bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemistry and characteristics of enzyme‐modified whipping proteins
Authors: Gunther R. C.
Published: July 2007

Protein derivatives exhibiting aerating and whiping properties are produced by the action of a proteolytic enzyme on a suitable protein substrate, viz., wheat gluten, soy protein or casein. Various proteolytic enzymes can be utilized in the manufacture of the modified protein derivatives, but those enzymes displaying maximum proteolytic activity in the acid pH range produce whipping proteins with optimum aerating functionality and maximum stability characteristcs. Reaction parameters for the hydrolysis include: type of enzyme, enzyme concentration, temperature, pH and time of reaction. By careful control of these variables, modified proteins with unique and exceptional whipping properties can be produced. Enzyme‐modified whipping proteins are bland, light cream‐colored, spray‐dried powders, soluble in hot or cold water, and functional over the entire pH range. Depending upon the source, protein and conditions of manufacture, products can be produced with a protein content ranging from as low as 50% to as high as 85%, and a whipping functionality equal to or twice that of egg albumen. Unlike egg albumen, these products do not coagulate to any appreciable degree when heated, and depending upon the specific end use of the product, this property may be either an advantage or disadvantage.
Technical problems and opportunities in using vegetable proteins in dairy products
Authors: Morr C. V.
Published: July 2007

The food processing industry is giving increased emphasis to the production and utilization of alternate protein isolate products as functional and nutritional ingredients in an expanding number of formulated food products. Alternate protein sources such as soy and other vegetable proteins offer additional flexibility in formulating foods due to their economics, availability, functionality and nutritional properties. This paper discusses needs for developing soy and vegetable protein isolates with improved flavor, color and functionality for producing simulated dairy foods. It also considers alternative technologies for incorporating soy and vegetable proteins into the formulation so that they may function properly for forming stable solutions, emulsions, foams and gels that resemble those in their natural dairy food counterparts.
Vegetable protein application in whey soy drink mix and ice cream
Authors: Wilding M. Dean
Published: July 2007

Full fat and defatted soy flours have been used successfully as major ingredients in a low cost replacement for milk solids in beverages for human consumption in several countries of the world. Milk solids replacement products using vegetable protein may have limited potential as long as surplus milk solids exist on a world basis. Some of the milk trends that are occurring in the U.S. are discussed as they pertain to future use of vegetable protein. It appears likely that there will be a decline in milk production with a higher per capita disposable income available for the purchase of processed dairy products utilizing vegetable protein. Ice cream is one of the more sensitive test systems in which to evaluate the flavor and functional properties of vegetable protein for use in dairy products. Sensory panel data have shown that properly processed soybean isolate protein can be used as a 50% replacement for milk solids protein with no discernible differences from a control product. These sensory tests in ice cream show significant differences among commercial soy isolates.
Food uses for cottonseed protein
Authors: Spadaro James J. , Gardner Homer K.
Published: July 2007

Cottonseed, available in many countries located in both temperate and tropical climates, is rarely used as a source of edible protein even though its use as food was suggested as carly as 1876. Development of edible protein products from cottonseed has been impeded by the presence of gossypol‐containing pigment glands in the kernels, and the economic value of the oil. Cottonseed flour produced by mechanical pressing has been marketed in limited quantities as two edible protein products. One, known as “Proflo,” is used primarily to impart functional characteristics to baked and confectionery products. The other is used as an ingredient in “Incaparina” to combat malnutrition in Latin America. Because of the manner in which these cottonseed protein products are processed, their full nutritional and functional potentials and versatiliity have not been realized. Recent advances in breeding glandless cottonseed, processing glanded cottonseed (e.g., the liquid cyclone process), and related technology have increased the potential of cottonseed protein for food uses. Flours, concentrates, and isolates differ qualitatively and quantitatively in protein and amino acid composition. Consequently, they have different functional and nutritional characteristics and end uses. Flours and concentrates as well as their texturized counterparts are acceptable as functional and nutritional additives to meat products, baked goods, and cereals. Three isolates including storage protein, nonstorage protein, and a mixture of both have been prepared from flours and concentrates. The storage protein isolate imparts functional characteristics, such as texture, acid solubility and foam stability. The non‐storage protein isolate has good nutritional characteristics primarily because of its high lysine content.
Rapeseed protein products
Authors: Ohlson R. , Anjou K.
Published: July 2007

During recent years somewhat different methods of producing rapeseed protein concentrates (RPC) and isolates (RPI) have been developed. Texturizing of RPC has also been studied. Functional properties of RPC such as solubility, water‐and fat‐binding, emulsifying and foaming have been studied together with their organoleptic properties. Very bland RPC can be produced. How variables obtained in the instrumental analysis are related to those obtained in the sensory analysis has also been studied. Rapeseed flours are comparable to soy flours in water absorption and give higher fat absorption. Oil emulsification and whippability values depend on processing. Rapeseed protein concentrates, and isolates show excellent water‐ and fat‐holding capacity. The isolate is high in oil emulsification and whipping characteristics. Rapeseed protein products can therefore be used as extenders or binders in meat patties or sausages. Their use in bread and other food items also has been studied. Due to high contents of lysine, methionine and cysteine, rapeseed proteins have a higher nutritive value than any other known vegetable protein. Their nutritive value is as high as that of good animal proteins. This has been shown in growth studies on rats and in a nitrogen balance study on studient volunteers. The safety of RPC has been tested through many years. With the exception of a negative effect on the zinc balance in rats, which can be compensated, no negative finding has been recorded.
Sesame protein: A review and prospectus
Authors: Johnson L. A. , Suleiman T. M. , Lusas E. W.
Published: July 2007

