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91.
Parthasarathy M Singh S Hazra S Pillai VK 《Analytical and bioanalytical chemistry》2008,391(6):2227-2233
The stomatal physiology, chlorophyll distribution and photosynthetic activity of somatic embryo (SE)- and seedling-derived
peanut plants grown in vitro (test tube-grown) and extra vitrum (soil-grown) are investigated using scanning electrochemical microscopy (SECM). This SECM
imaging is performed in two different feedback modes, corresponding to oxygen evolution and chlorophyll distribution. More
specifically, the oxygen evolution profiles of the in vitro leaves indicate important differences in leaf anatomy between the SE- and seedling-derived leaves. On the other hand, the
chlorophyll distribution images show individual stomata of size ca. 27 ± 5μm. Further studies on senescing (aged) leaves reveal
interesting voltammograms that vary widely over the stomatal complexes and the surrounding tissues, probably due to the release
of electroactive metabolites during chlorophyll breakdown when the leaves turn yellow. Thus, the present investigation could
open up new opportunities for characterizing botanical systems using electroanalytical techniques. In addition, it could provide
further insights into various areas of current relevance, including signal transduction, cell fate/differentiation and developmental
biology.
Schematic representation of SECM imaging used in this investigation. The SECM probe is a Pt UME disk (25 μm diameter) embedded
in an insulating glass sheath so that the ratio of the diameter of the death to that of the electrode surface (RG) is 7. RE denotes the reference electrode Ag/AgCl, sat. KCl and CE refers to the counter electrode, a Pt wire. Oxygen evolving from the leaf surface during photosynthesis diffuses into the
electrolyte (0.1 M KCl) and gets reduced at the Pt UME, biased to a potential of −0.5 V, at a diffusion-limited rate to produce
a change in the tip-current 相似文献
92.
Meera Shete Manjesh Kumar Dr. Donghun Kim Neel Rangnekar Dandan Xu Prof. Berna Topuz Dr. Kumar Varoon Agrawal Evguenia Karapetrova Prof. Benjamin Stottrup Prof. Shaeel Al‐Thabaiti Prof. Sulaiman Basahel Dr. Katabathini Narasimharao Prof. Jeffrey D. Rimer Prof. Michael Tsapatsis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(2):550-554
Nanoscale crystal growth control is crucial for tailoring two‐dimensional (2D) zeolites (crystallites with thickness less than two unit cells) and thicker zeolite nanosheets for applications in separation membranes and as hierarchical catalysts. However, methods to control zeolite crystal growth with nanometer precision are still in their infancy. Herein, we report solution‐based growth conditions leading to anisotropic epitaxial growth of 2D zeolites with rates as low as few nanometers per day. Contributions from misoriented surface nucleation and rotational intergrowths are eliminated. Growth monitoring at the single‐unit‐cell level reveals novel nanoscale crystal‐growth phenomena associated with the lateral size and surface curvature of 2D zeolites. 相似文献
93.
Meera Mehta Dr. Michael H. Holthausen Ian Mallov Dr. Manuel Pérez Dr. Zheng‐Wang Qu Prof. Dr. Stefan Grimme Prof. Dr. Douglas W. Stephan 《Angewandte Chemie (International ed. in English)》2015,54(28):8250-8254
Ketones are efficiently deoxygenated in the presence of silane using highly electrophilic phosphonium cation (EPC) salts as catalysts, thus affording the corresponding alkane and siloxane. The influence of distinct substitution patterns on the catalytic effectiveness of several EPCs was evaluated. The deoxygenation mechanism was probed by DFT methods. 相似文献
94.
