Combat Capabilities Development Command Soldier Center

Recombinant DNA methods were used to create artificial proteins that undergo reversible gelation in response to changes in pH or temperature. The proteins consist of terminal leucine zipper domains flanking a central, flexible, water-soluble polyelectrolyte segment. Formation of coiled-coil aggregates of the terminal domains in near-neutral aqueous solutions triggers formation of a three-dimensional polymer network, with the polyelectrolyte segment retaining solvent and preventing precipitation of the chain. Dissociation of the coiled-coil aggregates through elevation of pH or temperature causes dissolution of the gel and a return to the viscous behavior that is characteristic of polymer solutions. The mild conditions under which gel formation can be controlled (near-neutral pH and near-ambient temperature) suggest that these materials have potential in bioengineering applications requiring encapsulation or controlled release of molecular and cellular species.

With their impressive individual properties, carbon nanotubes should form high-performance fibers. We explored the roles of nanotube length and structure, fiber density, and nanotube orientation in achieving optimum mechanical properties. We found that carbon nanotube fiber, spun directly and continuously from gas phase as an aerogel, combines high strength and high stiffness (axial elastic modulus), with an energy to breakage (toughness) considerably greater than that of any commercial high-strength fiber. Different levels of carbon nanotube orientation, fiber density, and mechanical properties can be achieved by drawing the aerogel at various winding rates. The mechanical data obtained demonstrate the considerable potential of carbon nanotube assemblies in the quest for maximal mechanical performance. The statistical aspects of the mechanical data reveal the deleterious effect of defects and indicate strategies for future work.

This article sets forth a simple cellulase assay procedure. Cellulose is variable in nature, insoluble and resistant to enzymatic attack. As a result there have been a bevy of bewildering cellulase assays published that yielded irrational results. Certain protocols focused on the rapidity of the assay while ignoring that only the most readily susceptible cellulose regions were being hydrolyzed. Other assays simplified the system by using modified soluble substrates and yielded results that bore no relationship to the real world hydrolysis of insoluble cellulose. In this study Mandels, Andreotti and Roche utilized a common substrate, Whatman filter paper. Hydrolysis of a 50 mg sample of the paper was followed to roughly 4% degradation, which circumvented the problems of attack of only the most susceptible zones. This common hydrolysis target range also resulted in some balance with regard to the interaction of the several cellulase components. The method was subsequently widely adopted.Douglas E Eveleigh.

The first use of electrospun nanofibrous membranes as highly responsive fluorescence quenching-based optical sensors for metal ions (Fe3+ and Hg2+) and 2,4-dinitrotoluene (DNT) is reported. A fluorescent polymer, poly(acrylic acid)−poly(pyrene methanol) (PAA−PM), was used as a sensing material. Optical chemical sensors were fabricated by electrospinning PAA−PM and thermally cross-linkable polyurethane latex mixture solutions. These sensors showed high sensitivities due to the high surface area-to-volume ratio of the nanofibrous membrane structures. The development of new approaches toward highly sensitive detection techniques remains a major challenge in the field of chemical sensing. It is widely accepted that the sensitivity of a sensor that detects analytes by interacting with molecules on the surface will increase with increasing surface area per unit mass. Therefore, considerable effort has been made to increase the surface area of the sensing interface in chemical sensors.1-5 However, these approaches either involve so-phisticated synthesis routes or cumbersome fabrication processes. Some of these techniques are also limited to

Spider silks are protein-based "biopolymer" filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to "biomimic" the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