Sesame is one of the earliest condiments and crops grown for edible oil. Sesame is consumed directly as sweetmeat, a “peanut butter‐like” product, a candy ingredient, bread condiments, and snack foods. The world production of sesame is about 2,000,000 metric tons. China and India are the largest producers but internally consume their production. Sudan is the largest exporter of seed. Sesame contains 50% oil, which is highly resistant to oxidation, and 25% protein, which has a unique balance of amino acids. Dehulling of sesame for human consumption is important since the hull contains 2–3% oxalic acid, which chelates calcium and has a bitter flavor. Dehulled, defatted meal contains 60% protein, is bland, and contains limited qualities of flatulence‐causing sugars and high quantities of phytic acid. Aqueous processing yields isolated protein containing 72% protein and recovers 56% of the seed protein. Sesame protein is very stable to heat and contains large quantities of methionine. Sesame meal has a PER of about 1.35. Sesame is low in lysine and requires supplementation or can be blended with soy protein to give PERs nearly equivalent to casein. Sesame protein is composed of nearly 80% α‐globulin and 20% β‐globulin. Limited attempts have been made to characterize these 2 fractions. Sesame protein has low solubility that limits food applications in its native form. Sesame protein performs better than other oilseeds in baking applications. Production of sesame is limited to countries where labor is plentiful and inexpensive until indehiscent varieties and/or improved mechanical harvesting techniques are developed. However, intense breeding and engineering research programs are in progress.
Relations between pulsed NMR, wide‐line NMR, and dilatometry
Authors: Van Putte K. , Vermaas L. , Van Den Enden J. , Den Hollander C.
Published: July 2007

Hitherto, solid fat contents often have been expressed as dilatations. Since the development of pulsed NMR into a quick and accurate method for the determination of the solid fat content, while wide‐line NMR still is being used, accurate equations are needed to enable conversion from dilatations to NMR values and vice versa. The inaccuracies arising when NMR values are converted into dilatations are almost equal for the various NMR methods. The direct pulse method in which one mean solid fat factor f is used is the most attractive method to replace dilatometry. For further reduction of the standard deviation when converting NMR values into dilations and vice versa, it will be necessary to split up the fats into groups with similar compositions.
“As I remember it” research on biosynthesis of fatty acids, triglycerides, squalene, and cholesterol
Authors: Popják George
Published: July 2007

Abstract and Summary

Dr. George Popják, recipient of the 1977 Award in Lipid Chemistry, presented a chronological account of his career in lipid biochemistry during, his address to the American Oil Chemists' Society on May 9, 1977, in New York City during the Society's 68th Annual Meeting. The address covers his early work in fetal lipids, through his pioneering studies of cholesterol and squalene biosynthesis, and his present work on mevalonate metabolism. “On reading the citation for this award,”. Dr. Popják said, “I, had difficulty in deciding the topics for this address. I chose, rightly or wrongly, an autobiographical approach and to relate, as best I can remember, how I started and progressed in the study of the biochemistry of lipids.”
Synthesis of 6‐fatty acid esters ofl‐ascorbic acid
Authors: Cousins Raymond C. , Seib Paul A. , Hoseney R. Carl , Deyoe Charles W. , Liang Yun T. , Lillard Donald W.
Published: July 2007

Abstract and Summary

High yields (85%) of 6‐fatty acid esters ofl‐ascorbic acid were obtained by reactingl‐ascorbic acid (1.2 M) in 98~99% sulfuric acid for 36 hr at 20 C with 36% excess fatty acid. In concentrated sulfuric acid,l‐ascorbic acid was rapidly sulfated to produce mainlyl‐ascorbyl 6‐sulfate, which slowly reacted with fatty acid to producel‐ascorbyl 6‐acylate.
Aminimides IV: Antimicrobial activity of 1,1,1‐Tris (2‐hydroxyethyl) amine‐2‐acylimides
Authors: Kabara Jon J. , Vrable Ruth , Ikeda Isao , Okahara Mitsuo
Published: July 2007

Abstract and summary

The newest member of the aminimide family of surfactants was screened for antimicrobial activity. The present report supports past conclusions that chain lengths of C14 or C16 gave maximum activity to the aminimide derivative. When a number of hexadecane compounds with different polar groups were compared, the aminimide exhibited wide spectrum antimicrobial activity. Although the functional group was important, the length and character of the acyl chain also help to determine antimicrobial activity. A new amide antibiotic, Cerulenin, with a 4‐keto‐2‐enyl chain, was more active than the unsaturated isomer. Thus, both the functional grup as well as the chain length contribute to biocidal activity.
New developments in silver resin chromatography ofcis andtrans fatty methyl esters
Authors: Scholfield C. R. , Mounts T. L.
Published: July 2007

