A cluster-variational investigation of static density waves in nuclear matter

A detailed comparison of the energy of the uniform phase and of phases exhibiting periodic density fluctuation is presented for extended nuclear systems. The short-range correlations are taken to be of Jastrow type and the calculations are carried through two-body cluster order. With semi-realistic central potentials containing hard cores, no energetic advantage of a non-uniform state is detected, either in symmetrical nuclear matter or in pure neutron matter. However, the analysis gives useful information on the conditions favoring an instability of the homogeneous phase and points to the essential role of the tensor force in the formation of spin-(isospin-) density waves.     

Measurement of the polarization in backward-angle π−p elastic scattering at 2.93 and 3.25 GeV/c

Polarization in π^?p elastic scattering, with emphasis over the backward region, has been measured at 2.93 and 3.25 GeV/c. We observe large changes in polarization compared with existing data above and below these energies. Our data may be useful in determining the properties of resonances and in understanding baryon exchanges.     

The structure of liquid bromine

The atom-atom correlation function for liquid bromine, derived from the X-ray diffraction studies reported in the preceding paper, is compared with the results of Monte Carlo computer simulations and reference site interaction model (RISM) calculations for various bromine-like model molecules. The models used included the two-centre Lennard-Jones interaction model, both by itself and with idealized point quadrupole and quadrupole-induced dipole interaction terms in the computer simulations, and two and three-centre hard-sphere models in RISM. None of these models lead to atom-atom correlation functions which are in good agreement with that obtained from experiment. This suggests that additional information about the interactions between bromine molecules will be needed before the structure of liquid bromine can be completely understood. Finally, by comparing the results of our computer simulations with RISM results for analogous models, we obtain some insight into the accuracy of the reference site interaction model.     

On-chip bioorthogonal chemistry enables immobilization of in situ modified nanoparticles and small molecules for label-free monitoring of protein binding and reaction kinetics

Efficient methods to immobilize small molecules under continuous-flow microfluidic conditions would greatly improve label-free molecular interaction studies using biosensor technology. At present, small-molecule immobilization chemistries require special conditions and in many cases must be performed outside the detector and microfluidic system where real-time monitoring is not possible. Here, we have developed and optimized a method for on-chip bioorthogonal chemistry that enables rapid, reversible immobilization of small molecules with control over orientation and immobilization density, and apply this technique to surface plasmon resonance (SPR) studies. Immobilized small molecules reverse the orientation of canonical SPR interaction studies, and also enable a variety of new SPR applications including on-chip assembly and interaction studies of multicomponent structures, such as functionalized nanoparticles, and measurement of bioorthogonal reaction rates. We use this approach to demonstrate that on-chip assembled functionalized nanoparticles show a preserved ability to interact with their target protein, and to measure rapid bioorthogonal reaction rates with k(2) > 10(3) M(-1) s(-1). This method offers multiple benefits for microfluidic biological applications, including rapid screening of targeted nanoparticles with vastly decreased nanoparticle synthetic requirements, robust immobilization chemistry in the presence of serum, and a continuous flow technique that mimics biologic contexts better than current methods used to measure bioorthogonal reaction kinetics such as NMR or UV-vis spectroscopy (e.g., stopped flow kinetics). Taken together, this approach constitutes a flexible and powerful technique for evaluating a wide variety of reactions and intermolecular interactions for in vitro or in vivo applications.     

A method to calculate the one‐electron reduction potentials for nitroaromatic compounds based on gas‐phase quantum mechanics

Nitroaromatic compounds (NACs) are widespread environmental contaminants, and the one‐electron reduction potential (E) is an important parameter used in modeling their environmental fate. We have identified a method that is both accurate and efficient to predict E values for NACs, using gas‐phase quantum mechanics (QM) calculations combined with empirical correlations. First, the adiabatic electron affinity (EA) at 0 K is calculated using the B98/MG3S method, and the predictions are scaled by a factor of 0.802 to account for systematic errors in the density functional calculations. Second, the E values are predicted from a linear correlation between E and EA. Using this method, E values were predicted with a mean absolute deviation from measured values of 0.021 V for the 14 NACs used to obtain the correlation and 0.029 V for six additional NACs. This represents a substantial improvement in accuracy over predictions by other QM methods, which are affected by large errors in solvation or aqueous‐phase calculations for some compounds. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010.     

Anomalies in a Lithium Niobate Stoichiometric Crystal in the Temperature Range 100–400 K

Optics and Spectroscopy - We show that the differences in the anomalous temperature behaviors of thermoluminescence and line intensities in the Raman spectra of congruent and stoichiometric lithium...     

Anionic cellulose beads for drug encapsulation and release

Cellulose beads were prepared from water-based solvent and oxidised by modified Anelli’s reaction at 20– $80\,^\circ \hbox {C}$ for 2–48 h (Fig. 1). The maximum amount of anionic groups (AGs) was $1.85\,\hbox {mmol}\,\hbox {g}^{-1}$ . The distribution of AGs was verified by absorption of cationic dyes and imaging with confocal fluorescent microscopy. Structural changes were studied spectroscopically and with electron microscopy. Oxidation of the beads drastically increased the swelling capacity of air-dried beads. Uptake of model drug was more than doubled in never-dried beads. This is due to the changes in pore size distribution, mainly opening and widening of the closed pores and narrow cavities. Release profiles of the drug were studied at physiological pH of 7.4 and showed a controlled release rate independently of the amount of the drug encapsulated and amount of AGs.