Brownian dynamics of rigid body by fluctuating hydrodynamic equations

In this work, Brownian dynamics of rigid body in an incompressible fluid with fluctuating hydrodynamic equations is presented. To demonstrate the Brownian motion of rigid body, fluctuating hydrodynamic equations have been coupled with equations of motion of rigid body. Thermal fluctuation is included in the fluid equations via random stress terms unlike the random terms in the conventional Brownian dynamics type approach. Calculation of random stress terms in the fluid is easier in comparison to the random terms in the particle motion. Direct numerical simulation for the Brownian motion of rigid body with a meshfree framework is analysed. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Examination of (e,2e) scattering models by comparison of momentum profiles of noble gases between experiment and theory

Momentum profiles have been measured for the two outermost atomic orbitals of noble gases, Ar, Kr and Xe, at incident electron energy of about 2 keV using a newly developed multichannel (e,2e) spectrometer. The experimental results exhibit significantly improved statistics compared with those achieved in previous studies while covering a wide range of momenta up to 3.6 a.u. The results are compared with theoretical calculations using four (e,2e) scattering models, the plane-wave impulse and Born approximations (PWIA and PWBA), and the distorted-wave impulse and Born approximations (DWIA and DWBA). The DWIA and DWBA scattering models have been found to satisfactorily reproduce the experimental momentum profiles in terms of both shape and intensity over the entire momentum range covered, indicating the importance of distorted wave effects for quantitatively describing (e,2e) reaction.     

Kinetics and Mechanism of Polymerization of Methyl Methacrylate using Selenonium Ylide as a Novel Initiator

Polymerization of Methyl methacrylate (MMA) was carried out in dioxan at 60 ± 1°C for 90 min in dilatometer under nitrogenous atmosphere using diphenylselenonium 2,3,4,5-tetraphenylcyclopentadienylide (selenonium ylide) as a novel initiator. The exponent values for initiator and monomer were computed as 0.32 and 1.59, respectively. The overall activation energy and k_p ²/k_t were found 42.1 k J mol^?1 and 0.819 l mol^?1s^?1, respectively. The free radical mode of polymerization was confirmed by ESR spectroscopy. The FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques were used for its characterization.     

The Antiproliferative and Apoptotic Effect of a Novel Synthesized S-Triazine Dipeptide Series,and Toxicity Screening in Zebrafish Embryos

Several derivatives containing morpholine/piperidine, anilines, and dipeptides as pending moieties were prepared using s-triazine as a scaffold. These compounds were evaluated for their anticancer activity against two human breast cancer cell lines (MCF-7 and MDA-MB-231), a colon cancer cell line (HCT-116), and a non-tumorigenic cell line (HEK 293). Tamoxifen was used as a reference. Animal toxicity tests were carried out in zebrafish embryos. Most of these compounds showed a higher activity against breast cancer than colon cancer. Compound 3a—which contains morpholine, aniline, and glycylglycinate methyl ester—showed a high level of cytotoxicity against MCF-7 cells with IC₅₀ values of less than 1 µM. This compound showed a much lower level of toxicity against the non-tumorigenic HEK-293 cell line, and in the in vivo studies using zebrafish embryos. Furthermore, it induced cell cycle arrest at the G2/M phase, and apoptosis in MCF-7 cells. On the basis of our results, 3a emerges as a potential candidate for further development as a therapeutic drug to treat hormone receptor-positive breast cancer.     

A solvent-free synthesis of ethyl 3,5-diaryl-1H-pyrrole-2-carboxylates via triethylphosphite mediated reductive cyclization of ethyl 2-nitro-5-oxo-3,5-diarylpentanoates under microwave irradiation

Ethyl 3,5-diaryl-1H-pyrrole-2-carboxylates have been synthesized in good yields from ethyl 2-nitro-5-oxo-3,5-diarylpentanoates by treatment with triethylphosphite under microwave irradiation. The integrity of the mechanism proposed has been augmented by ³¹P NMR and EIMS experiments.     

Recent advance: Sulfur ylides in organic synthesis

Sulfur ylides are versatile structures that display various characteristics and participate in a myriad of reactions to produce simple, effective, and sometimes stereoselective reactions toward synthesizing sulfur-containing compounds. Nonetheless, their fulfillment tremendous developments have been made in this field in the past few decades. In this comprehensive review, luminosity is illuminated on the application of sulfur ylides involved in various domino, cascade annulation reactions, and carbene trapping reagents with chameleonic reactivity. In the past numerous decennary, chemists have used sulfur ylides in solvent-dependent, rhodium catalyzed, dealkylative intercepted, photochemical reaction, halotrifluoromethylation, benzannulation, amidation various name reactions such as Mizoroki–Heck, Suzuki–Miyaura, and Sommelet–Hauser rearrangements. Moreover, other prime applications include metal catalysis, epoxidation of carbonyl compounds, acylmethylation, cyclomerization, oxidation, and insertion reactions. Additionally, some sulfur ylides are extremely useful structures that play a major role in the synthesis of various medicinally active heterocycles structural motifs. This review article discusses all these reactions, their proposed mechanisms, and their application in the current scenario, at length. This tutorial review concludes by providing a future outlook on the investigation into sulfur ylides and various other compounds synthesized using it have great potential to be used in industries, laboratories, pharmaceutical companies, drug production, clinical use, medicinal chemistry, and agrochemical purposes.     

