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171.
Summary. The global dynamics of flexible spinning discs are studied. The discs studied are parametrically excited in their spin rate,
and have imperfections that cause symmetry-breaking. After determining the equations of motion in a suitable form, the energy-phase
method is employed to show the existence of chaotic dynamics by identifying multipulse jumping orbits in the perturbed phase
space. We provide restrictions on the damping, forcing, and symmetry-breaking parameters in order for these complicated dynamics
to occur. The dissipative version of the energy-phase method predicts a wider range of values for which chaotic dynamics occurs
than the traditional Melnikov method. The results are then discussed in terms of the physical motion of the spinning disc
system. The multipulse orbits are manifested in the physical system as a shifting between two different nodal configurations
of the disc. When the motion is chaotic, an observer will see a random jumping between the two nodal configurations of the
disc.
Received February 7, 2000; accepted November 18, 2001 相似文献
172.
Renu Singh Zimple Matharu Avanish Kumar Srivastava Seema Sood Rajinder Kumar Gupta Bansi Dhar Malhotra 《Mikrochimica acta》2012,177(1-2):201-210
We report on a nanocomposite based genosensor for the detection of Neisseria gonorrhoeae, a bacterium causing the sexually transmitted disease gonorrhoea. Amino-labeled probe DNA was covalently immobilized on electrochemically prepared polyaniline and iron oxide (PANI-Fe3O4) nanocomposite film on an indium tin oxide (ITO) electrode. Scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) techniques have been employed to characterize surface of the modified electrode. The genosensor has detection limits of 1?×?10-15 M and 1?×?10-17 M, respectively, using the EIS and DPV techniques. This biosensor can discriminate a complementary sequence from a single-base mismatch and from non-complementary DNA, and has been utilized for detection of DNA extracted from N. gonorrhoeae culture, and from patient samples with N. gonorrhoeae. It is found to exhibit good specificity for N. gonorrhoeae species and shows no response towards non-gonorrhoeae type of Neisseria species (NgNs) and other gram-negative bacterias (GNBs). The affinity constant for hybridization calculated using the Langmuir adsorption isotherm model is found to be 3.39?×?108 M-1. Figure
Electrochemically deposited nanostructured platform for Neisseria gonorrhoeae detection. 相似文献
173.
Bernard S. Munge Colleen E. Krause Ruchika Malhotra Vyomesh Patel J. Silvio Gutkind James F. Rusling 《Electrochemistry communications》2009,11(5):1009-1012
Electrochemical immunosensors based on single wall nanotube (SWNT) forests and 5 nm glutathione-protected gold nanoparticles (GSH-AuNP) were developed and compared for the measurement of human cancer biomarker interleukin-6 (IL-6) in serum. Detection was based on sandwich immunoassays using multiple (14–16) horseradish peroxidase labels conjugated to a secondary antibody. Performance was optimized by effective blocking of non-specific binding (NSB) of the labels using bovine serum albumin. The GSH-AuNP immunosensor gave a detection limit (DL) of 10 pg mL?1 IL-6 (500 amol mL?1) in 10 μL calf serum, which was 3-fold better than 30 pg mL?1 found for the SWNT forest immunosensor for the same assay protocol. The GSH-AuNPs platform also gave a much larger linear dynamic range (20–4000 pg mL?1) than the SWNT system (40–150 pg mL?1), but the SWNTs had 2-fold better sensitivity in the low pg mL?1 range. 相似文献
174.
Zimple Matharu Pratibha Pandey M. K. Pandey Vinay Gupta B. D. Malhotra 《Electroanalysis》2009,21(14):1587-1596
Mediator free enzyme sensor has been fabricated by covalently immobilizing cholesterol oxidase (ChOx) onto 11‐mercaptoundecanoic acid functionalized gold nanoparticles (MUDA‐AuNPs) – octadecylamine (ODA) hybrid Langmuir–Blodgett film. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies reveal that MUDA‐AuNP/ODA LB film has good affinity for ChOx and provides favorable microenvironment for direct electron transfer between enzyme and electrode. Interference free estimation of cholesterol has been realized at 0.3 V with linear range from 25 to 500 mg/dL, detection limit of 23.38 mg/dL, sensitivity of 1.085 μA mM?1 and response time of 20 s at pH 7.0. 相似文献
175.
176.
We investigate the performance of the Super Dense Wavelength Division Multiplexed (SDWDM) systems with high spectral efficiency and narrow spacing of the channels and optimization in terms of bit rate up to 15 Gbps, channel spacing as low as 12.5 GHz, number of channels up to 64 and repeater less transmission distance up to 100 km and report high capacity SDWDM systems. We demonstrate the minimal allowed channel spacing and provide recommendations for future SDWDM solutions. The simulation results have shown that the minimum channel spacing for 15 Gbps, 32 channel system need to be not less than 0.35 nm and that for a 10 Gbps system it should be not less than 0.25 nm. The 5 Gbps system gives acceptable results at spacing of 0.1 nm for maximum up to single span of 80 km. 相似文献
177.
