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Context. Observations of intergalactic neutral hydrogen can provide a wealth of information about structure and galaxy formation, potentially tracing accretion and feedback processes on Mpc scales. Below a column density of $N_{\rm{HI}} \sim 10^{19}$cm-2, the “edge” or typical observational limit for H iemission from galaxies, simulations predict a cosmic web of extended emission and filamentary structures. Current observations of this regime are limited by telescope sensitivity, which will soon advance substantially.

We use cosmological hydrodynamic simulations with enriched galactic outflows to compare predictions for the galaxy mass-metallicity (M*− Z) with observations at z≈ 2 from Erb et al.(2006). With no outflows included galaxies are over-enriched, indicating that outflows are required not only to suppress star formation and enrich the IGM but also to lower galaxy metal content. The observed M*− Zslope is matched both in our model without winds as well as in our favored outflow model where the outflow velocity scales as the escape velocity, but is too steep in a model with constant outflow speeds. If outflows are too widespread at early times, the IGM out of which smaller galaxies form can become pre-polluted, resulting in a low-mass flattening of the M*− Zrelation that is inconsistent with data. Remarkably, the same momentum-driven wind model that provides the best agreement with IGM enrichment data also yields the best agreement with the z≈ 2 M*− Zrelation, showing the proper outflow scaling and strength to match the observed slope and amplitude. In this model, the M*− Zrelation evolves slowly from z= 6 → 2; an (admittedly uncertain) extrapolation to z = 0broadly matches local M*− Zobservations. Overall, the M*− Zrelation provides critical constraints on galactic outflow processes during the heyday of star formation in the Universe.

We use cosmological hydrodynamic simulations including galactic feedback based on observations of local starbursts to find a self-consistent evolutionary model capable of fitting the observations of the intergalactic metallicity history as traced by C ivbetween z= 6.0 → 1.5. Our main finding is that despite the relative invariance in the measurement of Ω(C iv) as well as the column density and linewidth distributions over this range, continual feedback from star formation-driven winds are able to reproduce the observations, while an early enrichment scenario where a majority of the metals are injected into the IGM at z> 6 is disfavored. The constancy of the C ivobservations results from a rising IGM metallicity content balanced by a declining C ivionization fraction due to a 1) decreasing physical densities, 2) increasing ionization background strength, and 3) metals becoming more shock-heated at lower redshift. Our models predict that ~20× more metals are injected into the IGM between z= 6 → 2 than at z> 6. We show that the median C ivabsorber at z= 2 traces metals injected 1 Gyr earlier indicating that the typical metals traced by C ivare neither from very early times nor from very recent feedback.

A method has been developed for ab initio determination of crystallographic phases. This technique, called forced coalescence phasing (FCP), is implemented on a computer and uses an automated iterative procedure that combines real space filtering with numerically seeded Fourier transforms to solve the crystallographic phase problem. This approach is fundamentally different from that of traditional direct methods of phasing, which rely on structure invariant probabilistic phase relationships. In FCP, the process begins with an appropriate set of atoms randomly distributed throughout the unit cell. In subsequent cycles of the program, these atoms undergo continual rearrangements ultimately forming the correct molecular structure(s) consistent with the observed x-ray data. In each cycle, the molecular rearrangement is directed by an electron density (Fourier) map calculated using specially formulated numerical seed coefficients that, along with the phase angles for the map, are derived from the arrangement of atoms in the preceding cycle. The method has been tested using actual x-ray data from three organic compounds. For each data set, 100 separate phase determination trials were conducted, each trial beginning with a different set of randomly generated starting phases. Correct phase sets were successfully determined in all of the trials with most trials requiring fewer than 50 cycles of the FCP program. In addition to its effectiveness in small molecule phase determination, FCP offers unexplored potential in the application of real-space methods to ab initio phasing of proteins and other macromolecule structures.

A radioimmunoassay (RIA) was developed for the quantification of caffeine in saliva. The mean salivary caffeine level for this sample of 40 full-term, AGA, healthy 1–2 day old human neonates was consistent with levels reported in previous studies. Salivary caffeine was significantly correlated with the number of state changes and startles observed during administration of the Brazelton Neonatal Behavior Assessment Scale. There was also a nonsignificant trend correlating salivary caffeine with visual orienting and consolability.

The aim of the present study was to enhance the pharmaceutical potential and oral bioavailability of piperine, which is the bioactive constituent of Piper nigrum, using the nanosuspension approach. Nanoprecipitation, which is a simple and reproducible process, was used for nanosuspension formulation. To prepare a pharmaceutical-grade nanosuspension with the required particle size, important formulation parameters (amount of plant extract, concentration of stabilizer, and antisolvent- to-solvent ratio) were optimized using the central composite design of response surface methodology. The optimized nanosuspension was characterized using scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and in vitro dissolution testing as well as by measuring the zeta potential. In vivo pharmacokinetic studies were conducted to determine the bioavailability of the prepared nanosuspension. Results of the optimization study indicated that 0.13% plant extract, 0.25% stabilizer, and an antisolvent-to-solvent ratio of 10.0 were the best parameters to obtain a homogeneous nanosuspension with the required particle size. The optimized nanosuspension demonstrated a mean particle size, polydispersity index, and zeta potential of 172.5 nm, 0.241, and -- 16.6mV, respectively. The results of the characterization studies illustrated that the nanosuspension was in the nanometer size range and had good surface morphology. The optimized nanosuspension showed a better dissolution rate and a 3.65-fold higher oral bioavailability for the P. nigrum nanosuspension than its coarse suspension. The present outcomes clearly demonstrated that to obtain an effective therapeutic potential, nanoformulation of medicinal plants is a better alternative than conventional dosage forms. [ABSTRACT FROM AUTHOR]