Designing Swellable Beads of Alginate and Gelatin for Controlled Release of Pesticide (Cypermethrin)

In the present study biopolymeric beads of sodium alginate and gelatin were prepared by employing CaCl₂ as a crosslinking agent. A series of such microspheres of different compositions were prepared by varying the amounts of sodium alginate, gelatin and CaCl₂ in the feed mixture. The beads were loaded with an insecticide like cypermethrin. The prepared loaded and unloaded beads were characterized by FTIR spectral and Environmental scanning electron microscopy (ESEM) techniques, to gain insight into the molecular structure and morphology of beads, respectively. The swelling experiments were performed for different composition of beads and at varying pH and temperature of the swelling media. The swelling controlled release of insecticide was also investigated for 8 days in bi-distilled water as a release medium. The release experiments were performed under the static and varying experimental conditions and the data obtained were fitted to Fick's equation to evaluate diffusion coefficients of insecticide. The results were further analyzed by Fick's power law equation, and the possible mechanisms of the insecticide release were explored at different experimental conditions. Soil–pot experiments were also performed to demonstrate the applicability of the present controlled release technique to agricultural fields.     

Mass spectrometry-based metabolomic fingerprinting for screening cold tolerance in Arabidopsis thaliana accessions

The availability of rapid and reliable tools for monitoring of plants’ cold tolerance is a prerequisite for research aimed at breeding of cold-tolerant crop plants. Therefore, we have tested the capacity of metabolomics-based methods employing ultra-high-performance liquid chromatography (UHPLC)–mass spectrometry and direct analysis in real time–mass spectrometry for high-throughput screening of cold tolerance in eight differentially cold-tolerant accessions of Arabidopsis thaliana. Metabolomic fingerprinting of leaf tissues was performed in methanolic extracts for (1) 6-week-old non-acclimated (NAC) plants grown at room temperature, (2) NAC plants cold-acclimated (ACC) at 4 °C for 2 weeks, and (3) cold-acclimated plants given sub-zero-temperature treatments by slow cooling at ?4 °C for 8 h. The generated chromatograms and mass spectra were processed with the use of multivariate statistical analysis employing principal component analysis (PCA) and linear discriminant analysis. The PCA of metabolomic fingerprints classified the investigated A. thaliana accessions into three categories with low, intermediate, and high cold tolerance for both the cold-acclimated and the sub-zero-temperature-treated plants. This indicates the potential application of metabolomics-based fingerprinting for measuring cold tolerance in the cold-acclimated state, i.e., without treating plants at freezing temperatures that is required by currently available methods. Furthermore, we employed UHPLC coupled to the quadrupole-time-of-flight mass spectrometry to identify characteristic metabolites in ACC state and found the abundance of gluconapin and flavon-3-ol glycosides, respectively, in the cold-sensitive and the cold-tolerant accessions.     

Development of a rapid normal-phase LC-positive ion APCI-MS method for simultaneous detection and quantitation of cholesterol, androst-4-ene-3,1 7-dione, and androsta-1,4-diene-3,17-dione

This paper describes the development of a normal-phase liquid chromatograph-UV-diode array detection-positive ion atmospheric pressure chemical ionization-mass spectrometry method for the simultaneous identification and quantitation of cholesterol, androst-4-ene-3,17-dione (AD), and androsta-1,4-diene-3,17-dione (ADD) in fermentation broths. The compounds detected under positive ion atmospheric pressure chemical ionization on a mass spectrometer by selected ion monitoring are separated by normal-phase high-performance liquid chromatography. [M+H]+ ions are taken into consideration for quantitation of AD and ADD, and [M-H2O+H]+ ions are considered for quantitation of cholesterol. The compounds are analyzed on a Si60 silica (5 microm, 125 x 4-mm i.d.) Merck column using a 2:3 isocratic mixture of isopropyl alcohol and hexane. The calibration curves resulting from the reference compounds in the concentration range of 100-5000 pg on column exhibit a good linear correlation (r2 > or = 0.996). The method is validated by analyzing six replicates of broth samples fortified with three compounds, namely, cholesterol, AD, and ADD, at 0.050 and 0.5 microg/g levels. The mean recoveries for the fortifications range from 90% to 98% with relative standard deviations in the range of 3.36% to 9.78%. The method is developed to study the qualitative as well as quantitative conversion of cholesterol to AD and ADD by a microorganism identified as Nocardia sp. These studies helped the investigation of the reaction kinetics, which showed that the molar biotransformation of cholesterol into AD and ADD was 21%, even when the reaction was prolonged for 96 h.     

Charge Transfer in 1,8-Naphthalimide: A Combined Theoretical and Experimental Approach

Photophysics of 1,8-naphthalimide (NAPMD) in different solvents has been delineated in this paper. Theoretically calculated bond distance of N–H and C=O groups rule out any intramolecular proton transfer in the excited state. Concomitant increase in negative charge on O atom compared to N atom and dipole moment hints at possible intramolecular charge transfer. Progressive redshift with polarity of solvents in emission and absorption spectra also confirms the theoretical prediction. Weakening of N–H bond helps hydrogen abstraction and anion formation in water with decay time of 2.54 ns through intermolecular proton transfer. This was corroborated from the ground state photoexcitation of laboratory synthesized anion of NAPMD. Amide hydrolysis in higher pH and excess proton availability at low pH are responsible for anion emission quenching. A possible electron transfer diminishes phosphorescence at 77 K with changing pH.