Molecular Weight Distributions of Polymer Solutions: Combination of Field Flow Fractionation (FFF) and Analytical Ultracentrifugation (AUC)

Molecular weight, distribution, as well as other molecular characteristics are important drivers in determining the potential behaviors and hence applications of polymeric materials. Out of different methods available for the determination of molecular weight and its distribution, field flow fractionation (FFF) provides absolute molecular weight values and accurate molecular weight distributions. Analytical ultracentrifugation (AUC), on the other hand, relies on the exact density of the polymer materials in solution to determine the accurate molecular weight and its distribution and in the absence of knowledge of exact density, AUC is less accurate than the FFF method. However, combination of the two methods can be achieved to gain insights into the other molecular characteristics of swollen polymer chains. One such example is the determination of the exact density of the swollen polymer chains by the incorporation of the molecular weight information from FFF into AUC analysis. Based on the comparison of the optimized polymer chain density with the bulk density, it was observed that the polyacrylic acid and polyacrylamide chains were swollen in the range of 27 to 29%. Moreover, the FFF and AUC can also complement each other in enhancing the range of characterization possible with the two methods when used separately.     

Highly Efficient and Novel Method for Synthesis of 1,3,5-Triarylbenzenes from Acetophenones

Heteropolyacid–phosphomolybdic acid has been found to be an efficient and recyclable catalyst for cyclotrimerization of acetophenones into 1,3,5-triarylbenzenes in good yields.     

Simple System for Cleavage of Alkene C–C Bond Using Aqueous Sodium Paraperiodate

A simple and mild method for direct conversion of alkenes to corresponding aldehydes has been developed using sodium paraperiodate (Na₃H₂IO₆) in water. The reagent was found to give excellent yields of corresponding aldehydes.     

Simple and Efficient Method for the Preparation of Aryl Azides Using Sonication

An efficient procedure for the preparation of aryl azides using sonication is described. The convenient sonication-mediated azidation protocol is applicable to aryl compounds under mild conditions with aqueous solution of sodium dichloroiodate and sodium azide. Aryl azides were obtained in excellent yields from a variety of aryl compounds in short reaction times without affecting sensitive functional groups.     

Short and Efficient Synthesis of Oxazinone- and Thiazinone-Containing Bicyclic Heteroaromatic Aldehydes

Short and efficient route for the synthesis of oxazinone- and thiazinone-containing bicyclic heteroaromatic aldehydes, which involves the key step of palladium-catalyzed reductive carbonylation, is described. Overall routes for the synthesis of these aldehydes are short, versatile, and scalable with good yields of the product.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

ESIPT inspired fluorescent 2-(4-benzo[d]oxazol-2-yl)naphtho[1,2-d]oxazol-2-yl)phenol: experimental and DFT based approach to photophysical properties

ESIPT inspired fluorescent 2-(4-benzo[d]oxazol-2-yl)naphtho[1,2-d]oxazol-2-yl)phenol was synthesized from 1-amino-3-(1,3-benzoxazol-2-yl)naphthalen-2-ol. Photophysical behavior of the synthesized compound was studied using UV–visible and fluorescence spectroscopy in polar and non-polar solvents. The synthesized naphthoxazolyl benzoxazole is fluorescent and very sensitive to the micro-environment. It shows a single absorption and dual emission in non-polar solvents with large Stokes shift originating from Excited State Intramolecular Proton Transfer while in polar solvents only a single short wavelength emission is observed. Experimental absorption and emission wavelengths are in good agreement with those predicted using the Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)]. The largest wavelength difference between the experimental and computed absorption maxima was 16 nm (acetonitrile) and 7 nm (ethyl acetate, THF, and 1,4-dioxane) in the short and long wavelength regions, respectively. A largest difference of 25 nm was observed for the short wavelength emission in DMF and 22 nm for the longer wavelength emission in chloroform.     