Chromatographic separations of geometric isomers of methyl octadecenoates and octadecadienoates on a silver‐treated macroreticular resin are much improved with newer resins of greater surface area and ground to a smaller particle size.cis,cis‐Dienes can be recovered in practical elution volumes. With methanol as solvent small molecules including even radioactive methanol are retarded on the column relative to methyl esters of saturated acids.
Detoxification of argemone oil
Authors: Bose P. K.
Published: July 2007

Argemone mexicana plant, a good natural source of nonedible oil in India can be used for beneficial use if the toxic alkaloids present in the oil are removed. The author suggests purification by acid treatment of the hexane extract of Argemone seeds, then passing the solvent through bone‐charcoal column. The toxic yellow‐colored alkaloids are adsorbed in the column. The colorless oil is obtained on recovery of the solvent.
Rendered quality water white coconut oil
Authors: Nuevo C. R. , Santos M. P. , Gonzales A. L. , Birosel D. M.
Published: July 2007

Abstract and Summary

Practically water white coconut oil prepared by either a physicomechanical (PM) or an improved rural process (RP) is highly stable. It has low (0.03%) free fatty acid content and needs no further purification to attain edible quality, especially when the fresh coconut flavor so desirable in confectioneries is relished. PM oil has better stability than RP because the former contains more of the major phospholipid. The RP oil reported herein is a marked improvement over a related product which American chemists in the Bureau of Science, Manila, found in local use as early as the start of the 20th century.
Isolation of pure linolenate as its mercuric acetate adduct
Authors: White H. B. , Quackenbush F. W.
Published: July 2007

After addition of mercuric acetate to the unsaturated methyl esters obtained from the methanolysis of linseed oil, linolenate of 99% minimum purity was isolated by means of a liquid‐liquid continuous extraction technique and subsequent decomposition of the mercurial adduet. The methyl linolenate‐mercuric acetate addition compound was extracted with 10% methanol in water from an ether solution of the reaction mixture. Infrared analysis of the regenerated methyl linolenate showed the complete absence oftrans‐linkages. The yield, at least 60% of the linolenic acid present in linseed oil, was considerably higher than that obtained by bromination‐debromination procedures.

The solubility in aqueous solutions of fatty acid derivatives having 3 or more acetoxymer‐euri‐groups/molecule provides an approach to the fractionation of highly unsaturated oils. For example, a fraction having an iodine value of 395 was isolated readily from the methyl esters of pilchard oil by this technique.
Derivatives of jojoba oil as plasticizers for vinyl polymers and Buna‐N rubber
Authors: Fore Sara P. , Pastor H. P. , Hughes J. P. , Bickford W. G.
Published: July 2007

Ten maleinated jojoba oil derivatives were screened as plasticizers in a standard polyvinyl resin formulation and as softeners for Buna‐N rubber. Three of these, the methyl and butyl esters and hydrogenated methyl esters of maleinated jojoba acids, were comparable to the reference standard, DOP, as primary plasticizers for the vinyl resin. Three others were satisfactory only as secondary plasticizers. Six of the derivatives were comparable to the reference softener, dibutyl sebacate, as softeners in a Buna‐N formulation and yielded rubbers meeting the low temperature flexibility requirements (−40°C.) of the automotive industry. Two of the six, those made with the butyl and hydrogenated butyl esters of maleinated jojoba acids, met the still more stringent low‐temperature requirements of the aircraft industry (−55°C.).

In general, hydrogenation of a derivative adversely affected its compatibility in either the vinyl copolymer or the Buna‐N formulations.
Chemical investigation of the seeds of brassica oleracea var. acephala
Authors: Kaul V. K. , Banerjee A. , Nigam S. S.
Published: July 2007

Fatty acid composition of the seed fat ofBrassica oleracea Var.acephala (Cruciferae) has been determined. Erucic acid has been found to be the major component followed by linoleic, oleic, linolenic, arachidic and palmitic acids. Traces of stearic and eico‐senoic acids have also been detected. The unsaponifiable matter contained β‐sitosterol, and defatted seeds showed the presence of sucrose.
Potentialities of oilseed flours and proteins for replacing black gram components in the texture of leavened foods
Authors: Susheelamma N. S. , Rao M. V. L.
Published: July 2007

Defatted peanut and sesame flours in aqueous dispersions exhibit good surface activity ascribable to their protein content and com‐parable to that of black gram. Soy flour possesses twice as much surface activity as the other flours. Contrasted with black gram, foam matrices obtained with these dispersions are unstable to heat and have low viscosities. Addition of viscous polysaccharide stabil‐ized the foam against thermal disruption. Oilseed flours appear to qualify as good alternatives for the surface active component and viscous hydrocolloids such as guar gum or gelatinized starch may be alternatives for the arabinogalactan of black gram. This combination effectively replaces the pulse in imparting the characteristic soft, spongy texture to leavened foods.
The determination of polyoxyethylene nonionic surfactants in water at the parts per million level
Authors: Crabb N. T. , Persinger H. E.
Published: July 2007