Jagjit Singh Malhotra 《Optik》2010,121(9):800-807
This paper presents the performance analysis of non-return-to-zero (NRZ), return-to-zero (RZ), chirped return-to-zero (CRZ) and carrier suppressed return-to-zero (CSRZ) data formats in optical soliton transmission link under the impact of chirp and third-order dispersion (TOD). The performance of these data formats has been analyzed on the basis of certain performance metrics, viz, bit error rate (BER), Q2 (dB), OSNR, eye opening, etc. It has been reported here that the performance of CRZ and CSRZ modulation format is better as compared to NRZ and RZ in a soliton transmission link. Further, CSRZ modulation format has been found to deliver optimum performance on the basis of performance evaluation metrics reported in this paper. In case of NRZ and CSRZ, comparatively narrow power spectrum has been observed. Best eye opening, highest value of Q2 (dB) of 18 dB and lowest value of BER of the order of 10−16 has been reported in case of CSRZ among the considered data formats. The results have been obtained by varying noise figure from 3.0 to 9.0. No considerable effect of noise was observed. It was observed that at very narrow and ultra short pulse width, OSNR value suffers heavily and reduced to even negative values in dB, thus inducing a high degree of OSNR power penalty. The results were obtained by varying chirp factor from −0.6 to +0.6. Negative chirp resulted in improved OSNR as compared to positive chirp. RZ data format yielded a broader optical spectrum, comparatively low spectral efficiency and poor OSNR thus it was found that RZ format is not suitable for optical soliton transmission under the impact of chirp and TOD. 相似文献
178.
Dissecting Ubiquitin Signaling with Linkage‐Defined and Protease Resistant Ubiquitin Chains 下载免费PDF全文
Tatjana Schneider Dr. Daniel Schneider Daniel Rösner Saurav Malhotra Franziska Mortensen Prof. Dr. Thomas U. Mayer Prof. Dr. Martin Scheffner Prof. Dr. Andreas Marx 《Angewandte Chemie (International ed. in English)》2014,53(47):12925-12929
Ubiquitylation is a complex posttranslational protein modification and deregulation of this pathway has been associated with different human disorders. Ubiquitylation comes in different flavors: Besides mono‐ubiquitylation, ubiquitin chains of various topologies are formed on substrate proteins. The fate of ubiquitylated proteins is determined by the linkage‐type of the attached ubiquitin chains, however, the underlying mechanism is poorly characterized. Herein, we describe a new method based on codon expansion and click‐chemistry‐based polymerization to generate linkage‐defined ubiquitin chains that are resistant to ubiquitin‐specific proteases and adopt native‐like functions. The potential of these artificial chains for analyzing ubiquitin signaling is demonstrated by linkage‐specific effects on cell‐cycle progression. 相似文献
179.
Estimation of impurities in reactor grade uranium is important from the point of view of neutron economy. For chemical separation, ion exchange and solvent extraction techniques have been employed although the latter is generally preferred. Amongst various extractants TBP (tri-n-butyl phosphate), TBP-TOPO (tri-n-octyl phosphine oxide), or TOPO only (in CCl(4), xylene, dodecane) is most often used. New reagents like Cyanex-923 (mixture of 4 tri-alkyl phosphine oxides)/TEHP (tri-ethylhexyl phosphoric acid) are also being used. This communication reports chemical separation of uranium by precipitation using 1,2-diaminocyclohexane NNN'N'-tetra acetic acid (CyDTA)/ammonium hydroxide in presence of 1,10-phenanthroline and estimation of impurities in the filtrate by ICP-AES. Quantitative separation of U, a high spectral interferent in plasma and recovery of impurities have been achieved. Recovery of Cd has been improved by using 1,10-phenanthroline. The method is accurate and precise, offering a relative standard deviation ranging from less than 4% (3.8% for Eu at the 10mug g(-1) level) to 12.9% (for Ce at the 2.5 mug g(-1) level) for all the elements studied. 相似文献
180.
Amit L. Sharma Manju Gerard Rahul Singhal B. D. Malhotra S. Annapoorni 《Applied biochemistry and biotechnology》2001,96(1-3):155-165
Poly(2-fluoroaniline) was prepared by both chemical and electrochemical polymerization in acidic medium. Characterization
of poly(2-fluoroaniline) was accomplished experimentally using ultraviolet-visible, Fourier transform infrared, differential
scanning calorimetry, thermal gravimetric analysis, and X-ray diffraction techniques, respectively. Scanning electron microscopy
studies revealed globular morphology of chemically synthesized poly(2-fluoroaniline). The cyclic voltammetric studies revealed
diffusion-controlled phenomenon in electrochemically synthesized poly(2-fluoroaniline). 相似文献