bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of magnetic field on the stability region of the bipolaron in high‐Tc superconductors with the Van Hove scenario
Authors: Bouayad M. , El Amrani B. , Fliyou M. , Chaouch M.
Published: August 2006

The properties of polarons and bipolarons are studied by the variational method taking into account the density of state for Van Hove singularity (V.H.S) in two‐dimension (2D) in the presence of a perpendicular magnetic field. It should be noticed that the bipolaron stability region is relatively sensitive to the application of a magnetic field. In 2D, for ωc = 0.8 the value of αc = 1 is compared to αc = 1.6 for ωc = 0. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic effects in a powder oriented YBCO sample using a three axes magnetometer
Authors: Boudissa M. , Halimi R. , Senoussi S.
Published: August 2006

To measure the components of the magnetization vector along the XYZ directions of a reference frame, in the superconducting materials, we have conceived a three axes magnetometer, with a detection system equipped with three series of pick‐up coils with axes parallel to the three directions X,Y, and Z. We describe in this paper the details of the design and the method of measurement, with some results obtained by magnetic measurements on samples of oriented YBCO powder, with size of the grains between 20 µm and 40 µm, for values of the angle θ between the magnetic field H and the c‐axis, between 0° and 90° and for values of fields up to 12 T. The direct measurement of the Z and the XY components of the irreversible magnetization vector, Mirr, allowed us to observe the twin effect (channeling) on the vortex pinning observed by many authors, the evolution of the magnetization vector and to measure with a high accuracy the anisotropy factor of our samples. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of the noise voltage in high‐Tc superconducting thin films
Authors: Labrag A. , Bghour M. , Abaragh A. , Bouaaddi A. , Ramzi A. , Taoufik A. , Senoussi S. , Tirbiyine A.
Published: August 2006

We measured the noise spectral density SV variations of YBa2Cu3O7–δ films in a large range of frequencies f 0.1‐1000 Hz, temperature T and under the effect of a magnetic field up to 14 T. in order to clarify the origin of the noise observed in thin films deposed by the laser ablation method on the surface (001) of SrTiO3 substrate, the noise power spectral density S(f,T) of the noise variations versus temperature and frequency is presented in Fig. 3 for H = 14 T parallel to the ab plane, I = 3 nA. We can observe from this result that the noise spectral density SV(T) shows a marked enhancement near Tc the temperature superconducting transition. Our results suggested that the main source for the noise in the mixed state is the thermally activated vortex motion in the high‐Tc superconducting thin films. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of Zn doping on YBaCuO superconductor
Authors: Mahtali M. , Chamekh S. , Boucherka T. , Bouabellou A.
Published: August 2006

In this work we present a study of Zn impurity effects on the YBa2Cu3O7–δ high Tc superconducting ceramics prepared by the solid state reaction method. X‐ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA) techniques, and resistivity measurements are used to characterize the YBa(Cu1–xZnx)3O7–δ samples. The obtained results show that, for example, the value of the transition critical temperature is decreasing up to 80 K caused by the substitution of Zn for Cu in the interval 0 ≤ x ≤ 0.01. Also, the peritectic transformation of superconducting phase undergoes a displacement to lower temperatures compared with pure YBaCuO. On the basis of the obtained results, the effects of Zn doping on the structural and electronic properties are explained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of the magnetization loops of high‐Tc superconductors
Authors: Abaragh A. , Taoufik A. , Ramzi A. , Senoussi S. , Labrag A. , Bghour M. , Bouaaddi A. , Tirbiyine A.
Published: August 2006

We have investigated the irreversibility magnetic field and the critical current density of the high temperature superconductor YBa2Cu3O7–δ single crystal. Vibrating sample magnetometer (V.S.M.) method was used for these measurements. Magnetization hysteresis loops scale and shape are strongly dependent on the temperature values and the angle θ between the direction of the applied magnetic field and c‐axis. For the large single crystals at very low temperature the loops present several flux jumps “saw‐tooth” and we observe the second peak “fish‐tail” for high temperature values but not with applied magnetic field perpendicular to the ab ‐planes. Beyond θ = 30°, the irreversibility field Hirr increases deviates from different temperature values. The variation of the critical current density Jc with applied magnetic field parallel to c‐axis for different temperatures was studied. Here, Jc is an effective critical current density deduced from the measured magnetization by the Bean formula. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mountain hydrology of the western United States
Authors: Bales Roger C. , Molotch Noah P. , Painter Thomas H. , Dettinger Michael D. , Rice Robert , Dozier Jeff
Published: August 2006

Climate change and climate variability, population growth, and land use change drive the need for new hydrologic knowledge and understanding. In the mountainous West and other similar areas worldwide, three pressing hydrologic needs stand out: first, to better understand the processes controlling the partitioning of energy and water fluxes within and out from these systems; second, to better understand feedbacks between hydrological fluxes and biogeochemical and ecological processes; and, third, to enhance our physical and empirical understanding with integrated measurement strategies and information systems. We envision an integrative approach to monitoring, modeling, and sensing the mountain environment that will improve understanding and prediction of hydrologic fluxes and processes. Here extensive monitoring of energy fluxes and hydrologic states are needed to supplement existing measurements, which are largely limited to streamflow and snow water equivalent. Ground‐based observing systems must be explicitly designed for integration with remotely sensed data and for scaling up to basins and whole ranges.
An improved analytical solution for interface upconing around a well
Authors: Nordbotten Jan M. , Celia Michael A.
Published: August 2006

