吸附。实验是在水溶液中进行的,在不同的pH值,浓度为10-6mol/l。理论上,我们扩展了两状态模型,基于耦合微分方程组,对于展开状态,通过添加解吸参数Kd2。考虑吸附(Ka),对模型进行了求解,解吸(Kd1,2),变换(Kf)系数,和初始溶液蛋白质浓度(C0)。研究结果清楚地表明,溶液的pH急剧改变了BSA的吸附行为,而数学解析解允许我们确定自然状态(θ1),展开状态(θ2),和完整的一个(θ)表面覆盖。最后,近似模型在实验工作中的良好应用,在pH=1.7时,吸附在TiO2锐钛矿上的膨胀BSA的值为Ka=(408.36±0.996)×102mol-1lmin-1。
    The purpose of this experimental and modeling research is to study the pH effect and to determine the surface coverage plus the adsorption constant (Ka) of bovine serum albumin (BSA) protein adsorbed on TiO2 anatase surface, respectively. In situ Fourier transform infrared-attenuated total reflection spectroscopy in a flow-through cell was used to study the BSA adsorption on porous TiO2 anatase films. The experiments were performed in water solution, under different pH values, at a concentration of 10-6 mol/l. Theoretically, we extended the two-state model, based on a system of coupled differential equations, by adding a desorption parameter Kd2, for unfolded state. The model was solved taking into account the adsorption (Ka), desorption (Kd1,2), transformation (Kf) coefficients, and the initial solution protein concentration (C0). The findings clearly illustrated that the solution pH drastically changed the behavior of BSA adsorption, whereas the mathematical analytical solutions allowed us to determine the native state (θ1), the unfolded state (θ2), and the full one (θ) surface coverages. Finally, a good application of the approximated model on the experimental work, expanded BSA adsorbed on TiO2 anatase at pH = 1.7, indicated a value of Ka = (408.36 ± 0.996) × 102 mol-1 l min-1.
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  • 文章类型: Journal Article
    Carbonized traditional Chinese medicine (TCM) is a kind of distinctive traditional drug which has been widely used in various bleeding syndromes for over two thousand years, and most of them are still in clinical use. Although they share similar processing method: stir-frying, there are no specific quality standards and few quality control researches carried out on carbonized TCM up until now. Carbonized Typhae Pollen (CTP) is a typical carbonized TCM with efficacy of eliminating blood stasis and stanching bleeding. In this study, a novel process quality control model coupled with near infrared spectroscopy was established, called Gradient-based Discriminant Analysis method (GDA). Compared with conventional modeling methods (Convolutional Neural Network, Linear Discriminant Analysis, Standard Normal Variate-LDA), GDA model applied in fiber optic probe acquisition mode exhibited highest test accuracy (0.961), satisfactory correct identification (internal validation, 100%; external validation, 97.1%) and excellent model stability. This method provided a perfect guideline for process quality control of Carbonized TCM as well as ensured their clinical efficacy.
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  • 文章类型: Journal Article
    Dynamic cerebral autoregulation and cerebral perfusion pressure are altered in pregnancies complicated by preeclampsia compared with normotensive pregnancies, but the connections of dynamic cerebral autoregulation, cerebral perfusion pressure, and cerebral complications in preeclampsia remain unclear.
    This study aimed to assess dynamic cerebral autoregulation and cerebral perfusion pressure after delivery in women with eclampsia, in women with preeclampsia both with and without severe features, and in normotensive women.
    This was a prospective case control study at a large referral hospital in Cape Town, South Africa. The recruitment of participants was done at diagnosis (cases) or at admission for delivery (controls). Transcranial Doppler examinations with continuous noninvasive blood pressure measurements and end-tidal CO2 monitoring were conducted for cases and controls after delivery. Cerebral perfusion pressure and dynamic cerebral autoregulation index were calculated, and values were compared among groups.