The free energy principle from neuroscience has recently gained traction as one of the most prominent brain theories that can emulate the brain’s perception and action in a bio-inspired manner. This renders the theory with the potential to hold the key for general artificial intelligence. Leveraging this potential, this paper aims to bridge the gap between neuroscience and robotics by reformulating an FEP-based inference scheme—Dynamic Expectation Maximization—into an algorithm that can perform simultaneous state, input, parameter, and noise hyperparameter estimation of any stable linear state space system subjected to colored noises. The resulting estimator was proved to be of the form of an augmented coupled linear estimator. Using this mathematical formulation, we proved that the estimation steps have theoretical guarantees of convergence. The algorithm was rigorously tested in simulation on a wide variety of linear systems with colored noises. The paper concludes by demonstrating the superior performance of DEM for parameter estimation under colored noise in simulation, when compared to the state-of-the-art estimators like Sub Space method, Prediction Error Minimization (PEM), and Expectation Maximization (EM) algorithm. These results contribute to the applicability of DEM as a robust learning algorithm for safe robotic applications. 相似文献
95.
96.
97.
Currently, 188Re is obtained from 188W/188Re chromatographic generator containing alumina which has a limited capacity (~80 mg Wg?1) for 188W. This results in high bolus volumes of 188Re, which often needs to be concentrated before radiolabeling. We have demonstrated the feasibility of using polymer embedded nano crystalline titania (TiP), a novel high capacity sorbent material (~300 mg Wg?1), for developing a 188W/188Re chromatographic generator. A TiP based chromatographic 188W/188Re generator was developed in which 188Re could be eluted with 0.9% saline solution. About 90% of the 188Re could be recovered in the first 4–5 mL of total activity with more than 80% yield. The purity of 188Re is adequate for clinical applications. 相似文献
98.
LC-electrospray ionization (ESI) MS conditions were optimized for the individual chiral separation of 19 compounds of pharmaceutical interest using the macrocyclic glycopeptide-based chiral stationary phases in both polar organic and reversed-phase modes (RPM). The influence of mobile phase composition and MS additive type on sensitivity was investigated for all classes of compounds tested. Compounds with amine or amide groups were efficiently separated, ionized, and detected with the addition of 0.1% (w/w) ammonium trifluoroacetate to the solvent system in either the reversed-phase or polar organic mode (POM). Macrocyclic glycopeptide coupled column technology was initially used to screen all chiral compounds analyzed. Baseline resolution of enantiomers was then achieved with relatively short retention times and high efficiencies on Chirobiotic T, Chirobiotic V or Chirobiotic R narrow bore chiral stationary phases. The polar organic mode offered better limits of detection (as low as 100 pg/ml) and sensitivity over reversed-phase methods. An optimum flow-rate range of 200-400 microl/min was necessary for sensitive chiral LC-ESI-MS analysis. 相似文献
99.
Rubel Chakravarty Meera Venkatesh Ashutosh Dash 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):45-51
A novel electrochemical process to avail clinical grade 99mTc from (n,γ)99Mo has been demonstrated. The electrochemical parameters were optimized to maximize the 99mTc yield with minimal 99Mo contamination. 99Mo/99mTc generators containing up to 29.6 GBq (800 mCi) 99Mo were developed and their performance were extensively evaluated for 10 days without changing the operating conditions.
Very high radioactive concentration of 99mTcO4
− of acceptable quality, commensurate with hospital radiopharmacy requirements could be availed from the system with >90% yield.
The compatibility of the product for the formulation of 99mTc labeled radiopharmaceuticals such as 99mTc-DMSA and 99mTc-EC was found to be satisfactory in terms of high labeling yields. The proposed route represents an important step for enhancing
the scope of accessing clinical grade 99mTc from low specific activity (n, γ)99Mo. 相似文献
100.
B K Basu S M Pattalwar R N Dixit S Y Shete A K Rajarajan L C Gupta R Vijayaraghavan 《Pramana》1988,30(4):L367-L370
We report here the results of our heat capacityC
p measurements on a monophasic material HoBa2Cu3O7−y
. ΔC
p/Tc, the jump inC
p at the superconducting transition temperature (=91 K) of the material is measured to be 31 mJ/mol-K2. 相似文献