Interface models of two‐phase flow to a well usually apply vertical equilibrium assumptions to capture the vertical pressure variation in the two fluids. When large gradients in interface height occur, this leads to poor approximations. To deal with large‐gradient interfaces, a variety of correction factors have been proposed on the basis of single‐phase flow analogies. Herein we propose to include the effects of vertical flow directly through a nonlinear vertical pressure variation. This more complex formulation captures significantly more of the flow dynamics in the near‐well region.
Nonlinear evolution of thermal self‐focusing instability in ionospheric modifications at high latitudes: Aspect angle dependence
Authors: Gondarenko N. A. , Ossakow S. L. , Milikh G. M.
Published: August 2006

A first simulation study for the nonlinear evolution of the thermal self‐focusing instability at high latitudes to examine the dependence of the nonlinear effects on the direction of the heater beam is presented. We demonstrate that due to a local heating of the F region anisotropic plasma, field‐aligned bunch‐scale structures with a strong enhancement of the electron temperature and negative density perturbations inside these structures are developed. The electron temperature increases up to more than 200% of the background when the incident beam is near the magnetic zenith, as observed in the heating experiment at the EISCAT high‐latitude facility (Rietveld et al., 2003). The values of the simulated electron temperature enhancements show a strong dependence on the heater beam direction that is in very good agreement with the EISCAT observations.
Tsunami travel time prediction using neural networks
Authors: Barman Rahul , Prasad Kumar B. , Pandey P. C. , Dube S. K.
Published: August 2006

The present work reports the development of a nonlinear technique based on artificial neural network (ANN) for prediction of tsunami travel time in the Indian Ocean. The expected times of arrival (ETA) computation involved 250 representative coastal stations encompassing 35 countries. A travel time model is developed using ANN approach. The ANN model uses non‐linear regression where a Multi‐layer Perceptron (MLP) is used to tackle the non‐linearity in the computed ETA. The back‐propagation feed forward type network is used for training the system using the resilient back‐propagation algorithm. The model demonstrates a high degree of correlation, proving its robustness in development of a real‐time tsunami warning system for Indian Ocean.
Double peak‐flood current asymmetry in a shallow‐water‐constituent dominated embayment with a macro‐tidal flat
Authors: Byun Do‐Seong , Cho Yang‐Ki
Published: August 2006

Tide and tidal current distortions were examined in Hampyung Embayment, a shallow, semidiurnal tide‐dominated bay with large tidal flats, via in situ monitoring. Harmonic analyses reveal that the shallow‐water constituents of the tides and tidal currents are strong in this restricted setting relative to on the open coast. In particular, the amplitudes of the shallow‐water currents constituents (M4, MS4, M6, 2MS6) are three times greater than those of the diurnal constituents (K1, O1). The quarter‐diurnal (M4 + MS4) and sexta‐diurnal (M6 + 2MS6) current amplitudes account for >35% and >17% of the semi‐diurnal current (M2 + S2) amplitudes, which account for >42% of total amplitude. The MS4 current amplitude is as important as that of the M4 amplitude in the middle of the bay. Such strong generation of shallow‐water velocity constituents induced by non‐linear processes leads to an ebb‐dominated tidal regime with double‐flood current‐velocity peaks.
Anomalous monsoonal activity in central Arizona, USA
Authors: Diem Jeremy E.
Published: August 2006

Published research has suggested that urban and agricultural activities in central Arizona may be enhancing monsoonal precipitation in the region; therefore, this study employed cloud‐to‐ground lightning data and topographic data to reveal spatially anomalous zones of lightning activity in central Arizona. A multiple linear regression model with topographic variables as predictors explained 85% of the variance in gridded lightning‐flash counts. Clustering of large positive residuals of lightning flashes existed between 40 km and 100 km north/northeast of urbanized Phoenix. Observed lightning flashes in this zone were ∼40% more frequent than lightning flashes predicted by the model. Two plausible causes of the enhanced lightning activity are intensified convective storms due to Phoenix‐derived water vapor and altered microphysical processes in storm clouds due to Phoenix‐derived atmospheric pollution. It is possible that the positive‐anomaly zone also had enhanced rainfall.
An analysis of the mechanisms of North American pollutant transport to the central North Atlantic lower free troposphere
Authors: Owen R. C. , Cooper O. R. , Stohl A. , Honrath R. E.
Published: August 2006

We use the FLEXPART Lagrangian particle dispersion model and observations from the PICO‐NARE station to identify and analyze the transport of North American anthropogenic emissions to the central North Atlantic lower free troposphere (FT) during July 2003. FLEXPART adequately captured the occurrence of CO transport events, simulating all but 1 of the 16 observed events while producing only 3 events not observed. Low‐level transport (below 3 km) was responsible for most events. Three case studies of this type are presented. Export from the North American boundary layer in these events was the result of eastward advection over the ocean or transport in a weak warm conveyor belt airflow. Once over the ocean, transport was governed by geostrophic winds between the Azores/Bermuda High (ABH) and transient northerly lows. The varying locations of the ABH and northerly lows determine the pathway of this type of event. As a result, other events similar to those analyzed here reach Europe. Transported below 3 km, these events were observed in the lower FT over the Azores and were accompanied by O3 enhancements. Thus the lower marine FT may provide a transport environment significantly different from the marine boundary layer, where O3 destruction is believed to dominate. In the fourth case study, North American emissions were lofted to 6–8 km in a warm conveyor belt, captured for 2 days in the midtropospheric circulation of the associated cyclone, and then entrained in the same cyclone's dry airstream and transported down to the Azores.
Illustration of transition path theory on a collection of simple examples
Authors: Metzner Philipp , Schütte Christof , Vanden-Eijnden Eric
Published: August 2006