Immunomodulatory and Therapeutic Potential of a Mycelial Lectin from <Emphasis Type="Italic">Aspergillus nidulans</Emphasis>

Lectins bind to surface receptors on target cells, and activate a cascade of events, eventually leading to altered immune status of host. The immunomodulatory potential of purified lectin from Aspergillus nidulans was evaluated in Swiss albino mice treated intraperitoneally with seven different doses of purified lectin. Lectin prevented BSA-induced Arthus reaction and systemic anaphylaxis. The enhanced functional ability of macrophages was evident from respiratory burst activity and nitric oxide production in splenocyte cultures. Interferon-gamma and interleukin-6 levels were significantly up-regulated in treated groups. Maximum stimulatory effect was observed at the dose of 1.5 mg/kg body weight. Therapeutic potential of A. nidulans lectin was assessed against trinitrobenzene sulfonic acid-induced ulcerative colitis in male Wistar rats. Rats pre-treated with 80 mg/kg body weight of purified lectin intraperitoneally prior to colitis induction showed lesser disease severity and recovery within 7 days, while rats post-treated with the same dose showed recovery in 11 days. The results demonstrate immunomodulatory effects of A. nidulans lectin in Swiss albino mice, resulting in improved immune status of the animals and unfold its curative effect against ulcerative colitis in rat model. This is the first report on immunomodulatory and therapeutic potential of a lectin from microfungi.     

Influence of Operating Parameters on Unbalance in Rotating Machinery Using Response Surface Method

Wide range of rotating machinery contains an inherent amount of unbalance which leads to increase in the vibration level and related faults. In this work, the effect of different operating conditions viz. the unbalanced weight, radius, speed and position of the rotor disc on the unbalance in rotating machine are studied experimentally and analyzed by using Response Surface Methodology (RSM). RSM is a technique which consists of mathematical and statistical methods to develop the relationship between the inputs and outputs of a system by distinct functions. L27 Orthogonal Array (OA) was developed by using Design of Experiments (DOE) according to which experimentation has been carried out. Three accelerometer sensors were mounted to record the vibration responses (accelerations) in radially vertical, horizontal and axial directions. The responses recorded as root mean square values are then analysed using RSM. The relationship between response and operating factors has been established by developing a second order, non-linear mathematical model. Analysis of variance (ANOVA) has been performed for verification of the developed mathematical models. Results obtained from the analysis show that the unbalance weight and speed are most significant operating conditions that contribute the most to the effect the unbalance has on the rotating spindle.     

Biomimetic Synthesis of Silver Nanoparticle Using Leaf Extract of Mangifera Indica and Their Antibacterial Efficacy

The aim of this study to focused on bioinspired synthesis of silver nanoparticles (AgNPs) as a viable alternative to eradicate the existing physicochemical processes. In this context, the bioinspired AgNPs were synthesized using leaf extract of M. indica. Optimization of the experimental conditions for the rapid and high yield of AgNPs in minimum investment of time and expense have been carried out along with their antibacterial efficacy evaluated. For this reason, the variation of parameters like the concentration of the silver precursors, reducing agent, time, pH, and temperature of synthesis were realized. Synthesized AgNPs were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) techniques. UV-Visible spectra gave surface plasmon resonance (SPR) at 440 nm for AgNPs. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques were further confirmed the synthesis and crystalline nature of AgNPs respectively. Transmission electron microscopy (TEM) observed spherical shapes of synthesized AgNPs within range 5～20 nm. The results of the current study indicate that optimization process play a pivotal role in the AgNPs synthesis and biogenic synthesized AgNPs might be used against bacterial pathogens.     

Ultracold Rydberg atoms for efficient storage of terahertz frequency signals using electromagnetically induced transparency

Quantum communication with terahertz (THz) frequency signals has many advantages like reduced attenuation and scintillation effects in certain atmospheric conditions along with very high level of data security. In this work, we propose a scheme to realize Quantum Memory (QM) for efficient storage of terahertz (THz) frequency signals using Electromagnetically Induced Transparency (EIT) in an ultracold atomic medium of ⁸⁷Rb Rydberg atoms prepared in a Two Dimensional Magneto Optical Trap (2D-MOT). The uniqueness of our scheme lies in the choice of the energy levels involved in the EIT process, all three of which have been chosen to be the Rydberg levels (enabling signal beam to be in THz) in a lambda type arrangement. This first of its kind proposal reveals that atomic media are a potential candidate for devising QMs which can store THz frequency signals. We have estimated that the Optical Depth (OD) in our scheme can reach a very high value of 690, very high maximum obtainable storage efficiency (η) of ～99%, the group velocity ($v_g$) can be as low as 5.07 × 10³ m/s, and the Delay Bandwidth Product (DBP) can be as high as 9.5. All of these estimates emphasize the feasibility of our scheme as a QM device for efficient storage of THz pulses.