Somdeb Chanda  Ajanto Kumar Hazarika  Navnil Choudhury  Sk Anarul Islam  Rishabh Manna  Santanu Sabhapondit  Bipan Tudu  Rajib Bandyopadhyay 《Journal of Chemometrics》2019,33(10)

Caffeine is an important component that determines the quality of tea, and its rapid estimation is very much needed for the industry. In this pursuit, a near‐infrared (NIR) spectroscopy‐based technique for the estimation of caffeine is developed and presented in this paper. On the basis of responses of the different bonds present in caffeine, four specific wavelength windows—(a) 1075 to 1239.5 nm (C―H stretch second overtone); (b) 1339.25 to 1440.75 nm (C―H stretch and C―H deformation); (c) 1640.25 to 1700 nm (C―H stretch first overtone, ═CH & amp; ―CH₃ asymmetric); and (d) 900 to 1700 nm (whole range of the spectrometer)—were analyzed in details for model development and to obtain the effective wavelength (EW). Five different preprocessing techniques followed by two regression techniques—(a) the partial least‐squares (PLS) and (b) the support vector regression (SVR) were implemented on raw data for analysis. Comparing all the models, the wavelength band of 1075 to 1239.5 nm and 1339.25 to 1440.75 nm were found to produce satisfactory results. The best discrimination result was obtained using the combination of standard normal variate (SNV) preprocessing with SVR at the 1075 to 1239.5 nm wavelength region. The SVR regression with 105 samples in the training set and 15 samples in the testing set resulted in the performance parameters as RMSECV = 0.134, RMSEP = 0.069, r_cv² = 0.869, r_p² = 0.65, and RPD = 5.626 at 1075 to 1239.5 nm, whereas the PLS model produced the best RMSECV = 0.287, RMSEP = 0.077, r_cv² = 0.637, r_p² = 0.675, and RPD = 5.218 at 1339.25 to 1440.75‐nm wavelength band.  相似文献   

    

Mayuri Choudhuri  Debasmita Choudhury  Jayanta Mukhopadhyay  Madhumita Mukhopadhyay 《Macromolecular Symposia》2019,388(1)

Ion conduction process is highly dependent on the synthesis and type of polymer salt composite. Composites are synthesized using low melting poly(ethylene oxide) (PEO) salts (NH₄I and KBr) loaded with 10 wt% treated silica as passive filler. Highest ionic conductivity of ≈10⁻³ S cm⁻¹ with least bulk resistance is obtained from PEO–NH₄I (20%) composite consisting of treated silica as filler. The aim of the present article resides in the selection and usage of salt effectively wherein highly conductive (like PEO–NH₄I‐treated SiO₂) and highly dielectric (like PEO–KBr‐treated SiO₂) films can be utilized as per the needs of application. The novelty of the research work is imbibed in the long‐term endurance analyses of such composites for 2000 h. Addition of silica is reported to significantly enhance the cyclability of PEO–ammonium salt based electrolyte significantly up to 2000 h. Detailed study is carried out in terms of long‐term analyses and correlated with SEM morphology.  相似文献   

    

Utsav Choudhury  Martin Gallauer Alves de Souza 《代数通讯》2019,47(8):3202-3228

In this note we study the local projective model structure on presheaves of complexes on a site, that is, we describe its classes of cofibrations, fibrations, and weak equivalences. In particular, we prove that the fibrant objects are those satisfying descent with respect to all hypercovers. We also describe cofibrant and fibrant replacement functors with pleasant properties.  相似文献   

    

Nicholas Flynn  Ashish Ranjan  Joshua D. Ramsey 《Macromolecular bioscience》2019,19(10)

Reactive oxygen species (ROS) forming enzymes are of significant interest as anticancer agents due to their potent cytotoxicity. A key challenge in their clinical translation is attaining site‐specific delivery and minimizing biodistribution to healthy tissues. Here, complexes composed of the ROS enzyme glucose oxidase (GOX), poly‐l ‐lysine‐grafted‐polyethylene glycol (PLL‐g‐PEG), and anti‐prostate specific membrane antigen (anti‐PSMA) monoclonal antibody are synthesized for localized delivery and uptake in prostate cancer cells. Formation of anti‐PSMA‐PLL‐g‐PEG/GOX results in nanoscale complexes ≈30 nm in diameter with a ζ‐potential of 6 mV. The anti‐PSMA‐PLL‐g‐PEG/GOX complexes show significant cytotoxicity (≈60% reduction in cell viability) against PSMA‐expressing LNCaP cells compared to unmodified GOX. Importantly, cytotoxicity in LNCaP cells occurrs concurrently with anti‐PSMA‐PLL‐g‐PEG/GOX uptake and increases in intracellular generation of ROS. These results demonstrate that cytotoxicity of ROS inducing enzymes can be enhanced by intracellular delivery compared to equivalent concentrations of free enzyme, providing a novel means for cancer therapy.  相似文献   