Transition path theory (TPT) has been recently introduced as a theoretical framework to describe the reaction pathways of rare events between long lived states in complex systems. TPT gives detailed statistical information about the reactive trajectories involved in these rare events, which are beyond the realm of transition state theory or transition path sampling. In this paper the TPT approach is outlined, its distinction from other approaches is discussed, and, most importantly, the main insights and objects provided by TPT are illustrated in detail via a series of low dimensional test problems.
Effect of dipolar moments in domain sizes of lipid bilayers and monolayers
Authors: Travesset A.
Published: August 2006

Lipid domains are found in systems such as multicomponent bilayer membranes and single component monolayers at the air-water interface. It was shown by Keller et al. [J. Phys. Chem. 91, 6417 (1987)] that in monolayers, the size of the domains results from balancing the line tension, which favors the formation of a large single circular domain, against the electrostatic cost of assembling the dipolar moments of the lipids. In this paper, we present an exact analytical expression for the electric potential, ion distribution, and electrostatic free energy for different problems consisting of three different slabs with different dielectric constants and Debye lengths, with a circular homogeneous dipolar density in the middle slab. From these solutions, we extend the calculation of domain sizes for monolayers to include the effects of finite ionic strength, dielectric discontinuities (or image charges), and the polarizability of the dipoles and further generalize the calculations to account for domains in lipid bilayers. In monolayers, the size of the domains is dependent on the different dielectric constants but independent of ionic strength. In asymmetric bilayers, where the inner and outer leaflets have different dipolar densities, domains show a strong size dependence with ionic strength, with molecular-sized domains that grow to macroscopic phase separation with increasing ionic strength. We discuss the implications of the results for experiments and briefly consider their relation to other two dimensional systems such as Wigner crystals or heteroepitaxial growth.
Genome sequence of
Synechococcus
CC9311: Insights into adaptation to a coastal environment
Authors: Palenik Brian , Ren Qinghu , Dupont Chris L. , Myers Garry S. , Heidelberg John F. , Badger Jonathan H. , Madupu Ramana , Nelson William C. , Brinkac Lauren M. , Dodson Robert J. , Durkin A. Scott , Daugherty Sean C. , Sullivan Stephen A. , Khouri Hoda , Mohamoud Yasmin , Halpin Rebecca , Paulsen Ian T.
Published: August 2006

Coastal aquatic environments are typically more highly productive and dynamic than open ocean ones. Despite these differences, cyanobacteria from the genus
Synechococcus
are important primary producers in both types of ecosystems. We have found that the genome of a coastal cyanobacterium,
Synechococcus
sp. strain CC9311, has significant differences from an open ocean strain,
Synechococcus
sp. strain WH8102, and these are consistent with the differences between their respective environments. CC9311 has a greater capacity to sense and respond to changes in its (coastal) environment. It has a much larger capacity to transport, store, use, or export metals, especially iron and copper. In contrast, phosphate acquisition seems less important, consistent with the higher concentration of phosphate in coastal environments. CC9311 is predicted to have differences in its outer membrane lipopolysaccharide, and this may be characteristic of the speciation of some cyanobacterial groups. In addition, the types of potentially horizontally transferred genes are markedly different between the coastal and open ocean genomes and suggest a more prominent role for phages in horizontal gene transfer in oligotrophic environments.
The
Salmonella
effector protein PipB2 is a linker for kinesin-1
Authors: Henry Thomas , Couillault Carole , Rockenfeller Patrick , Boucrot Emmanuel , Dumont Audrey , Schroeder Nina , Hermant Aurélie , Knodler Leigh A. , Lecine Patrick , Steele-Mortimer Olivia , Borg Jean-Paul , Gorvel Jean-Pierre , Méresse Stéphane
Published: August 2006

Understanding the mechanisms of
Salmonella
virulence is an important challenge. The capacity of this intracellular bacterial pathogen to cause diseases depends on the expression of virulence factors including the second type III secretion system (TTSS-2), which is used to translocate into the eukaryotic cytosol a set of effector proteins that divert the biology of the host cell and shape the bacterial replicative niche. Yet little is known about the eukaryotic functions affected by individual
Salmonella
effectors. Here we report that the TTSS-2 effector PipB2 interacts with the kinesin light chain, a subunit of the kinesin-1 motor complex that drives anterograde transport along microtubules. Translocation of PipB2 is both necessary and sufficient for the recruitment of kinesin-1 to the membrane of the
Salmonella
-containing vacuole.
In vivo
, PipB2 contributes to the attenuation of
Salmonella
mutant strains in mice. Taken together, our data indicate that the TTSS-2-mediated fine-tuning of kinesin-1 activity associated with the bacterial vacuole is crucial for the virulence of
Salmonella
.
Hormonal and Stress Induction of the Gene Encoding Common Bean Acetyl-Coenzyme A Carboxylase
Authors: Figueroa-Balderas Rosa Elia , García-Ponce Berenice , Rocha-Sosa Mario
Published: August 2006

