Radiation, optical, power flow, and electrical diagnostics at the Z facility: Layout and techniques utilized to operate in the harsh environment.

The Z machine is a current driver producing up to 30 MA in 100 ns that utilizes a wide range of diagnostics to assess accelerator performance and target behavior conduct experiments that use the Z target as a source of radiation or high pressures. We review the existing suite of diagnostic systems, including their locations and primary configurations. The diagnostics are grouped in the following categories: pulsed power diagnostics, x-ray power and energy, x-ray spectroscopy, x-ray imaging (including backlighting, power flow, and velocimetry), and nuclear detectors (including neutron activation). We will also briefly summarize the primary imaging detectors we use at Z: image plates, x-ray and visible film, microchannel plates, and the ultrafast x-ray imager. The Z shot produces a harsh environment that interferes with diagnostic operation and data retrieval. We term these detrimental processes "threats" of which only partial quantifications and precise sources are known. We summarize the threats and describe techniques utilized in many of the systems to reduce noise and backgrounds.

Modeling the one-dimensional imager of neutrons (ODIN) for neutron response functions at the Sandia Z facility.

The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 µm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-µm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 1012 deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting the resolution and response function. Finally, the experiment to determine CR-39 neutron sensitivity, with and without a high density polyethylene (n, p) converter, an edge spread function, and resolution will be discussed.

The concentration of isoflurane required to suppress learning depends on the type of learning.

BACKGROUND: Recent reports suggest that one type of learning, fear conditioning to context, requires more neural processing than a related type, fear conditioning to tone. To determine whether these types of learning were differentially affected by anesthesia, the authors applied isoflurane during the training phases of fear conditioning paradigms for freezing to context and freezing to tone. METHODS: The authors trained seven groups of eight rats to fear tone by administering a tone (conditioned stimulus) while breathing various concentrations of isoflurane from 0.00 to 0.75 minimum alveolar concentration (MAC; one concentration per group) separated by 0.12-MAC steps. On the succeeding day, and in the absence of isoflurane, the authors presented the tone (without shock) in a different context (different cage shape and odor) and measured the time each rat froze (became immobile). Six other groups of eight rats were trained to fear context by applying the shock in the absence of a tone but in the presence of environmental cues such as cage shape, texture, and odor. Fear to context was determined the succeeding day by returning the rat to the training cage (without shock) and measuring duration of freezing. Control groups (16 per group) received 0.75 MAC isoflurane but no foot shocks. Group scores were compared using analysis of variance, and the ED50 values for quantal responses of individual rats were calculated using logistic regression. RESULTS: Conditioning to context occurred at 0.00 and 0.13 MAC (P < 0.05 compared with unshocked control) but not 0.25 MAC; the ED50 was 0.25 +/- 0.03 MAC (mean +/- SEM). In contrast, conditioning to tone occurred at 0.48 MAC (P < 0.05) but not 0.62 MAC; the ED50 was 0.47 +/- 0.02 MAC (P < 0.01 for the difference between ED50 values). CONCLUSIONS: Suppression of fear conditioning to tone required approximately twice the isoflurane concentration that suppressed fear conditioning to context. Thus, the concentration of anesthetic required to suppress learning may depend on the neural substrates of learning. Our results suggest that isoflurane concentrations greater than 0.5 MAC may be needed to suppress both forms of fear conditioning.

The nonimmobilizer 1,2-dichlorohexafluorocyclobutane does not affect thermoregulation in the rat.

Inhaled and other anesthetics profoundly affect the central nervous system, causing amnesia, immobility in the face of noxious stimulation, and depression of thermoregulation. Nonimmobilizers, inhaled compounds whose lipophilicity suggests that they should be anesthetics, do not produce immobility, but they do cause amnesia. Their effects on thermoregulation were the subject of the present study. We gave eight rats isoflurane on one occasion and the nonimmobilizer 2N (1,2-dichlorolhexafluorocyclobutane) on another. We measured the effect of various concentrations of each compound on thermoregulation provoked by body cooling. The specific outcome was increased metabolism, as reflected in increased output of carbon dioxide. Isoflurane decreased the temperature threshold for such increases and the maximum response intensity, doing so in a concentration-dependent manner, whereas 2N had a minimal or no effect at any concentration up to 0.9 minimum alveolar concentration (estimated from its lipophilicity). Thus, 2N may be a useful tool for studies of the mechanisms mediating the thermoregulatory depression produced by anesthetics: 2N should not affect such a mechanism.