A method has been developed to determine the concn of polyoxyethylene nonionic surfactant (PNS) in the parts/million concn range in a water‐bacteria medium. The method has successfully determined the concn of PNS during the course of biodegradation studies using either activated sludge or river water as the bacterial source. The nonionic surfactant was removed from the water solution by continuous ether extraction. Detection and measurement of the PNS was accomplished using cobalt thiocyanate and measuring the absorbance of the blue cobalt‐PNS complex at 620 m.03 in a five‐cm absorption cell. Optimum extraction conditions required a neutral pH and a low ionic strength. The colorimetric step required that each molecule of PNS contain at least six ethylene oxide units for color development, and since the absorbance varies with the length of the polyoxyethylene chain, the method must be standardized using the particular compound under investigation.
Measurement oftrans and other isomeric unsaturated fatty acids in butterand margarine
Authors: Smith L. M. , Dunkley W. L. , Franke A. , Dairiki T.
Published: July 2007

A procedure is described for gas liquid chromatographic determination of cis andtrans isomers of unsaturated fatty acids after fractionation of the saturated, monenoic, dienoic, and polyenoic fatty acid methyl esters by argentation thin layer chromatography. To test its reliability, the procedure was used for quantitative measurement of transisomers of unsaturated fatty acids in a known mixture of simple triglycerides containing saturated fatty acids from 4:0 to 24:0 andcis andtrans isomers of 14:1. 16:1, 18:1, and 18:2. Results of the analyses of five margarine and five butter samples are presented, together with results of infrared spectrophotometric analyses fortrans fatty acid concentrations, ultraviolet spectrophotometric analyses for conjugated fatty acid concentrations, and enzymatic analyses forcis‐cis‐methylene interrupted fatty acid concentrations. The combined argentation thin layer and gas Chromatographic procedure is suitable for determination of the principal fatty acids in complex food lipids such as milk fat.
Removal of phosphorus and iron by commercial degumming of soybean oil
Authors: List G. R. , Evans C. D. , Black L. T. , Mounts T. L.
Published: July 2007

Samples of crude and water‐degummed soybean oils were obtained from five commercial processors. period of at least 2 weeks between samples. The crude and degummed oils were analyzed for iron and phosphorus content. Phosphorus removal within each processing plant was consistent, but between plants removal varied from a low of 79% to a high of 95%. Removal of iron compounds during commercial degumming varied from a low of 14% to a high of 57%. Significance of these results in steam‐refining operations are discussed.
Oil and water analysis of sunflower seed by near‐infrared reflectance spectroscopy
Authors: Robertson J. A. , Barton F. E.
Published: July 2007

The applicability of NIR for oil and moisture analyses of sunflower seed was determined using a NIR spectrocomputer system. The method was compared with the wide‐line NMR method for oil analysis and with the A.O.C.S. oven method for moisture analysis. The NIR was calibrated with 120 samples for oil (96 for calibration, 24 for prediction) and 63 samples for moisture (55 for calibration, 8 for prediction). Twenty‐two sunflower seed samples were analyzed for oil and moisture by NIR and by methods used by industry. The oil contents of the samples by NMR and NIR were not significantly different. The overall mean oil contents and mean of the standard deviations for the samples were: NMR, 44.2%±0.35% and NIR, 44.34%±0.74%. A significant difference was found between the moisture values obtained by the oven‐drying method and NIR. The average standard deviation for moisture by NIR was 0.57% compared with 0.07% for the oven‐drying method. The variability of the oil content in one of the commercial seed samples was 1.52% oil as determined by NMR and 2.52% as determined by NIR. The advantages and disadvantages of both methods are discussed.
Phospholipids plus tocopherols increase soybean oil stability
Authors: Hildebrand D. H. , Terao J. , Kito M.
Published: July 2007

The phospholipids (PL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were purified from commercial soybean lecithin by silicic acid chromatography and preparative silica gel thin layer chromatography (TLC). Purified phosphatidylinositol (PI) was obtained commercially. Phosphatidic acid (PA) was made from PC by phospholipase D action and purified by preparative TLC. Commercial soybean tocopherols (TOC) were further purified in a florisil column. Combinations of PL and TOC were added to commercially refined, unhydrogenated soybean oil to determine the effects and interaction of PL and TOC on soybean‐oil stability. Oil stability was determined by measuring the time in days of oil samples incubated at 110C to reach a peroxide value of 100 meq/kg. Additions of TOC and all PL except PA increased the stability of the oil. PI and PE appear to be more effective than PC in increasing oil stability. The effect of the PL was not simply a matter of pro‐oxidant metal inactivation, but rather appeared to extend the effectiveness of the TOC in free‐radical termination.
Thermal isomerization of jojoba wax
Authors: Galun Arjeh B. , Shaubi Eleonora
Published: July 2007

Jojoba wax was thermally isomerized over a range of temperatures. The equilibrium constant and the rates ofcis‐trans andtrans‐cis conversions were measured. Activation energy (∼ 24 kcal/m) and enthalpy were calculated.
The fatty acid composition of gymnospermae seed and leaf oils
Authors: Vickery J. R. , Whitfield F. B. , Ford G. L. , Kennett B. H.
Published: July 2007