Regulation of the cytosolic acetyl-coenzyme A carboxylase (ACCase) gene promoter from common bean (Phaseolus vulgaris) was studied in transgenic Arabidopsis (Arabidopsis thaliana) plants using a β-glucuronidase (GUS) reporter gene fusion (PvACCase∷GUS). Under normal growth conditions, GUS was expressed in hydathodes, stipules, trichome bases, flowers, pollen, and embryos. In roots, expression was observed in the tip, elongation zone, hypocotyl-root transition zone, and lateral root primordia. The PvACCase promoter was induced by wounding, Pseudomonas syringae infection, hydrogen peroxide, jasmonic acid (JA), ethylene, or auxin treatment. Analysis of PvACCase∷GUS expression in JA and ethylene mutants (coronatine insensitive1-1 [coi1-1], ethylene resistant1-1 [etr1-1], coi1-1/etr1-1) suggests that neither JA nor ethylene perception participates in the activation of this gene in response to wounding, although each of these independent signaling pathways is sufficient for pathogen or hydrogen peroxide-induced PvACCase gene expression. We propose a model involving different pathways of PvACCase gene activation in response to stress.
Rapid Metabolism of Glucose Detected with FRET Glucose Nanosensors in Epidermal Cells and Intact Roots of Arabidopsis RNA-Silencing Mutants
Authors: Deuschle Karen , Chaudhuri Bhavna , Okumoto Sakiko , Lager Ida , Lalonde Sylvie , Frommer Wolf B.
Published: August 2006

Genetically encoded glucose nanosensors have been used to measure steady state glucose levels in mammalian cytosol, nuclei, and endoplasmic reticulum. Unfortunately, the same nanosensors in Arabidopsis thaliana transformants manifested transgene silencing and undetectable fluorescence resonance energy transfer changes. Expressing nanosensors in sgs3 and rdr6 transgene silencing mutants eliminated silencing and resulted in high fluorescence levels. To measure glucose changes over a wide range (nanomolar to millimolar), nanosensors with higher signal-to-noise ratios were expressed in these mutants. Perfusion of leaf epidermis with glucose led to concentration-dependent ratio changes for nanosensors with in vitro K  d values of 600 μM (FLIPglu-600μΔ13) and 3.2 mM (FLIPglu-3.2mΔ13), but one with 170 nM K  d (FLIPglu-170nΔ13) showed no response. In intact roots, FLIPglu-3.2mΔ13 gave no response, whereas FLIPglu-600μΔ13, FLIPglu-2μΔ13, and FLIPglu-170nΔ13 all responded to glucose. These results demonstrate that cytosolic steady state glucose levels depend on external supply in both leaves and roots, but under the conditions tested they are lower in root versus epidermal and guard cells. Without photosynthesis and external supply, cytosolic glucose can decrease to <90 nM in root cells. Thus, observed gradients are steeper than expected, and steady state levels do not appear subject to tight homeostatic control. Nanosensor-expressing plants can be used to assess glucose flux differences between cells, invertase-mediated sucrose hydrolysis in vivo, delivery of assimilates to roots, and glucose flux in mutants affected in sugar transport, metabolism, and signaling.
Lipolytic Activity of Microorganisms at Low and Intermediate Temperatures. II. Fatty Acids Released As Determined by Gas Chromatography
Authors: ALFORD JOHN A. , ELLIOTT L. E. , HORNSTEIN IRWIN , CROWE P. F.
Published: August 2006

Determination was made of the types and quantities of fatty acids released from lard, tallow, corn oil, and coconut oil by lipases from psychrophilic strains of Pseudomonas. The fatty acids were measured by gas chromatography. The rate of fatty acid liberation fell off sharply after the first few hours, but the ratios of the types of fatty acids were not affected until after 24 hours. Additional evidence is presented that much of the palmitic acid in lard is esterified at the beta position. Also discussed is the possible effect of differences in rate of lipolysis of fatty acids from natural substrates on interpretation of their degree of randomness, as measured by enzyme specificity.
The Nutritive Value of Maine Sardines.a
Authors: PROCTOR B. E. , MILLER S. A. , GOLDBLITH S. A. , WICK E. L. , PARTSER E. R. , SAPERS G. M. , SOLBERG M.
Published: August 2006

Maine sardines, processed by steaming or deep‐fat frying, were evaluated in terms of a number of nutrients. The product is a good source of a number of nutrients, including protein, unsaturated fatty acids, fluorine, and calcium. Some indication was found of an exchange between the packing oil and sardine lipid. The sample processed by deep‐fat frying had a slightly increased fat concentration and a concomitant decrease in water.
Maple Sirup. XVI. Isolation and Identification of Compounds Contributing to the Flavor of Maple Sirupa
Authors: UNDERWOOD J. C. , WILLITS C. O. , LENTO HARRY G.
Published: August 2006

A major portion of the flavor was isolated from maple sirup by extraction with chloroform. From this was separated several pure crystalline compounds and several impure materials. Vanillin and syringaldehyde were definitely identified. These are compounds that could come from precursors in the decomposition of lignin, and this possible source of maple flavor is being investigated.
Spectrophotometric Determination of Sorbic Acid in Apple Cidera
Authors: HARRINGTON W. O. , JAHN ANNE S. , HILLS CLAUDE H.
Published: August 2006

An improved method for measuring sorbic acid in cider is based on dilution of the sample and direct ultraviolet readings at 262 mμ This method was compared with the distillation method for sorbic acid usually applied to cider. The latter method produced ultraviolet‐absorbant materials that interfered with sorbic acid determinations and were shown to he affected by the sugar content of the cider and the distillation techniques. The ultraviolet‐interfering materials in cider distillates have absorption peaks and chemical properties similar to those of 5‐hydroxymethylfurfural.
An Ion‐Exchange Study of the Free Amino Acids in the Juices of Six Varieties of Citrusa
Authors: CLEMENTS ROBERT L. , LELAND HARRY V.
Published: August 2006

