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71.
Indicator displacement assays (IDAs) are now a popular method for converting most any synthetic receptor into an optical sensor. In this review many such assays are highlighted, along with biological counterparts. The focus is upon colorimetric, fluorescent, and metal containing IDAs. The power of the method can be readily appreciated by the large diversity of analytes that have been targeted with this technique. It is clear that the method is now well accepted and will continue to be one of many methods used to create optical detection methods from synthetic receptors. 相似文献
72.
Classification on high-dimensional data with thousands to tens of thousands of dimensions is a challenging task due to the high dimensionality and the quality of the feature set. The problem can be addressed by using feature selection to choose only informative features or feature construction to create new high-level features. Genetic programming (GP) using a tree-based representation can be used for both feature construction and implicit feature selection. This work presents a comprehensive study to investigate the use of GP for feature construction and selection on high-dimensional classification problems. Different combinations of the constructed and/or selected features are tested and compared on seven high-dimensional gene expression problems, and different classification algorithms are used to evaluate their performance. The results show that the constructed and/or selected feature sets can significantly reduce the dimensionality and maintain or even increase the classification accuracy in most cases. The cases with overfitting occurred are analysed via the distribution of features. Further analysis is also performed to show why the constructed feature can achieve promising classification performance. 相似文献
73.
Giang Binh Truong Dr. Hung Tuan Duong Prof. Dr. Loi Duc Vu Dr. Thao Thi Huong Hoang 《欧洲无机化学杂志》2023,26(31):e202300371
The electrochemical reduction reaction of nitrogenous species such as NO3− (NO3RR) and N2 (NRR) is a promising strategy for producing ammonia under ambient conditions. However, low activity and poor selectivity of both NO3RR and NRR remain the biggest problem of all current electrocatalysts. In this work, we fabricated Cu-nanosphere film with a high surface area and dominant with a Cu(200) facet by simple electrodeposition method. The Cu-nanosphere film exhibits high electrocatalytic activity for NO3RR and NRR to ammonia under ambient conditions. In the nitrate environment, the Cu-nanosphere electrode reduced NO3− to yield NH3 at a rate of 5.2 mg/h cm2, with a Faradaic efficiency of 85 % at −1.3 V. In the N2-saturated environment, the Cu-nanosphere electrode reduced N2 to yield NH3 with the highest yield rate of 16.2 μg/h cm2 at −0.5 V, and the highest NH3 Faradaic efficiency of 41.6 % at −0.4 V. Furthermore, the Cu-nanosphere exhibits excellent stability with the NH3 yield rate, and the Faradaic efficiency remains stable after 10 consecutive cycles. Such high levels of NH3 yield, selectivity, and stability at low applied potential are among the best values currently reported in the literature. 相似文献
74.
New isoxazolidines were synthesized in good to excellent yields by 1,3-dipolar cycloaddition of N-vinylamide dipolarophiles and nitrones. Strikingly, solvent-free conditions gave high conversion and yields, shortened reaction time, and minimized degradation products. N-Vinyloxazolidin-2-one and its analogues used in these cycloaddition reactions were conveniently prepared in excellent yields by a modified version of Buchwald's one-step copper-catalyzed vinylation using vinyl bromide. From the adducts, a two-step access to various unsymmetric aspartate derivatives was also described. 相似文献
75.
The objective of this work was to form water-soluble 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives. Sulfonation conditions were developed for several BODIPY dyes to give the monosulfonated products 1a-3a and the disulfonated products 1b-3b. Compounds 1 are functionalized with an aryl iodide for organometallic couplings. Similarly, 2 has an aromatic bromide but also two chlorine atoms that could be replaced via SNAr reactions. The amine 3 is amenable to couple to biomolecules via acylation reactions. A diazotization/azide reaction sequence was used to convert the amines 3 into azides 4; the latter may be functionalized via click reactions as illustrated by conversion of 4b into 5. Compound 5 was designed to have an acid-functional group to facilitate activation and coupling to amines. Spectral data for these materials indicate they are highly fluorescent probes in aqueous environments. 相似文献
76.
Nguyen Van Thang Le Binh An Huynh Nguyen Phong Thu Le Cong Hao 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):829-838
Journal of Radioanalytical and Nuclear Chemistry - 226Ra levels in rice, soil, fertilizers, and water samples were analysed in 16 paddy fields in the Mekong Delta region. Levels of this... 相似文献
77.
Doan Binh 《Radiation Physics and Chemistry》2012,81(7):906-912
The formation of carboxymethyl starch (CMS) nanogel with 50 nm less particle size was carried out through a radiation crosslinked process on the electron beam (EB) linear accelerator. Changes of intrinsic viscosities and weight averaged molecular weight in the CMS concentration, which ranged from 3 to 10 mg ml?1 in absorbed doses were investigated. There were some new peaks in the 1H NMR spectra of CMS nanogel compared with those of CMS polymer. These results were anticipated that the predominant intramolecular crosslinking of dilute CMS aqueous solution occurred while being exposed to a short intense pulse of ionizing radiation. Hydrodynamic radius (often called particle size, Rh) and distribution of particle size were measured by a dynamic light scattering technique. The radiation yield of intermolecular crosslinking of CMS solution was calculated from the expression of Gx (Charlesby, 1960, Jung-Chul, 2010). The influence of the “size effect” was demonstrated by testing culture of Lactobacillus bacteria on MRS agar culture medium containing CMS nanogel and polymer. Results showed that the number of Lactobacillus bacteria growing on nanogel containing culture medium is about 170 cfu/ml and on polymer containing culture medium is only 6 cfu/ml. 相似文献
78.
Nagle PS Quinn SJ Kelly JM O'Donovan DH Khan AR Rodriguez F Nguyen B Wilson WD Rozas I 《Organic & biomolecular chemistry》2010,8(24):5558-5567
Biophysical studies have been carried out on a family of asymmetric guanidinium-based diaromatic derivatives to assess their potential as DNA minor groove binding agents. To experimentally assess the binding of these compounds to DNA, solution phase biophysical studies have been performed. Thus, surface plasmon resonance, UV-visible spectroscopy and circular and linear dichroism have been utilized to evaluate binding constants, stoichiometry and mode of binding. In addition, the thermodynamics of the binding process have been determined by using isothermal titration calorimetry. These results show significant DNA binding affinity that correlates with the expected 1?:?1 binding ratio usually observed for minor groove binders. Moreover, a simple computational approach has been devised to assess the potential as DNA binders of this family of compounds. 相似文献
79.
A novel method of transamidation of carboxamides with amines using catalytic amounts of readily available boric acid under solvent-free conditions has been developed. The scope of the methodology has been demonstrated with (i) primary, secondary, and tertiary amides and phthalimide and (ii) aliphatic, aromatic, cyclic, acyclic, primary, and secondary amines. 相似文献
80.