The re-discovery of the fast Fourier transform algorithm

The discovery of the fast Fourier transform (FFT) algorithm and the subsequent development of algorithmic and numerical methods based on it have had an enormous impact on the ability of computers to process digital representations of signals, or functions. At first, the FFT was regarded as entirely new. However, attention and wide publicity led to an unfolding of its pre-electronic computer history going back to Gauss. The present paper describes the author's own involvement and experience with the FFT algorithm.The author is grateful for permission from the Association for Computing Machinery to allow the present paper to bear some similarity with the paper,How the FFT Gained Acceptance, ref. [28]     

快速傅立叶变换用于色谱噪声平滑及微弱信号的检测

应用快速傅立叶变换法（ＦＦＴ）对色谱噪声进行平滑处理及微弱信号检测,同时,也与其他数字滤波法进行了比较。结果表明,利用ＦＦＴ法可以很好地对噪声进行平滑处理,使信噪比提高１８倍,为更好地进行痕量组分的色谱微弱信号检测打下了基础。     

Metal(II) complexes of bioactive aminonaphthoquinone-based ligand: synthesis,characterization and BSA binding,DNA binding/cleavage,and cytotoxicity studies

An aminonaphthoquinone ligand, L, and its metal complexes of general formula [MLCl₂] {M = Co(II), Ni(II), Cu(II) and Zn(II)} have been synthesized and characterized by analytical and spectral techniques. Tetrahedral geometry has been assigned to Ni(II) and Zn(II) complexes and square planar geometry to Co(II) and Cu(II) complexes on the basis of electronic spectral and magnetic susceptibility data. The binding of complexes with bovine serum albumin (BSA) is relatively stronger than that of free ligand and alters the conformation of the protein molecule. Interaction of these complexes with CT-DNA has been investigated using UV-Vis and fluorescence quenching experiments, which show that the complexes bind strongly to DNA through intercalative mode of binding (K_app 10⁵ M^?1). Molecular docking studies reiterate the mode of binding of these compounds with DNA, proposed by spectral studies. The ligand and its complexes cleave plasmid DNA pUC18 to nicked (Form II) and linear (Form III) forms in the presence of H₂O₂ oxidant. The in vitro cytotoxicity screening shows that Cu(II) complex is more potent against MCF-7 cells and Zn(II) complex exhibits marked cytotoxicity against A-549 cells equal to that of cisplatin. Cell imaging studies suggested apoptosis mode of cell death in these two chosen cell lines.     

Sotalol nanolevel detection at an Au microelectrode in flowing solutions

Sotalol detection in tablets is achieved with the help of a newly developed, time-saving, and simple method, called fast Fourier transform with continuous cyclic voltammetry (FFTCV). Noticeably, FFTCV illustrates two advantages, not being demonstrated by earlier reports. First, there is no requirement for the oxygen removal from the test solution. In addition, the speed of the method for determining any compound is high in a broad range of chromatographic methods. This research includes the observation of effects of various parameters (influence of the pH of the eluent, accumulation potential, sweep rate, accumulation time) on the sensitivity of the detection system. Finally, the technique was found to be linear for the concentration range of 3–14900 pg/ml (r = 0.998) with a limit of detection and quantitation of 0.95 pg/ml and 3 pg/ml, respectively. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 9, pp. 1103–1110. The text was submitted by the authors in English.     

Novel method for the determination of trace amounts of metformin in its pharmaceutical formulation by fast Fourier continuous cyclic voltametric technique at Au microelectrode in flowing solutions

An easy and fast Fourier transform continuous cyclic voltametric technique for monitoring of ultra trace amounts of metformin in a flow-injection system has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping and potential ramp, was continuously applied on an Au disk microelectrode (12.5 μm in radius). The proposed detection method has some of advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The detection limit for metformin was 43 pg/ml. The relative standard deviation (RSD) of the proposed technique at 5.0 × 10⁻⁷ M was 2.2% for 10 runs. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the metformin were considered. The proposed method was applied to the determination of metformin in a pharmaceutical preparation. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 10, pp. 1221–1230. The text was submitted by the authors in English.     

傅里叶变换用于快扫伏安法的电流分离

根据电化学池的电学模型,推导出相应的数学模型,和傅里变变换相结合,实现了扫描伏安数据的充电电流和法拉第电流的分离。模拟数据和实验数据的处理结果表明,所提出的方法均能实现充电电流和法拉第电流的分离,得到的结果与理论模型一致。     

Design of Ligand Binding to an Engineered Protein Cavity Using Virtual Screening and Thermal Up-shift Evaluation

Summary Proteins could be used to carry and deliver small compounds. As a tool for designing ligand binding sites in protein cores, a three-step virtual screening method is presented that has been optimised using existing data on T4 lysozyme complexes and tested in a newly engineered cavity in flavodoxin. The method can pinpoint, in large databases, ligands of specific protein cavities. In the first step, physico-chemical filters are used to screen the library and discard a majority of compounds. In the second step, a flexible, fast docking procedure is used to score and select a smaller number of compounds as potential binders. In the third step, a finer method is used to dock promising molecules of the hit list into the protein cavity, and an optimised free energy function allows discarding the few false positives by calculating the affinity of the modelled complexes. To demonstrate the portability of the method, several cavities have been designed and engineered in the flavodoxin from Anabaena PCC 7119, and the W66F/L44A double mutant has been selected as a suitable host protein. The NCI database has then been screened for potential binders, and the binding to the engineered cavity of five promising compounds and three tentative non-binders has been experimentally tested by thermal up-shift assays and spectroscopic titrations. The five tentative binders (some apolar and some polar), unlike the three tentative non-binders, are shown to bind to the host mutant and, importantly, not to bind to the wild type protein. The three-step virtual screening method developed can thus be used to identify ligands of buried protein cavities. We anticipate that the method could also be used, in a reverse manner, to identify natural or engineerable protein cavities for the hosting of ligands of interest.     

High Order Harmonic A.C Oscillographic Chronopotentiometry

Inrecentyears,oscillographictitrationhasbecomeanewareaofelectfotitrimetricanalysis.Yet,sincetherearesomeproblemsofreproducibility,sensitivityandresolvingpowerontheoscillogram,methodoftheoscillographicdeterminationformicroortracesubstancecannotbewellusedinactualanalysis..Inordertodevelopthemethod,theauthorshavestudiedthethreebasicproblems,exploredseveralnewoscillographicmethods,andimprovedsomeoldmethods.Asaresult,theoscillographicmethodhasexceededtherangeofthetitration,andhasgrowntobetheoscillo…