Free amino acids were determined in the juices of mature Valencia and Washington navel oranges, Eureka and Lisbon lemons, Dancy taugerines, and Marsh grapefruit. Twelve amino acids and ammonia were identified and measured quantitatively. Eleven unidentified ninhydrin‐positive compounds were also'detected. Alanine, asparagine, aspartic acid, glutamic acid, proline, set‐me, γ‐aminobutyric acid, and arginine occurred in substantial amounts in all fruits. Proline was the most prominent amino acid in every fruit except the grapefruit, hut appeared in especially high concentrations in the Valencia orange. Aspartic acid predominated in the grapefruit. Nitrogen calculated from the amino acids accounted for approximately 70% of the Kjeldahl nitrogen in each of the juices.
Some Relations Between the Chemical and Physical Characteristics of Bovine Muscles
Authors: LOCKETT C. , SWIFT C. E. , SULZBACHER W. L.
Published: August 2006

Variations in the distribution of water in bovine muscles were investigated with histological and chemical analyses. A histological method has been developed to measure the extracellular space. This property, along with water and protein content and pH values, was determined in four muscles from each of four animals. The results indicate that extracellular space varied among the muscles of the animals according to a definite pattern. Among the relations found, extracellular space was positively correlated with the water‐protein ratio, whereas intracellular water content was negatively correlated. The evidence indicates that, in the muscles that characteristically contain a relatively high proportion of water to protein, the additional water is located in extracellular spaces.
Studies on the Fate of Staphylococci During the Processing of Hams
Authors: SILLIKER J. H. , JANSEN C. E. , VOEGELL M. M. , CHMURA N. W.
Published: August 2006

Staphylococci are destroyed during the heat processing of both smoked and fully cooked hams. Although these organisms are capable of growth in the presence of sodium chloride, sodium nitrate, and sodium nitrite in the concentrations used in cored meats, they are readily destroyed in the presence, as well as the absence, of these agents at a temperature of 137° F. Twenty‐two of 53 strains of Staphylococcus aureus were killed in excess of 99% after 10 min exposure at this temperature. Thirty‐one strains exhibited more resistance, but were destroyed in excess of 99.9% after 60 min at 137°F. The significance of these results in terms of previous studies is discussed.
Iron and the Bacterial Spoilage of Shell Eggs
Authors: GARIBALDI J. A. , BAYNE H. G.
Published: August 2006

The finding that iron has a profound effect in increasing both the rate and extent of Pseudomonas spoilage of experimentally infected shell eggs was extended to other egg spoilage bacteria. All bacteria tested were so affected. These gram‐negative bacteria included five strains of Proteus, three of Paracolobactrum, two of Alcaligenes, two of Aerobacter, two of Achromobacter, and two of Salmonella.
Quantitative Aspects of the Interaction of Carrageenan with Cationic Substances
Authors: GRAHAM HORACE D. , THOMAS LINNIE B.
Published: August 2006

Using the interaction of carrageenan (Seakem type 5) with cetylpyridinium chloride as the type example, investigation was made of optimum conditions for the precipitation of carrageenan and its fractions by quaternary ammonium detergents. Found to be very critical factors for quantitative precipitation were the temperature and pH of the reaction medium. Comparatively, the amount of detergent cation bound by a particular sulfated hydrocolloid is indicative of its degree of sulfation.
Biochemical Changes in Fish Muscle During Rigor Mortis
Authors: NAZIR D. J. , MAGAR N. G.
Published: August 2006

Mullets (Mugil dussumieri), Bombay ducks (Harpodon nehereus), and groupers (Epinephalus malabaricus) were stored in crushed ice at about 2°C, and changes in pH, glycogen, lactic acid, inorganic phosphorus, creatine phosphate, ATP, acid‐soluble and Ba‐acetate non‐precipitable ribose, and TMA were studied. Though glycogen decreased and lactic acid increased throughout, no direct relation was observed, and measurable quantities of glycogen were present at the end of the experiment. Inorganic phosphorus increased slowly, and creatine phosphate and ATP decreased, the former at a more rapid rate. The Ba‐acetate non‐precipitable ribose and the ratio of non‐precipitable ribose to acid‐soluble ribose increased continuously. TMA values rose slowly, but were quite low even at the end of the experiment.
Polarographic Studies on Storage of Meats.
Authors: OBARA TETSUJIRO , OGASAWARA YASOKICHI
Published: August 2006

Investigation was made of the influence of pepsin, irradiated pepsin, trypsin, and papain on the polarographic wave of native and denatured beef protein solutions. Beef protein solutions incubated with pepsin or irradiated pepsin show a characteristic change in the second waves of their polarograms. This change is quite similar to that observed with a water extract from stored irradiated beef. Pepsin subjected to low‐level irradiation causes a more pronounced polarographic change in beef protein solutions than does unirradiated pepsin, and has a greater proteolytic action. Beef protein solutions incubated with trypsin or papain show less significant polarographic changes than those incubated with pepsin.
Direct Chromatographic Analysis of Milka
Authors: BASSETTE R. , OZERIS S. , WHITNAH C. H.
Published: August 2006