    We included 16 women with eclampsia, 18 women with preeclampsia with severe features, 32 women with preeclampsia without severe features, and 21 normotensive women with uncomplicated pregnancies. Dynamic cerebral autoregulation was depressed in pregnant women with eclampsia; (autoregulation index, 3.9; interquartile range, 3.1-5.2) compared with all other groups (those with preeclampsia with severe features, autoregulation index, 5.6 [interquartile range, 4.4-6.8]; those with preeclampsia without severe features, autoregulation index, 6.8 [interquartile range, 5.1-7.4]; and normotensive controls, autoregulation index, 7.1 [interquartile range, 6.1-7.9]). Pregnant women with eclampsia had increased cerebral perfusion pressure (109.5 mm Hg; interquartile range, 91.2-130.9) compared with those with preeclampsia without severe features and those with normal blood pressure (84 mm Hg [interquartile range, 73.0-122.0] and 80.0 mm Hg [interquartile range, 67.5-92.0], respectively); furthermore, there was no difference in cerebral perfusion pressure between pregnant women with eclampsia and pregnant women with preeclampsia with severe features (109.5 mm Hg [interquartile range, 91.2-130.9] vs 96.5 mm Hg [interquartile range, 75.8-110.5]).
    Cerebral perfusion pressure and dynamic cerebral autoregulation are altered in eclampsia and may be important in the pathophysiological pathway and constitute a therapeutic target in the prevention of cerebral complications in preeclampsia.
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  • 文章类型: Journal Article
    This article presents possible applications of a dynamic gravity meter (MGS-6, Micro-g LaCoste) for determining the dynamic height along the Odra River, in northwest Poland. The gravity measurement campaign described in this article was conducted on a small, hybrid-powered survey vessel (overall length: 9.5 m). We discuss a method for processing the results of gravimetric measurements performed on a mobile platform affected by strong external disturbances. Because measurement noise in most cases consists of signals caused by non-ideal observation conditions, careful attempts were made to analyze and eliminate the noise. Two different data processing strategies were implemented, one for a 20 Hz gravity data stream and another for a 1 Hz data stream. A comparison of the achieved results is presented. A height reference level, consistent for the entire estuary, is critical for the construction of a safe waterway system, including 3D navigation with the dynamic estimation of under-keel clearance on the Odra and other Polish rivers. The campaign was conducted in an area where the accuracy of measurements (levelling and gravimetric) is of key importance for shipping safety. The shores in the presented area of interest are swampy, so watercraft-based measurements are preferred. The method described in the article can be successfully applied to measurements in all near-zero-depth areas.
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  • 文章类型: Journal Article
    Olive pomace, a wet semi-solid paste that remains after olive oil extraction, is a major waste of the process and its recovery is mandatory due to its phytotoxicity when rejected directly into the soil. Innovative applications have been studied, but simple and reliable methods that fulfil the gap between the recovery of compounds and their use by industries (contributing to the sustainability and circular economy of the chain) still need to be explored. In this work, four monocultivar olive pomaces (Arbequina, Arbosana, Oliana, and Koroneiki) were studied regarding their nutritional composition, fatty acids and vitamin E profiles, total phenolic and flavonoid contents, antioxidant activity, and Fourier Transform Near Infrared and Mid Infrared spectra. Principal Component Analysis and Partial Least Square Discriminant Analysis were used to discriminate samples. Arbosana pomace presented the highest total fat (15%, dw) and vitamin E contents (1.4 mg/g of oil), being α-tocopherol the main vitamer in all samples. Koroneiki pomace was the richest in phenolic compounds (9 g gallic acid eq./kg). The major fatty acid was oleic acid. Stearic acid, linoleic acid, and FRAP levels differed significantly among cultivars. NIR spectra showed differences in all spectral regions (best separation from 6504 to 5389 cm-1 and 4961 to 4035 cm-1), while MIR spectra presented differences only in some spectral regions. The results showed that Near Infrared spectroscopy together with Principal Component Analysis is a powerful tool to discriminate olive pomace cultivars, with ability to be used in an industrial context.