Of 12 Gymnospermae seed and leaf oils, only 2 contained cyclopropene fatty acids. All‐cis 5, 11, 14, 17‐eicosatetraenoic acid occurred in concentrations up to 11.9% in 6 seed oils, and up to 61% in 2 leaf oils. The structure of this acid, as its methyl ester, was established by the combination of physical (UV, IR,1H‐ and13C‐NMR and mass spectra) and chemical techniques. Arachidonic acid also occurred in 2 seed oils.
Gas chromatographic separation of long‐chain fatty nitriles and long‐chain acid amides
Authors: Wang C. N. , Metcalfe L. D.
Published: July 2007

A method is described for the chromatographic separation of long‐chain fatty nitriles and long‐chain acid amides on a cyanopropyl silicone column. We found that better separations were obtained for these compounds using a cyano column than with any column previously reported.
A new continuous solvent extractor for oleaginous substances
Authors: Smith Charles T.
Published: July 2007

The design of a new continuous extractor for oleaginous substances has been described. Various details of the design have been pointed out, which indicate that the extractor may be applied to a wide range of operating conditions. Typical engineering data on solution retention by solids have been included, and their application to the design of the extractor has been indicated.
A study of some of the properties of silver soaps
Authors: Cheremisinoff Paul N.
Published: July 2007

Silver soaps of several commercially available fatty acids, with varying percentages of different components acids, have been prepared.

Properties: oxide, water soluble matter, acetone soluble matter and thermal contraction or softening points. Appearance of these silver cups is reported.

Gelling characteristics of each of the soaps in xylene are reported.
Apoptosis of Dedifferentiated Hepatoma Cells is Independent of NF-κB Activation in Response to LPS
Authors: Reidy M. Ryan , Ellis Janette , Schmitz Erin A. , Kraus David M. , Bulla Gary A.
Published: July 2007

Dedifferentiated hepatoma cells, in contrast to most other cell types including hepatoma cells, undergo apoptosis when treated with lipopolysaccharide (LPS) plus the protein synthesis inhibitor cycloheximide (CHx). We recently reported that the dedifferentiated hepatoma cells also exhibit a strong and prolonged NF-κB induction phenotype upon exposure to LPS, suggesting that NF-κB signaling may play a pro-survival role, as reported in several other cell systems. To test the role of NF-κB in preventing LPS-mediated apoptosis, we examined the dedifferentiated cell line M38. Results show that antioxidants strongly inhibited LPS + CHx-mediated cell death in the M38 cells, yet only modestly inhibited NF-κB induction. In addition, inhibition of NF-κB translocation by infection of the M38 cells with an adenoviral vector expressing an IκBα super-repressor did not result in LPS-mediated cell death. These results suggest that unlike TNFα induction, the cell survival pathway activated in response to LPS is independent of NF-κB translocation in the dedifferentiated cells. Addition of inhibitors of JNK, p38 and ERK pathways also failed to elicit LPS-mediated apoptosis similar to that observed when protein synthesis is prevented. Thus, cell survival pathways other than those involving NF-κB inducible gene expression or other well-known pathways appear to be involved in protecting the dedifferentiated hepatoma variant cells from LPS-mediated apoptosis. Importantly, this pro-apoptotic function of LPS appears to be a function of loss of hepatic gene expression, as the parental hepatoma cells resist LPS-mediated apoptosis in the presence of protein synthesis inhibitors.
Newborn screening in North America
Authors: Therrell Bradford L. , Adams John
Published: July 2007

Newborn screening in North America dates to the early work of Bob Guthrie in the USA. Screening programmes in both the USA and Canada began in the early 1960s, with documented programmes in both countries as early as 1962. Throughout the 1960s and 1970s, many of the screening tests that later became part of routine screening around the world were developed in US and Canadian laboratories, including tests for phenylketonuria, other inborn errors of metabolism, congenital hypothyroidism, congenital adrenal hyperplasia, and haemoglobinopathies. An automated punching machine developed in the USA facilitated screening expansion by significantly reducing sample preparation time and effort. US and Canadian programmes were leaders in applying computerized data management to newborn screening in the 1980s. In the 1990s, DNA and tandem mass spectrometry testing protocols were developed in the USA and applied to newborn screening. US programmes have continually expanded over time, while most Canadian programmes have not. With impetus from private laboratories and professional and consumer groups, many US programmes now screen for more than 50 conditions and there is increased expansion activity in Canada. NBS research in the USA is focused on improving system efficiency and translating other genetic testing to NBS, particularly where new technologies and treatment therapies exist. Although national newborn screening policies do not exist in either Canada or the USA, there are intense efforts to provide uniform access to screening nationwide in both countries. New partnerships between health professionals, consumers and politicians are benefiting the overall screening systems in both countries.
Theoretical and experimental studies of the radiative properties of hot dense matter for optimizing soft X-ray sources
Authors: Orlov N.Yu. , Gus'kov S.Yu. , Pikuz S.A. , Rozanov V.B. , Shelkovenko T.A. , Zmitrenko N.V. , Hammer D.A.
Published: July 2007