Some organic chemical compounds were detected in milk by a simple, direct chromatographic analysis of head‐space vapors. After modifying the head‐space gas‐sampling technique by saturating the aqueous solution with sodium sulfate and increasing the amplification of the chromatographic hydrogen flame detector electrometer, some organic compounds were detected at less than 0.1 ppm concentration in milk. Samples of fresh and stored raw milk, with and without off‐flavors, were analyzed successfully. Some volatile chemical compounds developed during storage at 2°C. Off‐flavors were characterized by the development of certain chromatographic peaks. Chromatograms were recorded for analyses of rancid, oxidized, sunlight‐oxidized, and high‐acid milks. A number of chromatographic peaks were characterized as carbonyl from their reaction with hydroxylamine. Acetaldehyde, propionaldehyde, acetone, and 2‐butanone were identified. An indication of the concentration of some of these peaks was obtained by analyzing solutions of 0.1 ppm acetaldebyde, propionaldehyde, and 2‐hexanone added to water and to milk.
Toxin Production in Naturally Separated Liquid and Solid Components in Preparations of Heated Surface‐Ripened Cheese Inoculated with Clostridium botulinum
Authors: GRECZ NICHOLAS , DACK GAIL M.
Published: August 2006

Occasional solid‐liquid separation of soft surface‐ripened cheese packed into test tubes was examined for differences between the components with regard to growth and toxin production of Clostridium botulinum. Botulinum toxin was found in three tubes showing liquid‐solid separation; in each case the toxin was present in the solid but absent from the liquid cheese portion. Two mechanisms were found to be responsible for the peculiar distribution of toxin in liquid‐solid separated cheese: 1) the liquid portion possessed antimicrobial activity preventing the growth of C. botulinum whereas the solid component was antimicrobially inactive; 2) the particles in the solid cheese were able to adsorb botulinum toxin, thus preventing diffusion of preformed toxin into the liquid layer. Separation into a solid and liquid layer could be achieved deliberately by increase of the moisture content of the cheese preparation, or by mixing of thoroughly ripened cheese with relatively fresh cheese. However, in these tubes the toxin—when present—was distributed in essentially equal quantities in the adjacent solid and liquid components.
Alteration of Post‐Mortem Changes in Porcine Muscle by Preslaughter Heat Treatment and Diet Modificationa,b
Authors: SAYRE R. N. , BRISKEY E. J. , HOEKSTRA W.G.
Published: August 2006

Subjecting animals to elevated environmental temperatures immediately before slaughter resulted in increased muscle temperature and a rapid rate of post‐mortem glycolysis as indicated by a rapid pH decline and decreased color intensity. A high‐fat high‐protein low carbohydrate ration improved the water‐binding, color, and texture characteristics of the muscle. The detrimental influence of sugar feeding was less marked than in previous experiments, but muscle from animals receiving the high sucrose ration had the lowest pH and (except for the heat‐treated lot) the highest percent reflectance of all lots at 24 hr post‐mortem. Phosphofructokinase activity was not affected by ante‐mortem treatments and did not appear to be related to glycolytic rate or physical properties of the muscle at 24 hr post‐mortem. The time course of rigor mortis was markedly accelerated by heat treatment.
An Examination of the Free Amino Acids of the Common Onion (Allium cepa)a
Authors: KUON JORGE , BERNHARD RICHARD A.
Published: August 2006

Free amino acids in four onion cultivars were studied by two‐dimensional ascending paper chromatography with the following solvents: 1) phenol‐water, 8:2 (v/v), 2) n‐butanol‐acetic acid‐water, 4:1:5 (v/v) (upper layer); and 1) sec butanol–tert butanol‐methylethyl ketone–water, 4:4:8:5 (v/v), 2) n‐butanol–acetic acid‐water, 4:1:5 (v/v) (upper layer).

The amino compounds identified in the extracts were: glutathione, aspartic acid, cysteine, cystine, glutamic acid, serine, canavanine, asparagine, glycine, arginine, lysine, threonine, tyrosine, methionine sulfoxide, alanine, dihydro‐alliine, S‐methyl cysteine, tryptophan, methionine, valine, phenylalanine, and mixed leuycines. Suspected as present was α‐L‐glutamyl‐S‐[β‐carboxy‐n‐propyI]‐L‐cysteinyl glycine.

Densitometry and colorimetry were used to determine the relative approximate amounts of alanine, aspartic acid, arginine, glutamic acid, glycine, leucines, lysine, methionine sulfoxide, phenylalanine, serine, S‐methyl cysteine, threonine, tyrosine, and valine. The more abundant amino acids were: arginine, glutamic acid, phenylalanine, leucines, tyrosine, lysine, and methionine sulfoxide.
Autoxidation of Fish Oils. II. Changes in the Carbonyl Distribution of Autoxidizing Salmon Oilsa,b
Authors: WYATT C. JANE , DAY E. A.
Published: August 2006

The carbonyl compounds of autoxidizing salmon oil were qualitatively and quantitatively analyzed at predetermined levels of oxidation. The 2‐thio‐barbituric acid (TBA) number, peroxide values, and total carbonyls were determined in addition to the individual volatile and Girard‐T‐isolable carbonyls. The C1‐C12 alkanals, C4C12 alk‐2‐enals, and the C6‐C10 alk‐2,4‐dienals composed the major part of the monocarbonyl fractions. The shorter‐chain carbonyls were predominant, with methanal and propanal in the highest concentration. It appears that the Girard T reagent, as employed in the investigation, degrades the precursors of the volatile carbonyl fraction.