    

Nilotpal Choudhury  Nishant Kumar Shekhar  Anirban Dhar  Ranjan Sen 《physica status solidi (a)》2019,216(20)

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Li Zhang  Yihao Yang  Mengjia He  Hai‐Xiao Wang  Zhaoju Yang  Erping Li  Fei Gao  Baile Zhang  Ranjan Singh  Jian‐Hua Jiang  Hongsheng Chen 《Laser u0026amp; Photonics Reviews》2019,13(11)

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Suchismita Datta Sarkar  Basana Choudhury 《Molecular Crystals and Liquid Crystals》2018,665(1):91-99

Optical and static dielectric studies on a terminally fluorinated liquid crystalline compound have been carried out. Measurements of temperature variation of refractive indices of the compound are done by using thin prism method. A four-parameter model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the compound with the theoretical ones. Refractive index and density data are utilized for determination of orientational order parameter. The temperature variation of dielectric permittivities of the compound are measured by a LCR meter.  相似文献   

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Rajib Choudhury  Vaidhyanathan Ramamurthy 《Journal of Physical Organic Chemistry》2018,31(5)

In this study, inclusion of 10 guest molecules, adamantyl and naphthyl carboxylic acids with different structural and electronic properties, within a synthetic cavitand octa acid was probed by isothermal calorimetry, 1D and 2D ¹H nuclear magnetic resonance spectroscopy, and molecular dynamic simulations. Under the condition of the experiments (pH ~ 8.7), the guests were included as carboxylate anions with the polar anionic head group facing water and hydrophobic carbon skeleton buried within the cavitand, forming 1:1 host to guest complexes. Importance of weak interactions between the guest and the cavitand interior is reflected in the measured negative ΔH values. Although ΔH was negative for all guests, ΔS was positive for adamantyl guests and negative for naphthyl guests. Quite likely the difference in hydrophobicity between the 2 sets of molecules and the strength of interaction between the guest and the host are responsible for the sign difference in ΔS between the 2 series. The importance of steric factor during inclusion of naphthyl carboxylic acids within octa acid cavity is brought out by the difference in thermodynamic parameters between the 1‐ and 2‐substituted naphthyl carboxylic acids; 2‐naphthyl carboxylic acids that can penetrate deeply have larger −ΔH and 1‐naphthyl carboxylic acids that can only enter the cavity in an angle have smaller −ΔH. As expected, based on the well‐known concept of “enthalpy‐entropy compensation,” the molecules that have large −ΔH are accompanied by large −ΔS.  相似文献   

    

Yashwantsinh S. Jadeja  Khushal M. Kapadiya  Hetal J. Jebaliya  Anamik K. Shah  Ranjan C. Khunt 《Magnetic resonance in chemistry : MRC》2017,55(6):589-594

Hesperidin is flavonoid molecule found in citrus fruits (Citrus reticulata), especially difficult to extract, classify and characterize. Present work is to study the unresolved relative configuration of Hesperidin through the dihedral angle, coupling constant and different NMR techniques. The Karplus equation and its modifications have been originated from the valence bond theory and associated with dihedral angle and coupling constant. The result data set of calculated dihedral angle can probe significant method to assign the virtual configuration of natural products and also resolved stereochemistry of Hesperidin at C‐2 position in. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

    

Shrivats Semwal  Dr. Joyanta Choudhury 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(20):5648-5652

Disclosed here is a molecular switch which responds to acid-base stimuli and serves as a bi-state catalyst for two different reactions. The two states of the switch serve as a highly active and poorly active catalyst for two catalytic reactions (namely a hydrogenation and a dehydrogenative coupling) but in a complementary manner. The system was used in an assisted tandem catalysis set-up involving dehydrogenative coupling of an amine and then hydrogenation of the resulting imine product by switching between the respective states of the catalyst.  相似文献