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  • 文章类型: Journal Article
    In this study, an adjustment of the vocal tract shape toward selected sound waves in the frequency range of the first and second formants without phonation is discussed. The sound waves of a loudspeaker in front of the open mouth and amplified by the vocal tract are used as biofeedback signals. It is shown that the resonance amplification of the vocal tract complies with the concept of forced oscillation, with the driver being the sound source and the resonator being the vocal tract. An adjustment toward increased amplification via vocal tract resonance can be related to smaller bandwidths and lower damping. Furthermore, the applied adjustment frequencies are preserved as vocal tract resonances during exhalation and even phonation. This novel form of biofeedback might enrich standard voice training procedures by exercises without phonation.
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  • 文章类型: Journal Article
    基于快速傅里叶变换(FFT)的方法已成功应用于相对刚性的蛋白质-蛋白质复合物的建模。最近,我们已经能够使FFT方法适应柔性蛋白质-肽相互作用的治疗。这里,我们报告了我们的最新尝试,即在D3RPL-2016-1挑战中扩展FFT方法治疗柔性蛋白-配体相互作用的能力.根据D3R评估,我们的FFT方法结合蒙特卡罗最小化离网细化是挑战中表现最好的方法之一。我们方法的潜在优势是它能够在全球范围内对蛋白质-配体相互作用进行采样,这将在进一步的应用中进行探索。
    Fast Fourier transform (FFT) based approaches have been successful in application to modeling of relatively rigid protein-protein complexes. Recently, we have been able to adapt the FFT methodology to treatment of flexible protein-peptide interactions. Here, we report our latest attempt to expand the capabilities of the FFT approach to treatment of flexible protein-ligand interactions in application to the D3R PL-2016-1 challenge. Based on the D3R assessment, our FFT approach in conjunction with Monte Carlo minimization off-grid refinement was among the top performing methods in the challenge. The potential advantage of our method is its ability to globally sample the protein-ligand interaction landscape, which will be explored in further applications.
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  • 文章类型: Journal Article
    电生理研究已经分离了各种大脑区域中决策形成的神经特征。对啮齿动物和猴子的研究主要集中在效应子选择信号上,这些信号将新兴的决定转化为特定的运动计划。但是,最近,对人脑的研究已经确定了证据积累的抽象特征,该证据在行动准备中似乎没有任何直接作用。这些不同信号类型之间的功能解离才开始被表征,以及它们在决策过程中的动态,在有或没有预先了解刺激-效应子映射的情况下,在单单元和功能成像调查中通常研究的任务场景,尚未建立。在这里,我们以宽带中心顶叶阳性(CPP)和肢体选择性β波段(8-16和18-30Hz)的形式追踪了不同的抽象和效应器选择性决策信号的动力学EEG活动,分别,在延迟报告的运动方向决定期间,有和没有方向响应映射的预知。有了预知,在证据开始后,CPP和β波段信号表现出类似的逐渐积累,但是选择预测β带活性一直持续到延迟反应,CPP在达到峰值后向基线下降。没有预知,CPP表现出相同的动力学,而选择选择性β带活性被消除。这些发现强调了效应器选择性和抽象决策信号之间的定性功能区别,并且与建立决策功能神经影像学研究的假设相关。
    证据积累的神经特征已经在许多大脑区域被分离。尽管动物神经生理学主要集中在效应子选择决策信号上,这些信号将新兴的决策转化为特定的运动计划,最近对人脑的研究已经分离出决策形成的抽象神经特征,这些特征独立于特定的感觉和运动要求。这里,我们研究了在有和没有预先了解刺激-效应子映射的情况下,在具有延迟动作的决策过程中,两类不同的决策变量信号之间的功能差异。我们发现人脑中抽象决策信号与效应器选择性决策信号的动力学存在显着差异,在通过响应延迟和应急措施来维持刺激-响应映射的预知方面。
    Electrophysiological research has isolated neural signatures of decision formation in a variety of brain regions. Studies in rodents and monkeys have focused primarily on effector-selective signals that translate the emerging decision into a specific motor plan, but, more recently, research on the human brain has identified an abstract signature of evidence accumulation that does not appear to play any direct role in action preparation. The functional dissociations between these distinct signal types have only begun to be characterized, and their dynamics during decisions with deferred actions with or without foreknowledge of stimulus-effector mapping, a commonly studied task scenario in single-unit and functional imaging investigations, have not been established. Here we traced the dynamics of distinct abstract and effector-selective decision signals in the form of the broad-band centro-parietal positivity (CPP) and limb-selective β-band (8-16 and 18-30 Hz) EEG activity, respectively, during delayed-reported motion direction decisions with and without foreknowledge of direction-response mapping. With foreknowledge, the CPP and β-band signals exhibited a similar gradual build-up following evidence onset, but whereas choice-predictive β-band activity persisted up until the delayed response, the CPP dropped toward baseline after peaking. Without foreknowledge, the CPP exhibited identical dynamics, whereas choice-selective β-band activity was eliminated. These findings highlight qualitative functional distinctions between effector-selective and abstract decision signals and are of relevance to the assumptions founding functional neuroimaging investigations of decision-making.