The hydroperoxides were readily destroyed in unpolymerized oil by the Girard T reaction conditions, but as polymerization proceeded the yield of hydroperoxides increased and that of the Girard‐isolable monocarbonyls and malonaldehyde decreased. Polymerization of the salmon oil stabilized a large portion of the measurable hydroperoxides toward the degradative effects of the Girard and TBA reactions.
A Technique for the Study of Lipid‐Soluble Food Flavor Volatilesa,b
Authors: LIBBEY L. M. , BILLS D. D. , DAY E. A.
Published: August 2006

A low‐temperature high‐vacuum distillation technique utilizing a molecular still is described. The flavor volatiles are distilled into liquid N2 traps, transferred to a stainless‐steel helical trap of special design, and then blown into a gas chromatograph. Identification of the flavor volatiles is based on relative specific retention volume and collection of the fractions for analysis by techniques such as mass spectrometry. Results are given for application of the described techniques to study of the lipid‐soluble flavor volatiles of Cheddar cheese.
Gas Chromatography of Chicken and Turkey Volatiles: The Effect of Temperature, Oxygen, and Type of Tissue on Composition of the Volatile Fraction
Authors: PIPPEN E. L. , NONAKA M.
Published: August 2006

Concentrated poultry volatiles were prepared by distilling water from chicken and turkey, extracting volatile components from the distillate with isopentane, and concentrating the dried isopentane extract. These volatiles were investigated by gas chromatography on an apparatus equipped with thermal conductivity detectors. Essentially all volatiles were heat‐produced. Cooking in air, as contrasted to cooking in nitrogen, resulted in a much larger and more complex volatile fraction. Rancid chicken yielded a greater amount of volatiles than did fresh chicken, but qualitatively they were similar. The overall yield of volatile material was greater and of a more complex nature from skin and skin fat than from lean leg and breast muscle. Chromatograms of chicken and turkey volatiles indicated differences in their composition. It was not determined, however, whether the difference in composition was responsible for the different and distinctive flavor of chicken and turkey broths determined by sensory methods. n‐Hexanal and n‐2,4‐decadienal were identified as two of the larger volatile fractions of fresh chicken and turkey and rancid chicken. Information on the nature of chicken and turkey volatiles can also be obtained by directly sampling vapors over the product and subjecting them to dual hydrogen flame chromatography.
Classification of Textural Characteristicsa
Authors: SZCZESNIAK ALINA SURMACKA
Published: August 2006

Definition of texture is reviewed, and a system for classification of textural characteristics of foods is described. The system is based on fundamental rheological principles, and at the same time is suitable for routine use. Textural characteristics are defined and classified into mechanical and geometrical qualities as well as those related to the moisture and fat content of a product. The mechanical characteristics are subdivided into the primary parameters of hardness, cohesiveness, viscosity, elasticity, and adhesiveness, and into the secondary parameters of brittleness, chewiness, and gumminess. It is pointed out that popular terms used to describe texture often denote degrees of intensity of these characteristics. The proposed classification lends itself to use with both objective and subjective methods of texture characterization.
Determination of Chlorophylls, Chlorophyllides, Pheophytins, and Pheophorbides in Plant Materiala
Authors: WHITE R. C. , JONES I. D. , GIBBS ELEANOR
Published: August 2006

Equations have been developed for calculation of the total quantity of pigments consisting of chlorophyll a and its derivatives (chlorophyllide a, pheophytin a, and pheophorbide a) and of chlorophyll b and its derivatives (chlorophyllide b, pheophytin b, and pheophorbide b) in a mixture of these pigments in diethyl ether. Calculations are based on conversion of the chlorophylls and chlorophyllides into the pheophytins and pheophorbides, respectively, by the addition of hydrochloric acid and reading absorbances at two wavelengths. After removal of chlorophyllides a and b and pheophorbides a and b from the diethyl ether solution of the pigment mixture by 0.01N KOH, the quantity of each of the eight components listed above is estimated by indicated experimental and mathematical procedures.
Reaction of Sugar Alcohols with the Anthrone Reagent
Authors: GRAHAM HORACE D.
Published: August 2006

Under appropriate conditions of acid concentration, heating time and temperature of heating, the sugar alcohols react with the anthrone reagent in a quantitative manner. Suitable conditions for reproducible quantitative results are: 0.15% anthrone in concentrated sulfuric acid and a heating time of 60 min at 99°C (in a boiling‐water bath). Color measurement should be made 30 minutes after cooling the reaction tubes in an ice water bath, since the intensity of the colors increased with time. Of the various sugar alcohols tested, the order of reactivity is: Glycerol > sorbitol > mannitol > dulcitol > erythri‐tol > arabitol > ribitol > xylitol. Absorption maxima occurred at 720 mμ, for mannitol, sorbitol, and dulcitol, and at 740 mμ for erythritol. Glycerol and the other sugar alcohols exhibited no sharp absorption maxima.
Age‐Associated Changes in Muscle Composition. The Isolation and Properties of a Collagenous Residue from Bovine Musclea
Authors: GOLL DARREL E. , BRAY R. W. , HOEKSTRA W. G.
Published: August 2006

