Sound localisation ability of soldiers wearing infantry ACH and PASGT helmets

Helmets provide soldiers with ballistic and fragmentation protection but impair auditory spatial processing. Missed auditory information can be fatal for a soldier; therefore, helmet design requires compromise between protection and optimal acoustics. Twelve soldiers localised two sound signals presented from six azimuth angles and three levels of elevation presented at two intensity levels and with three background noises. Each participant completed the task while wearing no helmet and with two U.S. Army infantry helmets – the Personnel Armor System for Ground Troops (PASGT) helmet and the Advanced Combat Helmet (ACH). Results showed a significant effect of helmet type on the size of both azimuth and elevation error. The effects of level, background noise, azimuth and elevation were found to be significant. There was no effect of sound signal type. As hypothesised, localisation accuracy was greatest when soldiers did not wear helmet, followed by the ACH. Performance was worst with the PASGT helmet.     

Characterization of α-carrageenan solution behavior by field-flow fractionation and multiangle light scattering

The salt mediated molecular conformation change of alpha (α)-carrageenan was studied in 0.1 M solutions of NaCl, NaI, and KCl. Asymmetric Field-Flow Fractionation with multiangle laser light scattering (AFFF/MALLS) detection was used to determine the average molecular weight, radius of gyration, and hydrodynamic radius which were in turn used to calculate the molecular density. In the presence of 0.1 M NaCl, an inert salt that does not promote gelation, α-carrageenan has a denser structure compared to κ-carrageenan of a similar molecular weight. A distinct and dramatic increase in the molecular weight (factor of 2) was observed for α-carrageenan in 0.1 M NaI compared to 0.1 M NaCl. This combined with only a slight change in the radius of gyration, suggests intermolecular interaction to a more compact structure (e.g., coaxial helices). A similar increase in molecular weight is observed in 0.1 M KCl, accompanied with an approximate 50% increase in the radius of gyration as well as an increase in polydispersity. This may also be attributed to intermolecular interaction with helix formation (coaxial or lateral) or may be due to K⁺ cations interacting with naturally occurring residual ι-carrageenan in the sample. As previously reported for other carrageenans the random coil to helix transition of α-carrageenan appears to be stabilized by K⁺ cation or I⁻ anion in an aqueous environment.     

Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging

Currently, magnetic iron oxide nanoparticles are the only nanosized magnetic resonance imaging (MRI) contrast agents approved for clinical use, yet commercial manufacturing of these agents has been limited or discontinued. Though there is still widespread demand for these particles both for clinical use and research, they are difficult to obtain commercially, and complicated syntheses make in-house preparation unfeasible for most biological research labs or clinics. To make commercial production viable and increase accessibility of these products, it is crucial to develop simple, rapid and reproducible preparations of biocompatible iron oxide nanoparticles. Here, we report a rapid, straightforward microwave-assisted synthesis of superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic method as either a two-step or single-step process. A striking benefit of these methods is the ability to obtain swift and consistent results without the necessity for air-, pH- or temperature-sensitive techniques; therefore, reaction times and complex manufacturing processes are greatly reduced as compared to conventional synthetic methods. This is a great benefit for cost-effective translation to commercial production. The nanoparticles are found to be superparamagnetic and exhibit properties consistent for use in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization.     

Numerous Applications of Fiber Optic Evanescent Wave Fourier Transform Infrared (FEW–FTIR) Spectroscopy for Surface and Subsurface Structural Analysis

A new infrared (IR) interferometric method has been developed in conjunction with low-loss, flexible optical fibers, sensors, and probes. This combination of fiber optical sensors and Fourier Transform (FT) spectrometers can be applied to many fields, including: (i) noninvasive medical diagnostics of cancer and other different diseases in vivo; (ii) minimally invasive bulk diagnostics of tissue; (iii) remote monitoring of tissue, chemical processes, and environment; (iv) surface analysis of polymers and other materials; (v) characterization of the quality of food, pharmacological products, cosmetics, paper, and other wood-related products, as well as (vi) agricultural, forensic, geological, mining, and archeological field measurements. In particular, our nondestructive, fast, compact, portable, remote, and highly sensitive diagnostics tools are very promising for subsurface analysis at the molecular level without sample preparation. For example, this technique is ideal for different types of soft porous foams, rough polymers, and rock surfaces. Such surfaces, as well as living tissue, are difficult to investigate by traditional FTIR methods. We present here FEW–FTIR spectra of polymers, banana and grapefruit peels, and living tissues detected directly at surfaces. In addition, results on the vibrational spectral analysis of normal and pathological skin tissue in the wavenumber region 850–4000cm^–1 are discussed.     