Stress, a ubiquitous part of daily human life, has varied biological effects which are increasingly recognized as including modulation of commensal microorganisms residing in the gastrointestinal tract, the gut microbiota. In turn, the gut microbiota influences the host stress response and associated sequelae, thereby implicating the gut microbiota as an important mediator of host health. This narrative review aims to summarize evidence concerning the impact of psychological, environmental, and physical stressors on gut microbiota composition and function. The stressors reviewed include psychological stress, circadian disruption, sleep deprivation, environmental extremes (high altitude, heat, and cold), environmental pathogens, toxicants, pollutants, and noise, physical activity, and diet (nutrient composition and food restriction). Stressors were selected for their direct relevance to military personnel, a population that is commonly exposed to these stressors, often at extremes, and in combination. However, the selected stressors are also common, alone or in combination, in some civilian populations. Evidence from preclinical studies collectively indicates that the reviewed stressors alter the composition, function and metabolic activity of the gut microbiota, but that effects vary across stressors, and can include effects that may be beneficial or detrimental to host health. Translation of these findings to humans is largely lacking at present. This gap precludes concluding with certainty that transient or cumulative exposures to psychological, environmental, and physical stressors have any consistent, meaningful impact on the human gut microbiota. However, provocative preclinical evidence highlights a need for translational research aiming to elucidate the impact of stressors on the human gut microbiota, and how the gut microbiota can be manipulated, for example by using nutrition, to mitigate adverse stress responses.

A meta-analysis to mathematically summarize the effect of hot and cold temperature exposure on performance was completed. The results from 515 effect sizes calculated from 22 original studies suggest that hot and cold temperatures negatively impact performance on a wide range of cognitive-related tasks. More specifically, hot temperatures of 90 degrees F (32.22 degrees C) Web Bulb Globe Temperature Index or above and cold temperatures of 50 degrees F (10 degrees C) or less resulted in the greatest decrement in performance in comparison to neutral temperature conditions (14.88% decrement and 13.91% decrement, respectively). Furthermore, the duration of exposure to the experimental temperature, the duration of exposure to the experimental temperature prior to the task onset, the type of task and the duration of the task had differential effects on performance. The current results indicate that hot and cold temperature exposure have a negative impact on performance and that other variables (e.g., length of exposure to the temperature or task duration) may modify this relationship.

Abstract Waste cellulose was a suitable carbon source for cellulose production by Trichoderma viride . The enzyme can be produced in submerged fermentation using newspaper as a growth substrate. A variety of pure and complex cellulosic materials were hydrolyzed by culture filtrates. Saccharification of 5% slurries after 48 hr ranged from 2–92%. The rate and extent of hydrolysis was controlled by degree of crystallinity, particle size, and presence of impurities. Newspaper was used to evaluate methods for the pretreatment of substrate. The best pretreatment was ball milling which gave good size reduction, maximum bulk density, and maximum susceptibility. Hammer milling, fluid energy milling, colloid milling, or alkali treatments were less satisfactory. Dissolving cellulose in cuprammonium, or carbon disulfide (Viscose) and then reprecipitating gave a susceptible, but low bulk density product. However the susceptibility was lost if the substrate was dried. Because of costs, low bulk density, necessity of keep ing the substrate wet, and generation of chemical waste streams dissolving cellulose to increase reactivity does not seem a practical approach. Cellulose fractions separated from municipal trash or agricultural residues such as milled fibres from bovine manure are promising substrates for conversion.

A simple and rapid (< 60 s) nonstaining technique with 3% potassium hydroxide to determine Gram reactions was tested with 495 food-borne and waterborne bacteria and yeasts. In KOH, suspensions of gram-negative bacteria become viscous and string out. Gram-positive bacteria are not affected. There was 100% correlation between the KOH string test results and gram-positive and gram-negative strains.

In computation of fluid-structure interactions, we use mesh update methods consisting of mesh-moving and remeshing-as-needed. When the geometries are complex and the structural displacements are large, it becomes even more important that the mesh moving techniques are designed with the objective to reduce the frequency of remeshing. To that end, we present here mesh moving techniques where the motion of the nodes is governed by the equations of elasticity, with selective treatment of mesh deformation based on element sizes as well as deformation modes in terms of shape and volume changes. We also present results from application of these techniques to a set of two-dimensional test cases.