Age‐associated changes in the chemical composition of bovine biceps femoris muscle were studied. Veal muscle had significantly lower Kjeldahl nitrogen and higher moisture contents than muscle from the three older age groups studied. Muscle from veal and from the oldest group (cows, 10 years) possessed less fat than muscle from the two intermediate groups (steers, 1–2 years, and cows, 5 years). A modified procedure for determination of hydroxyproline and its use directly on mean hydrolysates are described. Use of this technique failed to reveal any significant differences in the hydroxyproline content, and presumably the connective‐tissue content, of muscle from the four groups. Warner‐Bratzler shear‐force values of cores from biceps femoris steaks from the three oldest groups indicated that tenderness decreased with age. A method is given for isolation of large quantities of connective tissue from biceps femoris. Chemical analyses of these connective‐tissue residues are presented, and the possibility is discussed that the veal connective tissue contains large amounts of reticulin.
Nitrogen Balance of Dogs Fed Lime‐Treated Corn Supplemented with Proteins and Amino Acidsa,b
Authors: BRESSANI RICARDO , de VILLARREAL EMELINA M.
Published: August 2006

The effect on the nitrogen balance of young dogs of supplementing lime‐treated corn with small amounts of black bean flour, skim milk, fish flour, and torula yeast was investigated. Although the diets were kept isonitrogenous, all supplements increased nitrogen retention significantly, as did supplementing with lysine and tryptophan. The gain was most marked for skim milk, fish flour, and torula yeast plus lysine, and of sufficient magnitude to be of practical significance for human feeding. The better the protein quality of the supplement, the greater the decrease in nitrogen retention after its removal.
Determination of Malonaldehyde by Ultraviolet Spectrophotometrya
Authors: KWON TAI‐WAN , WATTS BETTY M.
Published: August 2006

Malonaldehyde occurs mainly as the enol form (CHOH = CHCHO) in aqueous solution. The UV absorption spectrum of the compound is pH‐de‐pendent. Below pH 3.0, the compound is s‐cis, planar, having an intramolecular H bond, with absorption maximum at 245 mμ and molar absorptivity (ε) = 1.34 × 104. Above pH 7.0, the compound is completely dissociated and the maximum absorption of the enolate anion occurs at 267 mμ with e = 3.18 × 104. The absorbance difference between acidified and basified malonaldehyde solutions at 267 mμ can be used as a measure of malonaldehyde even in the presence of other compounds that absorb in this spectral region, provided their absorption is not pH‐dependent. This difference is directly proportional to malonaldehyde concentrations from 5 × 10‐6M to 3 × 10‐5M. The method has been successfully applied to the assay of malonaldehyde in distillates from rancid foods. Its sensitivity is only about 40% of the 2‐thiobarhituric acid (TBA) test, but is sufficient to detect threshold levels of rancidity. The test is simpler, much more rapid, and more specific than the TBA test.
Histological Analysis of Wound Healing in Potatoes Treated to Inhibit Sprouting 1. CIPC (Isopropyl‐N‐3‐Chlorophenyl Carbamate) Treatments
Authors: REEVE R. M. , FORRESTER L. JANET , HENDEL C.E.
Published: August 2006

Both wound periderm and sprouting were completely inhibited in freshly harvested cut potatoes treated by evaporation of CIPC (isopropyl‐N‐3‐chlorophenyl carbamate) at 10 ppm and 100 ppm (based on tuber weight) and then incubated at 70–75°F and 88% relative humidity. At 1 ppm CIPC, sprouting at room temperature was only slightly retarded. Wound periderm was completely inhibited in the central tissues and markedly retarded in the cortex of the tubers.

Application of CIPC did not prevent suberization at the wound surface, but the walls of intact cells immediately subjacent were less suberized than those of the cut cells. Concomitant with inhibition of wound periderm, there was a marked enlargement of those cells that would normally have given rise to the wound periderm.

Variability of wound healing rates within different tissue zones of single tubers, and other variation between tubers, are considered significant to problems of sprout control and storage.
Relative Taste Intensities of Selected Sugars and Organic Acidsa
Authors: PANGBORN ROSE MARIE
Published: August 2006

A highly trained taste panel was used to establish the concentrations of fructose, glucose, and lactose equivalent in sweetness to sucrose at threshold and suprathreshold concentrations. The same panel established the sourness of lactic, tartaric, and acetic acids equivalent to that of citric acid at threshold and suprathreshold concentrations. There was no relation between pH, total acidity, and relative sourness. Results obtained from determinations made in water solutions agreed favorably with values reported in the literature. The threshold measurements are considered to be of limited value since the relative taste intensity of these compounds is not a constant but is materially affected by the absolute concentration chosen for comparison. The presence of a slight bitterness in glucose, and a slight, unidentifiable flavor in lactose, appeared to influence the threshold determinations. When the sweetness of sucrose and fructose were compared in pear nectar, fructose was less sweet than sucrose at all concentrations (1.0–20.0% sucrose). Increasing the total acidity of the pear nectar had little or no effect on the relative sweetness of these two sugars.
Measurement of Discoloration in Fresh Beefa
Authors: SNYDER HARRY E.
Published: August 2006

A method is described whereby precise measurement of discoloration in fresh red meats can be achieved. The method utilizes α values obtained from Gardner automatic color‐difference meter readings and depends upon careful control of storage temperature, control of sample area from which readings are taken, and consistent orientation of sample during subsequent readings.

Results obtained with the method indicate considerable variation in discoloration of samples from the same slice of beef round stored at 6°C; a substantial decrease in discoloration with lowered storage temperature; a decrease in discoloration resulting from increased exposure of the sample to air; and the probable importance of respiration by the meat rather than bacterial contamination in determining discoloration at low temperatures (‐2°C).