A study of the 144Sm(d,p) reaction at 19 MeV

The ¹⁴⁴Sm(d, p) reaction has been studied at an incident deuteron energy of 19 MeV using the injector-tandem accelerator and the multichannel magnetic speetrograph of the University of Oxford. Angular distributions have been measured for transitions to levels of ¹⁴⁵Sm up to an excitation energy of 3.2 MeV. Theoretical (d, p) distributions have been calculated using the program DWUCK. and orbital angular momentum transfers and spectroscopic factors have been deduced by comparing these calculations with the experimental data. The spectroscopic information derived from this study is more complete than that previously reported and many new assignments have been made. The level scheme of ¹⁴⁵Sm has been found to resemble closely the level schemes of the other N = 83 nuclei.     

Multiple melting transitions in fractions of partially isotactic poly(propylene oxide)

Three transitions are detected dilatometrically when partially isotactic poly(propylene oxide) melts. One transition, the temperature of which is independent of the crystallization temperature over a wide range below 60°C, is ascribed to the melting of lamellar crystallites which are limited in thickness by the average isotactic sequence length alone. The other two transitions, the temperatures of which vary with the crystallization temperature, are ascribed to the melting of lamellar crystallites with thickness determined predominantly by three- and two-dimensional primary nucleation acts. The theory of Flory is adapted and applied quantitatively to the melting points of three crystalline fractions of poly(propylene oxide), obtained from a polymer produced via the zinc diethyl and water catalyst system. This method leads to a thermodynamic melting point of isotactic poly(propylene oxide) near 82°C.     

Electroproduction of π0 mesons in the resonance region at q2=1.0 (GeV/c)2

Data are presented for the reaction ep → epπ⁰ at a nominal momentum transfer squared of 1.0 (GeV/c)². The data were obtained using an extracted electron beam from NINA and two magnetic spectrometers for coincidence detection of the electron and proton. Differential cross sections have been measured for isobar masses in the range 1.19–1.73 GeV/c².     

Lattice disorder and size-induced kondo behavior in CeAl2 and CePt(2+x)

When the size of CeAl2 and CePt(2+x) particles is reduced to the nanometer scale, antiferromagnetism is suppressed and Kondo behavior predominates, with the Kondo temperature T(K) either decreasing (CeAl2) or increasing (CePt(2+x)) relative to the bulk. Local structure measurements show that these nanoparticles are significantly distorted. While such distortions should strongly affect magnetic and electronic properties, we find they cannot explain the observed changes in T(K). Other size-induced changes to the electronic structure must, therefore, play a significant role.     

Template-guided organization of chromonic liquid crystals into micropatterned anisotropic organic solids

We have developed an approach to generate micropatterns of anisotropic organic materials which exploits the self-organization, driven by pi-stacking and hydrophobic interactions, of an ionic perylenebis(dicarboximide) in aqueous solutions.     

The role of problem representation and feature knowledge in algebraic equation-solving

Domain experts have two major advantages over novices with regard to problem solving: experts more accurately encode deep problem features (feature encoding) and demonstrate better conceptual understanding of critical problem features (feature knowledge). In the current study, we explore the relative contributions of encoding and knowledge of problem features (e.g., negative signs, the equals sign, variables) when beginning algebra students solve simple algebraic equations. Thirty-two students completed problems designed to measure feature encoding, feature knowledge and equation solving. Results indicate that though both feature encoding and feature knowledge were correlated with equation-solving success, only feature knowledge independently predicted success. These results have implications for the design of instruction in algebra, and suggest that helping students to develop feature knowledge within a meaningful conceptual context may improve both encoding and problem-solving performance.     

Total synthesis of (+/-)-mersicarpine

The first total synthesis of the indole alkaloid mersicarpine is reported. Key steps include a beta-dicarbonyl radical cyclization, as well as an oxidation of the benzopyrrole moiety to establish the masked 1,2-dicarbonyl functionality. An X-ray crystal structure and discussion of the 1H NMR behavior of the natural product are also presented.