Light-charged-particle evaporation from hot 31P nucleus at E*∼ 60 MeV

The inclusive energy spectra of light charged particles, such as, α, p, d and t, evaporated from the hot ³¹P nucleus at an excitation energy E ^*∼ 60 MeV, have been measured at various angles. The compound nucleus ³¹P has been populated using two different entrance channel configurations; i.e., ⁷Li (47 MeV) + ²⁴Mg and ¹⁹F (96 MeV) + ¹²C reactions, leading to the same excitation energy of the compound system. It has been observed that the spectra obtained in the ⁷Li (47 MeV) + ²⁴Mg reaction follow the standard statistical-model prediction with a spherical configuration of the compound nucleus. But, the spectra obtained in the ¹⁹F (96 MeV) + ¹²C reaction deviate from similar predictions of the statistical model both on higher- as well as on lower-energy sides. Considerable deformation was required to be incorporated in the calculation in order to reproduce the measured-energy spectra in this case. Dynamical trajectory model calculations were not found to play any significant role in explaining the differences in behaviour between the two cases under study. The observed discrepancy has been attributed to the difference in the angular-momentum distributions of the compound nuclei formed in the two reactions.     

X-ray K-absorption edge shifts in transition elements

It has been found that a striking correlation exists between the plasman energy in solids and the chemical shifts of the X-ray K-absorption edges of the transition elements Cr, Cu, Ni, Co, Zn and their compounds. Fairly good agreement between the calculated values of the plasmon energies and the observed values of the chemical shifts has been obtained.     

Electrokinetic studies of cotton. Part IV.: Role of water in influencing surface charge density of cotton in electrolyte solution

Summary The streaming potentials are measured at the interface between cotton chemisorbed with different crosslinking agents and different electrolyte solutions. Data were obtained as a function of concentration of electrolytes.The zeta potentials are found to decrease with increasing electrolyte concentration. The rate of change of zeta potential is much smaller than the theoretical values calculated from the different models of double layer. The discrepancy between the observed and theoretical values has been discussed.The surface charge density,, on cotton at the interface has been calculated and found to increase with the electrolyte concentration. This functional relationship between -C is explained from the consideration of the modification of the structure of water in the vicinity of the ion. The increase in surface charge density with the increase in electrolyte concentration is in the order KCl> NaI> NaBr> NaCl which is in the structure breaking capacity.

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Zusammenfassung Das Strömungspotential an den Grenzflächen der aus mit verschiedenen Vernetzungsmitteln chemisorbierter Baumwolle und verschiedenen elektrolytischen Lösungen entstehenden Systeme wurde in Abhängigkeit von der Konzentration der Elektrolyten bestimmt.Es wurde festgestellt, daß die Zeta-Potentiale mit zunehmender Konzentration der Elektrolyte abfallen. Die Abnahme der Zeta-Potentiale war viel kleiner als der aus verschiedenen Doppelschichtmodellen theoretisch errechnete Wert. Die Ursachen dieses Unterschiedes zwischen beobachteten und berechneten Werten wurden erläutert.Die Flächenladungsdichte () für Baumwolle an der Grenzfläche nimmt mit zunehmender Elektrolytkonzentration (C) zu. Die funktionelle Beziehung zwischen undC wurde auf der Basis der Modifikation des in Ionennähe befindlichen Wassers erklärt. Die Erhöhung der Flächenladungsdichte mit zunehmender Elektrolytkonzentration wächst in der Reihenfolge KCl > NaI > NaBr > NaCl, was mit der Strukturbruchfähigkeit der Ionen übereinstimmt.

     

Overlap contribution to57Fe3+ isomer shifts in fluorides and oxides

We have calculated the overlap contribution to the contact charge density at the⁵⁷Fe³⁺ site in fluoride and oxide lattices, FeF₃, CaFe₂O₄, CaBaFe₄O₈ and KFeO₂. The trend in isomer shifts in going from one lattice to another is explained in terms of the overlap effects. The experimental values of the change in isomer shift from lattice to lattice is used to obtain the change in nuclear size. The values of r/r _N are found to lie between –0.81×10^–4 and –1.56×10^–4.     

Stereocontrolled total synthesis of (--)-kaitocephalin

This paper describes the successful implementation of a stereocontrolled strategy for the total chemical synthesis of the pyrrolidine-based alkaloid (--)-kaitocephalin. This scalable synthetic route profits from the strategic utilization of substrate-controlled manipulations for the iterative installation of the requisite stereogenic centers. The key transformations include a diastereoselective modified Claisen condensation, a chemo- and diastereoselective reduction of a beta-keto ester, and the substrate-directed hydrogenation of a dehydroamino ester derivative. During the course of our investigations, an interesting stereoconvergent cyclization reaction was discovered for the efficient assembly of the kaitocephalin 2,2,5-trisubstituted pyrrolidine core.     

Evaluation of the Photo Electrode Degradation in Dye Sensitized Solar Cells

Russian Journal of Electrochemistry - The work reports on the interaction of the photo electrodes with the electrolytes and dyes since it is imperative to investigate the degradation behavior of...     

Ferrocenylketene and ferrocenyl-1,2-bisketenes: direct observation and reactivity measurements

[Structure: see text]. Ferrocenylketene (1) is calculated to be destabilized by 1.6 kcal/mol relative to phenylketene (10) by B3LYP isodesmic comparison to the corresponding alkenes. Ketene 1 generated by Wolff rearrangement in CH3CN is identified by the IR band at 2119 cm(-1) and has a rate constant for reaction with n-BuNH2 less than that for 10 by a factor of 5. 1,2-Bisferrocenyl-1,2-bisketene 18 and 1-ferrocenyl-2-trimethylsilyl-1,2-bisketene 21 were prepared by photochemical ring opening of the corresponding cyclobutenediones, and 18 undergoes rapid ring closure 67 times faster than the corresponding 1,2-diphenyl-1,2-bisketene, while bisketene 21 is longer lived than 18 by a factor of 3.2 x 10(4).     

Photoluminescence tuning and electro-optical memory in chiral nematic liquid crystals doped with silver nanoparticles

The photoluminescence spectra of chiral nematic liquid crystals doped with dodecanethiol-functionalised silver nanoparticles has been investigated. The peak intensity level of the photoluminescence in PL spectra was found to be consonant with the concentration (0.005–0.020 wt%) of silver nanoparticles. An uptrend of enhancement in the peak intensity was also recorded up till 0.015 wt% of dopant concentration, above which a fall in the peak intensity was recorded. A significant shift in the peak position was also detected with chiral dopant concentration. Electrically induced optical hysteresis was observed in the doped samples, which virtually vamooses at 0.020 wt% dopant concentration. Marked improvement in the attributes of silver-doped chiral nematic liquid crystal material under investigation has ensured vital appositeness of the composite for making memory and high-contrast display devices.