    Neural signatures of evidence accumulation have been isolated in numerous brain regions. Although animal neurophysiology has largely concentrated on effector-selective decision signals that translate the emerging decision into a specific motor plan, recent research on the human brain has isolated abstract neural signatures of decision formation that are independent of specific sensory and motor requirements. Here, we examine the functional distinctions between the two distinct classes of decision variable signal during decisions with deferred actions with and without foreknowledge of stimulus-effector mapping. We find salient distinctions in the dynamics of abstract versus effector-selective decision signals in the human brain, in terms of sustainment through response delays and contingency on foreknowledge of stimulus-response mapping.
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  • 文章类型: Journal Article
    来自淋病奈瑟菌的NorM(NorM-NG)属于膜转运蛋白的多药和毒性化合物挤出(MATE)家族,它可以在细胞膜上挤出细胞毒性化学物质并赋予多药耐药性。这里,描述了NorM-NG的结构确定,这受到低分辨率(4)的阻碍,数据各向异性和伪摩罗面体孪生。使用分子置换解决了晶体结构,并通过进行差分傅立叶分析来证实。NorM-NG结构显示面向细胞外的构象,类似于与结晶伴侣结合的NorM-NG。讨论了确定NorM-NG结构的方法以及从本研究中吸取的教训,这对于分析具有类似缺点的X射线衍射数据可能是有用的。
    NorM from Neisseria gonorrhoeae (NorM-NG) belongs to the multidrug and toxic compound extrusion (MATE) family of membrane-transport proteins, which can extrude cytotoxic chemicals across cell membranes and confer multidrug resistance. Here, the structure determination of NorM-NG is described, which had been hampered by low resolution (∼ 4 Å), data anisotropy and pseudo-merohedral twinning. The crystal structure was solved using molecular replacement and was corroborated by conducting a difference Fourier analysis. The NorM-NG structure displays an extracellular-facing conformation, similar to that of NorM-NG bound to a crystallization chaperone. The approaches taken to determine the NorM-NG structure and the lessons learned from this study are discussed, which may be useful for analyzing X-ray diffraction data with similar shortcomings.
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  • 文章类型: Journal Article
    In metabolomics there is an ever-growing need for faster and more comprehensive analysis methods to cope with the increasing size of biological studies. Direct-infusion ion-cyclotron-resonance Fourier-transform spectrometry (DI-ICR-FT-MS) is used in non-targeted metabolomics to obtain high-resolution snapshots of the metabolic state of a system. We applied this technology to a Caenorhabditis elegans-Pseudomonas aeruginosa infection model and optimized times needed for cultivation and mass-spectrometric analysis. Our results reveal that DI-ICR-FT-MS is a promising tool for high-throughput in-depth non-targeted metabolomics. We performed whole-worm metabolomics and recovered markers of the induced metabolic changes in C. elegans brought about by interaction with pathogens. In this investigation, we reveal complex metabolic phenotypes enabling clustering based upon challenge. Specifically, we observed a marked decrease in amino-acid metabolism with infection by P. aeruginosa and a marked increase in sugar metabolism with infection by Salmonella enterica. We were also able to discriminate between infection with a virulent wild-type Pseudomonas and with an attenuated mutant, making it possible to use this method in larger genetic screens to identify host and pathogen effectors affecting the metabolic phenotype of infection.
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