Biocontrol of Salmonella Typhimurium in RTE foods with the virulent bacteriophage FO1-E2

Antimicrobial agents can be incorporated into edible films to provide microbiological stability, since films can be used as carriers of a variety of additives to extend product shelf life and reduce the risk of microbial growth on food surfaces. Addition of antimicrobial agents to edible films offers advantages such as the use of small antimicrobial concentrations and low diffusion rates. The aim of this study was to evaluate inhibition by vapor contact of Aspergillus niger and Penicillium digitatum by selected concentrations of Mexican oregano (Lippia berlandieri Schauer), cinnamon (Cinnamomum verum) or lemongrass (Cymbopogon citratus) essential oils (EOs) added to amaranth, chitosan, or starch edible films. Essential oils were characterized by gas chromatography-mass spectrometry (GC/MS) analysis. Amaranth, chitosan and starch edible films were formulated with essential oil concentrations of 0.00, 0.25, 0.50, 0.75, 1.00, 2.00, or 4.00%. Antifungal activity was evaluated by determining the mold radial growth on agar media inoculated with A. niger and P. digitatum after exposure to vapors arising from essential oils added to amaranth, chitosan or starch films using the inverted lid technique. The modified Gompertz model adequately described mold growth curves (mean coefficient of determination 0.991 ± 0.05). Chitosan films exhibited better antifungal effectiveness (inhibition of A. niger with 0.25% of Mexican oregano and cinnamon EO; inhibition of P. digitatum with 0.50% EOs) than amaranth films (2.00 and 4.00% of cinnamon and Mexican oregano EO were needed to inhibit the studied molds, respectively). For chitosan and amaranth films a significant increase (p<0.05) of lag phase was observed among film concentrations while a significant decrease (p<0.05) of maximum specific growth was determined. Chitosan edible films incorporating Mexican oregano or cinnamon essential oil could improve the quality of foods by the action of the volatile compounds on surface growth of molds.     

Submillimeter wave detector workshop

A brief report on the results of a workshop concerning submillimeter wave detection held September 34, 1985.     

High resolution crystal structure of a paired (Pax) class cooperative homeodomain dimer on DNA

The crystal structure of the paired homeodomain bound to DNA as a cooperative dimer has been determined to 2.0 A resolution. Direct contacts between each homeodomain and the DNA are similar to those described previously. In addition, an extensive network of water molecules mediates contacts between the recognition helix and the DNA major groove. Several symmetrical contacts between the two homeodomains underlie the cooperative interaction, and deformations in the DNA structure are necessary for the establishment of these contacts. Comparison with structures of homeodomains bound monomerically to DNA suggests that the binding of a single paired homeodomain can introduce these DNA distortions, thus preparing a template for the cooperative interaction with a second homeodomain. This study shows how the paired (Pax) class homeodomains have achieved cooperativity in DNA binding without the assistance of other domains, thereby enabling the recognition of target sequences that are long enough to ensure specificity.     

A contribution to the fractionation of polystyrene — poly-(alpha-methylstyrene) mixture using the methyl ethyl ketone — benzene/methanol system

Summary The fractionation of polystyrene, poly(alpha-methylstyrene) and physical mixture of these homopolymers in methyl ethyl ketone — benzene/methanol system was investigated. The solubility of poly(alpha-methylstyrene) increases with the decreasing of molecular weight and becomes similar to polystyrene at ¯M_w 29,000. Polystyrene and poly(alpha-methylstyrene) which precipitate simultaneously have different molecular weight and can be further separated by another method.     

The relative roles of avalanche multiplication and multiphoton absorption in laser-induced damage of dielectrics

The optical electric field strengths associated with pulsed laser exposures needed to produce conduction electron densities of 10¹⁸/cm³in several direct-gap alkali halides are calculated using three different models: a simplified avalanche model, the Keldysh formulation of multiphoton ionization, and a combination of the two. Numerical calculations are performed for crystalline NaCl, KCl, KBr, NaF, LiF, and CaF2at wavelengths of 1.064, 0.694, 0.532, and 0.355 μm, for nanosecond and picosecond pulse durations. The results are compared with available experimental data resulting in the following observations: the damage field strengths predicted by the avalanche model scatter around the experimentally measured values, but they always agree within a factor of approximately four. The electric field strengths required for breakdown solely from the simultaneous absorption of four or more photons are significantly larger than the experimental values or the predictions of the avalanche model. However, in NaCl, KCl, and KBr the electric fields necessary for damage due to four-photon absorption are slightly smaller than those needed for catastrophic avalanche multiplication, and are in significantly closer agreement with the experimentally measured damage thresholds. When the avalanche and multiphoton models are combined in a direct manner the resulting thresholds are close to the smaller of the two previously calculated thresholds, and are in reasonable agreement with the experimental data with respect to their dependence on laser frequency and pulse duration.     

Aided and automatic target recognition based upon sensory inputsfrom image forming systems

This paper systematically reviews 10 years of research that several Army Laboratories conducted in object recognition algorithms, processors, and evaluation techniques. In the military, object recognition is applied to the discrimination of military targets, ranging from human-aided to autonomous operations, and is called automatic target recognition (ATR). The research described here has been concentrated in human-aided target recognition applications, but some attention has been paid to automatic processes. Definitions and performance metrics that have been developed are described along with performance data showing the present state-of-the-art. The effects of signal-to-noise and clutter parameters are indicated in the data. Multisensor fusion and model-based algorithms are discussed as the latest techniques under consideration by the military research community. The results demonstrate that useful performance can be achieved, and tools are evolving to understand and improve the performance under real-world conditions. The referenced research strongly indicates the need for the development of image science, as described in the paper, to support the theoretical underpinnings of ATR     

Changes in Thy-1 antigen immunoreactivity in the rat retina during pre- and postnatal development

This paper reports the findings of a survey of a group of general dental practitioners (GDPs) from one region of the United Kingdom. The practitioners were asked to complete a questionnaire investigating their approach to the restoration of root-filled teeth. A high response rate was achieved and the replies indicated that most practitioners restore teeth within 1 month of completing the root filling. Nonprecious cast alloys cores were popular as was amalgam for core build-ups. Most practitioners opted for a post which was two-thirds the length of the root and zinc phosphate was the most popular luting material. Almost one-quarter of respondents believed that a root is strengthened by a post retained restoration and a similar number have never attended a postgraduate meeting on the subject of the restoration of root-filled teeth.