Microbiological quality of cooked chicken breasts containing commercially available shelf-life extenders.

Experiments were conducted to determine the effect of various shelf-life extenders on the aerobic plate counts (APC) of cooked chicken breast meat stored at refrigeration temperatures. Fresh chicken breast meat obtained from local grocers was injected with either 0.5, 1, 1.5, or 2% sodium lactate; 0.63, 1.25, 1.88, or 2.51 g/kg of a liquid smoke flavoring; 0.33, 0.66, 1, or 1.33% Per/Lac 1901, a fermented whey product; or 0.25, 0.5, 0.75, or 1% Alta 2341, a fermented corn syrup product. The samples were cooked at 85 C dry bulb, 77.8 C wet bulb to an internal temperature of 76.7 C. The cooked chicken breasts were cut into 20-g samples and aseptically placed into Ziploc bags. Initial APC were enumerated following 2-d incubation at 30 C. Additional stored samples (2 C) were subsequently evaluated for APC every week for 5 wk. Only one of the four ingredients, Alta 2341, significantly extended cooked breast meat shelf-life over that of the controls. Using Alta 2341 would be beneficial in extending the refrigerated shelf-life of cooked chicken breast meat up to 5 wk.

Fate of Listeria monocytogenes and pediococcal starter cultures during the manufacture of chicken summer sausage.

Two formulations of chicken summer sausages [100% hand deboned chicken meat (HDCM) and 85% HDCM and 15% chicken hearts (HDCM-CH)] were prepared with a nonpediocin-producing (PED-) Pediococcus acidilactici starter culture and inoculated with 10(4) or 10(7) cfu of a five-strain mixture of Listeria monocytogenes/g of batter. Sausages were fermented to pH 5.0 (11 h), cooked to an internal temperature of 66.5 C, cold-showered, and stored at 4 C (60 days) and 30 C (7 days). For both formulations and inoculation levels, L. monocytogenes populations decreased 1.3 to 1.8 log10 cfu/g by the end of fermentation. No L. monocytogenes organisms were recovered from sausages (by enrichment) following the cook and shower or storage at 4 or 30 C. In contrast, P. acidilactici increased .7 to 1.2 log10 cfu/g during fermentation, and < 10(2) cfu/g remained after the cook and shower and storage at 4 and 30 C. In a second set of experiments, sausages (HDCM) were prepared with a PED- or a pediocin-producing (PED+) P. acidilactici starter culture and challenged with the L. monocytogenes mixture (10(7) cfu/g). The PED- culture reduced numbers of L. monocytogenes 1.2 log10 cfu/g during fermentation, whereas L. monocytogenes numbers declined 2.6 log10 cfu/g in the presence of the PED+ culture. Although acid production by both starter cultures was equivalent, greater inhibition of L. monocytogenes by the PED+ compared with the PED- starter culture was attributed to in situ production of pediocin. Pediococcal starter cultures and proper cooking eliminated L. monocytogenes from sausages and established that PED+ cultures provide an additional hurdle against poultry-related listeriosis.

Genomic analysis of Pediococcus starter cultures used to control Listeria monocytogenes in turkey summer sausage.

The pulsed-field technique of clamped homogeneous electric field electrophoresis was employed to characterize and size genomic DNA of three pediocin-producing (Ped+) and two non-pediocin-producing (Ped-) strains of Pediococcus acidilactici. Comparison of genomic fingerprints obtained by digestion with the low-frequency-cleavage endonuclease AscI revealed identical restriction profiles for four of the five strains analyzed. Summation of results for 10 individually sized AscI fragments estimated the genome length to be 1,861 kb for the four strains (H, PAC1.0, PO2, and JBL1350) with identical fingerprints. Genomic analysis of the pediocin-sensitive, plasmid-free strain P. acidilactici LB42 with the unique fingerprint revealed nine AscI fragments and a genome length of about 2,133 kb. Ped- (JBL1350) and Ped+ (JBL1095) starter cultures (one each) were used to separately prepare turkey summer sausage coinoculated with a four-strain Listeria monocytogenes mixture (ca. 10(5) CFU/g). The starter cultures produced equivalent amounts of acid during fermentation, but counts of L. monocytogenes were reduced to a greater extent in the presence of the Ped+ starter culture (3.4 log10 unit decrease) than in the presence of the Ped- starter culture (0.9 log10 unit decrease). Although no listeriae were recovered from sausages following the cook/shower, appreciable pediocin activity was recovered from sausages prepared with the Ped+ strain for at least 60 days during storage at 4 degrees C. The results of this study revealed genomic similarities among pediococcal starter cultures and established that pediocins produced during fermentation provide an additional measure of safety against listerial proliferation in turkey summer sausage.