Theoretical and experimental studies of radiative properties of hot dense plasmas that are used as soft X-ray sources have been carried out depending on the plasma composition. Important features of the theoretical model, which can be used for complex materials, are discussed. An optimizing procedure that can determine an effective complex material to produce optically thick plasma by laser interaction with a thick solid target is applied. The efficiency of the resulting material is compared with the efficiency of other composite materials that have previously been evaluated theoretically. It is shown that the optimizing procedure does, in practice, find higher radiation efficiency materials than have been found by previous authors. Similar theoretical research is performed for the optically thin plasma produced from exploding wires. Theoretical estimations of radiative efficiency are compared with experimental data that are obtained from measurements of X-pinch radiation energy yield using two exploding wire materials, NiCr and Alloy 188. It is shown that theoretical calculations agree well with the experimental data.
A low energy tunable pulsed X-ray source based on the pseudospark electron beam
Authors: Wong C.S. , Woo H.J. , Yap S.L.
Published: July 2007

A low energy pulsed X-ray source with 17 J electrical input energy has been constructed based on the vacuum spark configuration triggered by the pseudospark electron beam. With such a low input electrical energy, the frequently studied X-ray emitting vacuum spark plasma is not obtained. Instead, this configuration gives rise to a point-like electron beam-target pulsed X-ray source at the tip of the anode. Emission of X-ray is observed during the pre-breakdown phase. The X-ray spectrum is dominated by the characteristic line emission of the anode material. The total X-ray energy emission from the source can be estimated by assuming it to be a monochromatic point source. It is found to have an X-ray production efficiency of 0.1%, giving an average X-ray dosage of 18 mGy per pulse. X-ray radiography of small biological sample is demonstrated to illustrate a potential application of the present X-ray source.
Robust syntaxin-4 immunoreactivity in mammalian horizontal cell processes
Authors: HIRANO ARLENE A. , BRANDSTÄTTER JOHANN HELMUT , VILA ALEJANDRO , BRECHA NICHOLAS C.
Published: July 2007

Horizontal cells mediate inhibitory feed-forward and feedback communication in the outer retina; however, mechanisms that underlie transmitter release from mammalian horizontal cells are poorly understood. Toward determining whether the molecular machinery for exocytosis is present in horizontal cells, we investigated the localization of syntaxin-4, a SNARE protein involved in targeting vesicles to the plasma membrane, in mouse, rat, and rabbit retinae using immunocytochemistry. We report robust expression of syntaxin-4 in the outer plexiform layer of all three species. Syntaxin-4 occurred in processes and tips of horizontal cells, with regularly spaced, thicker sandwich-like structures along the processes. Double labeling with syntaxin-4 and calbindin antibodies, a horizontal cell marker, demonstrated syntaxin-4 localization to horizontal cell processes; whereas, double labeling with PKC antibodies, a rod bipolar cell (RBC) marker, showed a lack of co-localization, with syntaxin-4 immunolabeling occurring just distal to RBC dendritic tips. Syntaxin-4 immunolabeling occurred within VGLUT-1-immunoreactive photoreceptor terminals and underneath synaptic ribbons, labeled by CtBP2/RIBEYE antibodies, consistent with localization in invaginating horizontal cell tips at photoreceptor triad synapses. Vertical sections of retina immunostained for syntaxin-4 and peanut agglutinin (PNA) established that the prominent patches of syntaxin-4 immunoreactivity were adjacent to the base of cone pedicles. Horizontal sections through the OPL indicate a one-to-one co-localization of syntaxin-4 densities at likely all cone pedicles, with syntaxin-4 immunoreactivity interdigitating with PNA labeling. Pre-embedding immuno-electron microscopy confirmed the subcellular localization of syntaxin-4 labeling to lateral elements at both rod and cone triad synapses. Finally, co-localization with SNAP-25, a possible binding partner of syntaxin-4, indicated co-expression of these SNARE proteins in the same subcellular compartment of the horizontal cell. Taken together, the strong expression of these two SNARE proteins in the processes and endings of horizontal cells at rod and cone terminals suggests that horizontal cell axons and dendrites are likely sites of exocytotic activity.
Tracer coupling between fish rod horizontal cells: Modulation by
light and dopamine but not the retinal circadian clock
Authors: RIBELAYGA CHRISTOPHE , MANGEL STUART C.
Published: July 2007

Horizontal cells are second order neurons that receive direct synaptic
input from photoreceptors. In teleosts horizontal cells can be divided
into two categories, cone-connected and rod-connected. Although the
anatomy and physiology of fish cone horizontal cells have been extensively
investigated, less is known about rod horizontal cells. This study was
undertaken to determine whether light and/or the circadian clock
regulate gap junctional coupling between goldfish rod horizontal cells. We
used fine-tipped, microelectrode intracellular recording to monitor rod
horizontal cells under various visual stimulation conditions, and tracer
(biocytin) iontophoresis to visualize their morphology and evaluate the
extent of coupling. Under dark-adapted conditions, rod horizontal cells
were extensively coupled to cells of like-type (homologous coupling) with
an average of ∼120 cells coupled. Under these conditions, no
differences were observed between day, night, the subjective day, and
subjective night. In addition, under dark-adapted conditions, application
of the dopamine D2-like agonist quinpirole (1 μM), the
D2-like antagonist spiperone (10 μM), or the
D1-like antagonist SCH23390 (10 μM) had no effect on rod
horizontal cell tracer coupling. In contrast, the extent of tracer
coupling was reduced by ∼90% following repetitive light (photopic
range) stimulation of the retina or application of the
D1-agonist SKF38393 (10 μM) during the subjective day and
night. We conclude that similarly to cone horizontal cells, rod horizontal
cells are extensively coupled to one another in darkness and that the
extent of coupling is dramatically reduced by bright light stimulation or
dopamine D1-receptor activation. However, in contrast to cone
horizontal cells whose light responses are under the control of the
retinal clock, the light responses of rod horizontal cells under
dark-adapted conditions were similar during the day, night, subjective
day, and subjective night thus demonstrating that they are not under the
influence of the circadian clock.
Graphs with Large Girth Not Embeddable in the Sphere
Authors: CHARBIT PIERRE , THOMASSÉ STÉPHAN
Published: July 2007