Following a brief review of prior work on fabric-based armor systems, the system effects that occur during the ballistic impact of woven fabric body armor materials are discussed from a conceptual framework developed to relate single yarn impact mechanics to fabric impact mechanics. The consequence of assembling yarns into single-ply fabric structures is discussed from this perspective. A steep strain gradient along yarns in the region of the transverse deflection of the fabric is related to the constraint imposed on them by neighboring yarns. Striking and residual velocity data, collected for single-ply fabric systems of Spectra®, Kevlar® 29, and nylon with various different yarn deniers and weave types, are used to establish the response of spaced armor systems. The system effects of assembling fabric plies into body armor systems are determined by comparing the response of spaced armor systems to actual multiple-ply systems. There is a pronounced decrease in energy absorption capacity for the Spectra and nylon systems; this deleterious effect is ascribed to increased transverse stresses and possible interference of the deflection characteristics of fabric plies by subsequent plies.

A bacteriophage cocktail (designated ECP-100) containing three Myoviridae phages lytic for Escherichia coli O157:H7 was examined for its ability to reduce experimental contamination of hard surfaces (glass coverslips and gypsum boards), tomato, spinach, broccoli, and ground beef by three virulent strains of the bacterium. The hard surfaces and foods contaminated by a mixture of three E. coli O157:H7 strains were treated with ECP-100 (test samples) or sterile phosphate-buffered saline buffer (control samples), and the efficacy of phage treatment was evaluated by comparing the number of viable E. coli organisms recovered from the test and control samples. Treatments (5 min) with the ECP-100 preparation containing three different concentrations of phages (10(10), 10(9), and 10(8) PFU/ml) resulted in statistically significant reductions (P = <0.05) of 99.99%, 98%, and 94%, respectively, in the number of E. coli O157:H7 organisms recovered from the glass coverslips. Similar treatments resulted in reductions of 100%, 95%, and 85%, respectively, in the number of E. coli O157:H7 organisms recovered from the gypsum board surfaces; the reductions caused by the two most concentrated phage preparations were statistically significant. Treatment with the least concentrated preparation that elicited significantly less contamination of the hard surfaces (i.e., 10(9) PFU/ml) also significantly reduced the number of viable E. coli O157:H7 organisms on the four food samples. The observed reductions ranged from 94% (at 120 +/- 4 h posttreatment of tomato samples) to 100% (at 24 +/- 4 h posttreatment of spinach samples). The data suggest that naturally occurring bacteriophages may be useful for reducing contamination of various hard surfaces, fruits, vegetables, and ground beef by E. coli O157:H7.

ABSTRACT Three studies were conducted to assess the effects of disconfirmed consumer expectations on food acceptability. In the first, disconfirmed expectations for the sensory attributes of an edible film had a negative effect on acceptability of the film. Greater disconfirmation resulted in lower acceptance and purchase intent. In the second study, written product information was used to establish three levels of expected acceptability and expected bitterness for a novel fruit beverage. Comparison of preexposure (expected) and postexposure (perceived) ratings of acceptability and bitterness supported an assimilation model of disconfirmation effects for conditions in which expectations of acceptability were high and expectations of bitterness were low. A contrast effect was observed for bitterness judgments when expectations of bitterness were high. Associative effects resulting from the expectation manipulation were observed on other sensory attributes. In the third study, expectations were manipulated to influence both direction (positive versus negative) and degree of disconfirmation for the acceptance of cola beverages. Results provided further support for an assimilation model of these effects.

It is experimentally shown that barium titanate glass microspheres with diameters (D) in the range 2–220 μm and with high refractive index (n ∼ 1.9–2.1) can be used for super-resolution imaging of liquid-immersed nanostructures. Using micron-scale microspheres, we demonstrate an ability to discern the shape of a pattern with a minimum feature size of ∼λ/7, where λ is the illumination wavelength. For spheres with D &amp;gt; 50 μm, the discernible feature sizes were found to increase to ∼λ/4. Detailed data on the resolution, magnification, and field-of-view are presented. This imaging technique can be used in biomedical microscopy, microfluidics, and nanophotonics applications.