The effect of graded levels of corn oil and different fats on the performance of white pekin ducklings.

One-hundred-eighty male and female ducklings (90 of each sex) were fed isocaloric and isonitrogenous diets formulated to contain 0, 2, 4, 6, 8, or 10% corn oil in the starter (0 to 14 days), grower (14 to 35 days), and finisher (35 to 49 days) periods. Body weights of the ducklings were not different among treatments; however, feed consumption decreased significantly between 0 and 49 days of age (10.22, 9.78, 9.18, 9.00, 8.54, and 8.96 kg) as the level of dietary corn oil increased (0, 2, 4, 6, 8, and 10%, respectively). Regression analysis indicated a linear decrease in feed/gain (F/G) as corn oil increased in the diet. F/G (0 to 49 days) = 3.48 - .06 (% corn oil); r2 = .92. In a second experiment, isocaloric and isonitrogenous diets were formulated to contain 0% added fat (NF) or 4% corn oil (CO), peanut oil (PO), vegetable shortening (VS), lard (LD), or tallow (TL). The body weights of the ducklings were the same across treatments throughout the 49-day experiment. Ducklings fed 4% TL consumed significantly (P less than .05) less feed than those ducklings fed NF, PO, VS, or LD. Feed efficiency was not statistically different among the ducklings fed the six different diets.

Effects of sodium diacetate on the growth, feed efficiency, and intestinal microflora of broilers.

Three levels of sodium diacetate (.625, 1.25, and 3.75 g/kg diet) were incorporated into the diets of day-old broiler chicks. A control ration and a 20 mg/kg aureomycin ration were fed to additional groups of chicks. Each treatment contained 40 chickens at 3 weeks; the number was reduced to 20 chickens at 5 and 8 weeks. At 3 and 8 weeks of age, the large and small intestines of 5 chickens from each treatment were examined for selected microorganisms. Chick growth and feed efficiency were also recorded. The entire experiment was run twice, but in Trial 2 the lowest level of sodium diacetate treatment was replaced by a combination of sodium diacetate (.625 g/kg diet) and aureomycin (20 mg/kg diet). No improvement in the rate of growth was found in the sodium diacetate-treated groups, although additional weight gain was detected in aureomycin-fed groups at 2 weeks of age. Improved feed efficiency in the treated groups (sodium diacetate and aureomycin) was observed in both trials at 2 weeks and at 3 weeks of age in Trial 1. No feed efficiency effects were observed after that time. The sodium diacetate-fed groups showed an increased lactobacilli population in the small intestine along with a concurrent decrease in streptococci. The effect of sodium diacetate in reducing total coliforms in the large intestine was more obvious at 3 weeks than at 8 weeks. Aureomycin appeared to suppress the population of lactobacilli and total coliforms in this study. A combination of sodium diacetate and aureomycin failed to exhibit a synergistic effect either on the growth rate or on the intestinal microflora.

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) effects on serum and liver lipid levels in Gallus domesticus.

The food antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxy-toluene (BHT) were fed to chickens to determine their effect on lipid metabolism. BHA and BHT did not affect chicken growth, blood lipid levels or liver lipid levels when the birds were fed a normal ration. When a high fat, high cholesterol ration was fed, chickens developed increased levels of blood and liver lipids and experienced decreased growth rates. The addition of either antioxidant in the presence of a high fat high cholesterol diet maintained higher serum lipid levels and caused decreases in liver lipid levels.