In 1972, Rosenfeld asked if every triangle-free graph could be embedded in the unit sphere Sd in such a way that two vertices joined by an edge have distance more than $\sqrt 3$(ie, distance more than 2π/3 on the sphere). In 1978, Larman [LAR] disproved this conjecture, constructing a triangle-free graph for which the minimum length of an edge could not exceed $\sqrt{8/3}$. In addition, he conjectured that the right answer would be $\sqrt{2}$, which is not better than the class of all graphs. Larman'sconjecture was independently proved by Rosenfeld [MR] and Rödl [VR[. In this last paper it was shown that no bound better than $\sqrt 2$ can be found for graphs with arbitrarily large odd girth. We prove in this paper that this is stilltrue for arbitrarily large girth. We discuss then the case of triangle-free graphs with linear minimum degree.
Genetically modified rules: the awkward rule–exception–right distinction inEC–Biotech
Authors: BROUDE TOMER
Published: July 2007

The arcane distinction between ‘rules’, ‘exceptions’, and ‘autonomous rights’ has troubled WTO dispute settlement since its earliest days, primarily with respect to procedural burden-of-proof questions. Yet in its report, theEC–Biotechpanel relied on a techno-textual understanding of this distinction to interpret the substantive applicability of Articles 2.2, 5.1, and 5.7 SPS – the WTO’s fundamental rules on the degree of scientific certainty of risk required to allow a state to restrict imports of goods due to human, animal, or plant health or life concerns. This article critiques the panel’s approach on the backdrop of WTO jurisprudence and deontic logic, arguing that the norm-category of ‘autonomous rights’ does not actually exist; that the Article 2.2–5.1/5.7 SPS relationship should be more straightforwardly construed than the panel’s analysis would suggest; and that the disorderly and incoherent outcome of the panel’s analysis serves as a cautionary tale against excessive textualism in WTO dispute settlement.
Post-normal science in the multilateral trading system: social science expertise and theEC–BiotechPanel
Authors: FOOTER MARY E.
Published: July 2007

The recentEC–Biotechcase highlights the emerging regulatory divide between WTO Members and reveals a deepening crisis over issues of science and governance in the world trading system. This article focuses on the potential role that social science expertise might play as an analytical tool in understanding trade disputes involving scientific expertise relating to matters of risk assessment and polycentric decision-making. Particular consideration is given to the paradigm of ‘post-normal’ science, which pertains in situations where competent national authorities have to frame and implement policies before all the (scientific) facts are known. As theamicus curiaebrief by a group of five social scientists before theEC–BiotechPanel demonstrates, where there is a high degree of scientific uncertainty, as in the case of GM products, post-normal science can offer a valuable means of framing the dispute in a broader societal context than the sound science approach, which is used to assess health, safety, and environmental risks under the SPS Agreement.
An explanation for high‐frequency broadband electrostatic noise in the Earth's magnetosphere
Authors: Moolla S. , Bharuthram R. , Singh S. V. , Lakhina G. S. , Reddy R. V.
Published: July 2007

A parametric study of high‐frequency nonlinear electrostatic oscillations in a magnetized plasma consisting of hot electrons, cool electrons, and cool ions has been conducted. The fluid equations have been used for each species, and the coupled system of differential equations in the rest frame of the propagating wave have been numerically solved to yield the electric field for parameters characteristic of the auroral region. The effect of the initial driving amplitude, cold and hot electron densities, propagation angle, hot electron drift, and cool electron and cool ion temperatures on the electric field structures have been investigated and, in particular, the frequency and the type of electric field structure (sinusoidal, sawtooth, or spiky). The initial driving amplitude as well as the cold and hot electron densities are shown to affect the nature (sinusoidal, sawtooth, or spiky) of the waveforms, with a transition from linear sinusoidal waveforms for low initial driving amplitude, to spiky, nonlinear waveforms for larger values of the initial driving amplitude. In addition, the drifts of the species are shown to play a crucial role in the periods of the waveforms, while the temperatures of the electron species are also shown to vary the periods of the waveforms but not as much as in the case of the drifts of the species. The results show a strong resemblance to satellite observations of the different types of broadband electrostatic noise reported, which are nonlinear, spiky structures of varying amplitude and period.
Influence of lithosphere viscosity structure on estimates of fault slip rate in the Mojave region of the San Andreas fault system
Authors: Johnson Kaj M. , Hilley George E. , Bürgmann Roland
Published: July 2007

