Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H01:13

meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H

6.7K
All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for...
6.7K
2° Amines to N-Nitrosamines: Reaction with NaNO201:20

2° Amines to N-Nitrosamines: Reaction with NaNO2

5.5K
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
5.5K
SN2 Reaction: Kinetics02:14

SN2 Reaction: Kinetics

10.3K
Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
10.3K
SN2 Reaction: Mechanism02:27

SN2 Reaction: Mechanism

17.5K
The kinetic studies of SN2 reactions suggest an essential feature of its mechanism: it is a single-step process without intermediates. Here, both the nucleophile and the substrate participate in the rate-determining step.
The presence of the more electronegative halogen in the substrate creates a polarized carbon-halide bond. The halide pulls the electron cloud generating an electrophilic center at the carbon atom. Thus, the carbon atom carries a partial positive charge while the halide has a...
17.5K
SN2 Reaction: Transition State02:26

SN2 Reaction: Transition State

12.0K
An SN2 reaction of an alkyl halide is a single-step process in which bond formation between the nucleophile and the substrate and bond breaking between the substrate and the halide occurs simultaneously through a transition state without forming an intermediate.
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
12.0K
SN2 Reaction: Stereochemistry02:23

SN2 Reaction: Stereochemistry

11.8K
In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
11.8K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Weighted Sparse Partial Least Squares With Joint Sample and Feature Selection for Integrating Multi-Omics Data.

IEEE transactions on computational biology and bioinformatics·2025
Same author

Contrastive independent subspace analysis network for multi-view spatial information extraction.

Neural networks : the official journal of the International Neural Network Society·2025
Same author

Tensorized Bipartite Graph Learning for Multi-View Clustering.

IEEE transactions on pattern analysis and machine intelligence·2022
Same author

Non-Greedy L21-Norm Maximization for Principal Component Analysis.

IEEE transactions on image processing : a publication of the IEEE Signal Processing Society·2021
Same author

Labeled-Robust Regression: Simultaneous Data Recovery and Classification.

IEEE transactions on cybernetics·2020
Same author

Revisiting L<sub>2,1</sub>-Norm Robustness With Vector Outlier Regularization.

IEEE transactions on neural networks and learning systems·2020

Related Experiment Video

Updated: Feb 8, 2026

Recognition of Epidermal Transglutaminase by IgA and Tissue Transglutaminase 2 Antibodies in a Rare Case of Rhesus Dermatitis
10:27

Recognition of Epidermal Transglutaminase by IgA and Tissue Transglutaminase 2 Antibodies in a Rare Case of Rhesus Dermatitis

Published on: December 15, 2011

25.0K

R1 -2-DPCA and Face Recognition.

Quanxue Gao, Sai Xu, Fang Chen

    IEEE Transactions on Cybernetics
    |July 12, 2018
    PubMed
    Summary

    We introduce R1-2DPCA, a robust dimensionality reduction method for image analysis. This novel approach enhances feature extraction by being resilient to outliers and encoding discriminant information, outperforming existing techniques.

    More Related Videos

    Novel Object Recognition Test for the Investigation of Learning and Memory in Mice
    08:52

    Novel Object Recognition Test for the Investigation of Learning and Memory in Mice

    Published on: August 30, 2017

    77.6K
    Behavioral Tasks for Examining Identity Recognition In Mice
    06:58

    Behavioral Tasks for Examining Identity Recognition In Mice

    Published on: February 7, 2025

    1.2K

    Related Experiment Videos

    Last Updated: Feb 8, 2026

    Recognition of Epidermal Transglutaminase by IgA and Tissue Transglutaminase 2 Antibodies in a Rare Case of Rhesus Dermatitis
    10:27

    Recognition of Epidermal Transglutaminase by IgA and Tissue Transglutaminase 2 Antibodies in a Rare Case of Rhesus Dermatitis

    Published on: December 15, 2011

    25.0K
    Novel Object Recognition Test for the Investigation of Learning and Memory in Mice
    08:52

    Novel Object Recognition Test for the Investigation of Learning and Memory in Mice

    Published on: August 30, 2017

    77.6K
    Behavioral Tasks for Examining Identity Recognition In Mice
    06:58

    Behavioral Tasks for Examining Identity Recognition In Mice

    Published on: February 7, 2025

    1.2K

    Area of Science:

    • Computer Vision
    • Machine Learning
    • Data Science

    Background:

    • 2-D principal component analysis (2-DPCA) is a dimensionality reduction technique for image classification.
    • Standard 2-DPCA is sensitive to outliers, limiting its real-world applicability.
    • Robust methods are needed to improve the reliability of 2-DPCA.

    Purpose of the Study:

    • To develop an efficient and robust dimensionality reduction method for image feature extraction.
    • To address the limitations of existing 2-DPCA methods in handling outliers.
    • To enhance classification performance by incorporating discriminant information.

    Main Methods:

    • Proposed R1-2DPCA, a novel robust method utilizing R1-norm for maximizing projected data variance.
    • Developed a non-greedy iterative algorithm with a closed-form solution and good convergence properties.
    • Employed nuclear norm as a distance metric in the classification phase to further improve performance.

    Main Results:

    • R1-2DPCA demonstrates robustness to outliers in feature extraction.
    • The proposed method effectively encodes discriminant information, improving classification.
    • Experimental results on face databases show superiority over existing robust 2-DPCA methods.

    Conclusions:

    • R1-2DPCA offers an efficient and robust solution for dimensionality reduction in image analysis.
    • The method successfully balances outlier robustness with the encoding of discriminant features.
    • The integration of nuclear norm further boosts classification accuracy, validating the approach.