ABSTRACT The most widely used scale for assessing food liking or disliking is the 9‐pt hedonic scale. Unfortunately, this affective scale suffers from problems related to unequal scale intervals and the underuse of end categories, which results in a reduced ability to differentiate among extremely well liked or extremely disliked foods. Magnitude estimation avoids these problems while enabling ratio statements to be made about the data. However, it does not provide absolute ratings of liking/disliking and can be difficult for some consumers to use. We report here on the development of a labeled affective magnitude scale (LAM) scale that has advantages over both the 9‐pt hedonic scale and magnitude estimation. Forty‐four semantic labels were scaled for their affective meaning by subjects using modulus‐free magnitude estimation. The geometric mean magnitude estimates obtained for each semantic label were used to construct a series of labeled affective magnitude scales by spacing the labels along a visual analogue scale according to their obtained semantic values. Reliability and sensitivity studies were conducted to assess the effects of alternative semantic and numeric labels. The results of these studies led to the choice of a scale format that uses verbal labels that are consistent with the 9‐pt hedonic scale. The labeled affective magnitude (LAM) scale was compared to the hedonic scale and magnitude estimation in several food preference and acceptability tests. The LAM was shown to have equal reliability and sensitivity to the hedonic scale, provided somewhat greater discrimination among highly liked foods, and resulted in data that were similar to magnitude estimation in terms of the obtained ratios among rated stimuli. The LAM scale was also judged by consumers to be as easy to use as the 9‐pt hedonic scale and significantly less difficult than magnitude estimation.

ABSTRACT Four experiments were conducted to assess the effect of food color on flavor identification of noncarbonated beverages and to assess the interactive effect of food color and flavor levels on the perceived flavor intensity and hedonic quality of beverages and cake. Results showed that color masking dramatically decreased flavor identification of fruit‐flavored beverages, while atypical colors induced incorrect flavor responses that were characteristically associated with the atypical color. In addition, the color level of beverages had significant effects on their overall acceptability, acceptability of color and of flavor, as well as on flavor intensity. The same results were shown with cake samples, with the exception that a significant interaction of color and flavor level was observed on overall acceptability. Correlational analysis on the subjective dimensions showed that the overall acceptability of both the beverage and cake products was more closely associated with ratings of flavor acceptability than with ratings of color acceptability. In addition, a test of the effect of colorant safety information showed that such information did not decrease any aspect of a product's acceptability.

Readers mentally simulate the objects and events described in narratives. One common assumption is that readers mentally embody an actor's perspective; alternatively, readers might mentally simulate events from an external "onlooker" perspective. Two experiments examined the role of pronouns in modulating a reader's adopted perspective when comprehending simple event sentences. Experiment 1 demonstrated that readers embody an actor's perspective when the pronoun you or I is used, but take an external perspective when he is used. Experiment 2, however, found that a short discourse context preceding the event sentence led readers to adopt an external perspective with the pronoun I. These experiments demonstrate that pronoun variation and discourse context mediate the degree of embodiment experienced during narrative comprehension: In all cases, readers mentally simulate objects and events, but they embody an actor's perspective only when directly addressed as the subject of a sentence.

We demonstrate here that large area periodic arrays of well-aligned carbon nanotubes can be fabricated inexpensively on Ni dots made by the process of self-assembly nanosphere lithography. These periodic arrays appear colorful due to their efficient reflection and diffraction of visible light. In addition, due to their honeycomb lattice structure, these arrays can act as photonic band gap crystals in the visible frequency range. In this report, we present the initial exploration of the optical properties of such arrays. Here we show that these potential 2D photonic band gap crystal arrays might find very important applications in optoelectronics.

Abstract No Abstrast.

Abstract Dragline silk from the spider, Nephila clavipes , was characterized by thermal analysis (TGA, DSC, DMA), computational modeling, scanning electron microscopy and by quasi‐static as well as high rates of strain. Thermal stability to about 230°C was observed by TGA, two transitions by DMA, −75°C, representative of localized motion in the amorphous domain, and a main chain motion associated with partial melt at 210°C. Tensile tests indicated average initial modulus, ultimate tensile strength and ultimate tensile strain of 22 GPa, 1.1 GPa and 9%, respectively. The corresponding properties of the best fibers tested were 60 GPa, 2.9 GPa and 11%, respectively. High strain rates (&gt;50,000%/sec) indicated similar mechanical properties to the average values indicated above. Microscopy showed compressive and tensile strains to failure of 34%. Computational modeling yielded a crystal modulus of 200 GPa.