It is well known that slip rate estimates from geodetic data are nonunique because they depend on model assumptions and parameters that are often not known a priori. Estimates of fault slip rate on the Mojave segment of the San Andreas fault system derived from elastic block models and GPS data are significantly lower than estimates from geologic data. To determine the extent to which the slip rate discrepancy might be due to the oversimplified models of the rheology of the lithosphere, we develop a two‐dimensional linear Maxwell viscoelastic earthquake cycle model and simultaneously estimate fault slip rates and lithosphere viscosity structure in the Mojave region. The model consists of episodic earthquakes in an elastic crust overlying layers with different viscosities that represent the lower crust, uppermost mantle, and upper mantle. We use GPS measurements of postseismic relaxation following the 1992 Landers earthquake, triangulation measurements spanning 1932–1977, GPS measurements of the contemporary velocity field, and paleoseismic data along the San Andreas fault. We infer lower crustal (15–30 km depth) viscosity of ∼1019–1020 Pa s, uppermost mantle (30–60 km) viscosity of ∼1020–22 Pa s, and underlying upper mantle viscosity of ∼1018–1019 Pa s, consistent with inferences from laboratory experiments of relatively high‐viscosity lithospheric mantle and lower‐viscosity lower crust and underlying asthenospheric mantle. We infer a 20–30 mm/yr slip rate on the San Andreas fault, in agreement with the lower end of geologic estimates. Inversions of geodetic data with models that do not incorporate layered viscosity structure may significantly misestimate slip rates.
Climatically controlled chemical and biological development in Arctic lakes
Authors: Michelutti Neal , Wolfe Alexander P. , Briner Jason P. , Miller Gifford H.
Published: July 2007

We investigated the factors controlling lake evolution in Arctic ecosystems using a multiproxy paleolimnological approach on a small lake on Baffin Island, Arctic Canada. Lakewater pH was inferred from fossil diatom assemblages, whereas primary production was assessed from sediment concentrations of diatom valves and spectrally inferred chlorophyll a. Our reconstructed limnological variables registered synchronous changes and showed a close coupling to Holocene climatic fluctuations, as inferred by numerous independent paleoclimate proxies. Without exception, our highest pH and production values occurred during warm intervals, and vice‐versa. A return towards paleolimnological conditions of the warm early Holocene has occurred since the midtwentieth century, corresponding to climate warming following the Little Ice Age. Maximum recent values of our reconstructed parameters are either directly comparable to, or in some cases exceed, values attained during the Holocene Thermal Maximum, 8000–10,000 years ago. Our data suggest that climate has a first‐order influence on primary production and the regulation of in‐lake DIC dynamics (and hence on lakewater pH) through its modulation of lake ice cover. We conclude that direct forcing by climate is more important than catchment processes in controlling the chemical and biological development of ice‐dominated Arctic lake ecosystems, at the scale of the Holocene.
Electromagnetic scattering of Gaussian beam by two‐dimensional targets
Authors: Wang Yunhua , Guo Lixin , Wu Zhensen
Published: July 2007

On the basis of the equivalence principle and reciprocity theorem, the multiple scattering up to Nth order by N parallel two‐dimensional (2‐D) targets arbitrarily located in a Gaussian beam is considered. The first‐order solution can be obtained by calculating the scattered field from isolated targets when illuminated by a Gaussian beam. However, it is almost impossible to find an analytical solution for the higher‐order scattered field if the 2‐D targets are not circular cylinders because of the difficulty in formulating the couple scattered field. In order to overcome this problem, the composite scattering field is studied by employing the technique based on the reciprocity theorem and equivalence principle, and a line integral solution up to Nth order is obtained. In this calculation, only the previous‐order scattered field from scatterers and the equivalent surface electric and/or magnetic current density induced by the incident beam are required. Using the approach proposed in this paper, the bistatic and the monostatic scattering fields of a Gaussian beam by parallel inhomogeneous plasma‐coated conducting circular cylinders are calculated, and the dependences of attenuation of the scattering width on the thickness of the coated layer, electron number density, collision frequency, and radar frequency are discussed in detail.
Analysis of flow competence in an alluvial gravel bed stream, Dupuyer Creek, Montana
Authors: Whitaker Andrew C. , Potts Donald F.
Published: July 2007

Critical shear stress and unit discharge flow competence models were tested against coarse bed load data from Dupuyer Creek, Montana, United States. Maximum particle sizes sampled (Dmax) and D50 to D90 percentiles in the bed load grain size distribution were well correlated with both shear stress and unit discharge. Bed load grain sizes became coarser with increasing flow strength. For the Dmax curve, Shields dimensionless parameter for the surface D50 was estimated at 0.044, and the exponent for relative particle size (Di/D50) was −0.59. In the unit discharge criterion the critical flow to entrain the surface D50 was poorly predicted. Flow competence relationships based on Dmax are prone to the influence of outliers and sample mass variability. The mean of the three largest particles, Dmax (3), is more sensitive to changes in flow strength than the D50 to D90 bed load grain sizes, and may represent a good compromise.