Are large micelles rigid or flexible? A reinterpretation of viscosity data for micellar solutions

Surfactant solutions in which large cylindrical micelles form are characterized by two essential features, namely, they are polydisperse and the average micelle size is proportional to the square root of the micelle concentration. These features of the cylindrical micelles imply that the intrinsic viscosities of these micellar solutions should also depend on the concentration of micelles. This fact has been ignored in all past treatments of micellar viscosity data. Here, viscosity data available in literature were reexamined in terms of concentration-dependent intrinsic viscosity so as to evaluate the rigidity or the flexibility of the large micelles. It is found that the interpretation of viscosity data assuming that the large micelles are rigid rods is in very good agreement with the theoretically anticipated essential features of large micelles. It is concluded that large micelles can be satisfactorily represented by rigid rods rather than by flexible rods or coils.     

Molecular dynamics,root-mean-square amplitudes,statistical thermodynamics,and molecular polarizability for the isotopic species of dioxygen monofluoride

A brief survey of vibrational spectral studies for the four isotopic species of dioxygen monofluoride has been made. On the basis of group theoretical considerations, symmetry coordinates have been constructed and kinetic energy matrices (orG matrix elements), potential energy matrices, and secular equations have been derived to calculate the valence force constants. The mean-square amplitudes and root-mean-square amplitudes for both the bonded and nonbonded atom pairs have been calculated at the room temperature. On the basis of a rigid rotator and harmonic oscillator model, enthalpy function, free enthalpy function, entropy, and heat capacity have been calculated from 200 to 2000 °K for all the four isotopic species. On the basis of a delta-function potential model based on the variational method and delta-function electronic wave functions, the bond parallel components, the bond perpendicular components, the contribution by the nonbonding electrons, and the average molecular polarizability have been calculated. The results obtained from these studies clearly confirm a double bond character for the oxygen—oxygen distance and a bond order of less than one-half for the oxygen—fluorine distance. The results have been discussed in relation to the nature of the two characteristic bonds involved in this molecular system.     

Magnetic and151Eu mössbauer studies on EuTGa (T=Pd AND Pt) compounds

The compounds EuPdGa and EuPtGa show lattice volume anomaly indicating the abnormal valence state of Eu. in these compounds. Magnetization studies reveal that these compounds are magnetically ordered with a moment of 7 _B/f.u. at 5K. The Curie temperatures obtained from the low field ac susceptibility measurements are 38K for EuPdGa and 36K for EuPtGa.¹⁵¹Eu Mössbauer studies at 300K gave large negative isomer shifts (relative to SmF₃) and show a hyperfine split pattern at 4.2K in both the compounds. These results suggest that Eu is in a divalent state in EuPdGa and EuPtGa.     

Formation of benzo[a]phenoxazine derivatives by triethylphosphite-induced deoxygenation of 1-(2-nitrophenoxy) and 2-(2-nitrophenoxy)naphthalenes

Reaction of 1-(2-nitrophenoxy)naphthalene or its β-isomer $\text{7}$ with triethylphosphite produces benzo[a]phenoxazines $\text{8}$ and $\text{10}$, through the intermediate $\text{6}$.     

Extraction and characterization of alkali-treated red coconut empty fruit bunch fiber

This article discusses the extraction and characterization of new natural fiber extracted from red coconut empty fruit bunch. The physicochemical, mechanical, and thermal properties of alkali-treated red coconut empty fruit bunch fibers (ARCEFBFs) were reported and compared with other natural fibers for the first time. Cellulose content (65.02 wt%), wax (0.32 wt%), density (1.421 g/cc), and tensile strength (1299.49 MPa) were identified in ARCEFBFs. Fourier transform infrared spectroscopy and X-ray diffraction analysis confirmed that ARCEFBFs are rich in cellulose content with crystallinity index of 53.6%. Thermogravimetric analysis revealed that these fibers are thermally stable until 270.48°C.     

A Simple Technique for Submicron Scale Patterning of Silver Using Visible Light Interference

A novel, one step and simple methodology for the fabrication of submicron scale silver patterns is demonstrated. The photosensitivity of an organic silver salt has been utilized for this purpose of fabrication. The silver-organometallic compound is converted to metallic silver selectively in the illuminated regions. Surface morphology was studied by scanning electron microscopy (SEM). Energy dispersion spectroscopy (EDS) shows the presence of silver in the developed film. X-ray photoelectron spectroscopy (XPS) confirms the formation of metallic silver. Feature sizes of the order of 200 nm have been achieved using this technique.     

Biocatalytic Synthesis of Two-Photon Active Resveratrol Oligomer

Resveratrol (3,5,4′ trihydroxy trans-stilbene) is a plant based phenolic compound. Enzymatic oligomerization of trans-resveratrol using horseradish peroxidase followed by characterization of the oligomer is presented. The oligomerization reaction was monitored using UV-Visible absorption and fluorescence spectroscopies. The oligomer exhibits strong two-photon-induced fluorescence. Computational modeling using spin-density calculations was performed to investigate the most probable reaction sites and the nature of products formed in the oligomerization process.     

Interaction studies of volatiles from jackfruit on α-phosphorene nanosheet—a DFT outlook

Structural Chemistry - The present report brings out the interaction between the black phospherene nanosheet and volatile organic compounds (VOCs) originating from jackfruit using the...