A compartment based population balance model for the prediction of steady and induction granule growth behavior in high shear wet granulation

This paper presents a predictive modeling approach of the high shear wet granulation process, quantifying the difference between the steady and induction granule growth behavior. The spatial heterogeneity in liquid binder distribution and shear rate is simulated using a compartmental population balance model. The granulator is divided into two compartments based on particle motion, which consists of a circulation compartment, and an impeller compartment. In the circulation compartment, a viscous dissipation dependent coalescence kernel is adapted for the aggregation process. In the impeller compartment a shear rate dependent aggregation kernel is implemented. The model was calibrated and validated using the dynamic evolution of granule mean size (d₅₀). The granulation dynamics are studied with respect to change in impeller speed, liquid to solid ratio, wet massing time, initial porosity, and binder viscosity. The transition from induction growth to steady growth regime with changing process conditions is demonstrated using the model. It is observed that the model captures the effect of process parameters and spatial heterogeneity on the dynamic evolution of d₅₀.     

Risk Planning and Management for the Panama Canal Expansion Program

In April 2006, the Panama Canal Authority formally proposed a major expansion of the canal to increase its capacity and make it more productive, safe, and efficient. This proposal included cost and schedule estimates for completing the expansion and was supported overwhelmingly by the citizens of Panama in an October 2006 public referendum. Given the conceptual level of design at the time of the proposal and the inherent uncertainty in a project of this magnitude at the early stages of engineering, a comprehensive risk analysis was performed to develop a contingency model for the total expansion program cost and schedule. This contingency model is based on a Monte Carlo simulation of the cost and schedule estimates, taking into account the most significant risks identified for the project. The resulting model provides contingency assessments for duration and total cost and sensitivity analysis of the risks; it also allows for multiple scenario planning and ultimately supports overall risk management. This paper presents a project case study that focuses on the contingency model development and the resulting risk management and contingency resolution processes.     

Directed Modulation of Protein Kinase C Isozyme Selectivity with Bisubstrate‐Based Inhibitors

Kinases present an attractive target for drug development, since they are involved in vital cellular processes and are implicated in a variety of diseases, such as cancer and diabetes. However, obtaining selectivity for a specific kinase over others is difficult since many current kinase inhibitors exclusively target the highly conserved kinase ATP binding domain. Previously, a microarray‐based strategy to discover so‐called bisubstrate‐based inhibitors that target the more specific peptide binding groove in addition to the ATP binding site was described. One attractive feature of this strategy is the opportunity to tune the selectivity of these inhibitors by systematically varying components. In an extension to this previous work, this study explores the potential of this guided selectivity modulation, leading to a series of inhibitors with different selectivity profiles against highly homologous protein kinase C (PKC) isozymes. Of the inhibitors studied, most exhibited improved potency and selectivity compared with their constituent parts. Furthermore, the selectivity was found to be tunable either through modification of the pseudosubstrate peptide (peptide binding groove) or the ATP‐competitive part (ATP binding site). In a number of cases, the selectivity of the construct could be predicted from the initial peptide substrate profiling experiment. Since this strategy is applicable to all kinase sets, it could be used to rapidly develop uniquely selective inhibitors.     

Gastrointestinal stability and bioavailability of (poly)phenolic compounds following ingestion of Concord grape juice by humans

The in vitro gastrointestinal stability of (poly)phenolic compounds in Concord grape juice was compared with recoveries in ileal fluid after the ingestion of the juice by ileostomists. Recoveries in ileal fluid indicated that 67% of hydroxycinnamate tartarate esters, and smaller percentages of the intake of other (poly)phenolic compounds, pass from the small intestine to the colon. The juice was also ingested by healthy subjects with an intact functioning colon. Peak plasma concentrations (C_max) ranged from 1.0 nmol/L for petunidin‐3‐O‐glucoside to 355 nmol/L for dihydrocoumaric acid. Urinary excretion, as an indicator of bioavailability, varied from 0.26% for total anthocyanins to 24% for metabolites of hydroxycinnamate tartarate esters. The C_max times of the anthocyanins indicated that their low level absorption occurred in the small intestine in contrast to hydroxycinnamate metabolites which were absorbed in both the small and the large intestine where the colonic microflora appeared responsible for hydrogenation of the hydroxycinnamate side chain. The bioavailability of the complex mixture of (poly)phenolic compounds in Concord grape juice, was very similar to that observed in previous studies when compounds were either fed individually or as major components in products containing a restricted spectrum of (poly)phenolic compounds.