bluuebunny/crossref_metadata_2025 huggingface dataset:
Headspace Gas Chromatographic Determination of Residual 1,3-Butadiene in Rubber-Modified Plastics and Its Migration from Plastic Containers into Selected Foods
Authors: Mcneal Timothy P , Breder Charles V
Published: February 2020

A headspace gas chromatographic procedure has been developed for the determination of 1,3-butadiene in rubber-modified plastics and in some foods. Polymer solutions or foods are equilibrated in sealed vials at 90°C, and headspace samples are injected into a gas chromatograph. 1,3-Butadiene residues are measured using a flame ionization detector and are quantitated by the method of standard additions or an external calibration curve. Refrigerator tubs, vegetable oil bottles, chewing gum, and foods in contact with this type of packaging were analyzed. Limits of quantitation varied with the matrix, ranging from 2 ng/g (ppb) in chewing gum to 20 ng/g in polymers. 1,3-Butadiene was found in one polymer at 53 ng/g with an 8% coefficient of variation. The procedure yields "apparent" trace levels of 1,3-butadiene, and confirmation by a complementary technique is required.
Rapid Determination of Methyl Mercury in Fish and Shellfish: Method Development
Authors: Hight Susan C , Corcoran Mary T
Published: February 2020

The AOAC official first action method for methyl mercury in fish and shellfish was modified to provide more rapid determination. Methyl mercury is isolated from homogenized, acetone-washed tissue by addition of HC1 and extraction by toluene of the methyl mercuric chloride produced. The extract is analyzed by electron capture gas chromatography (GC) on 5% DEGS-PS treated with mercuric chloride solution. The quantitation limit of the method is 0.25 μg Hg/g. Swordfish, shark, tuna, shrimp, clams, oysters, and NBS Research Material-50 (tuna) were analyzed for methyl mercury by the AOAC official first action method. All products also were analyzed by the modified method and the AOAC official method for total Hg. In addition, selected extracts obtained with the modified method were analyzed by GC with Hg-selective, microwave-induced helium plasma detection. There was no significant difference between the results for the various methods. Essentially all the Hg present (determined as total Hg) was in the organic form. Coefficients of variation from analyses by the modified method ranged from 1 to 7% for fish and shellfish containing methyl mercury at levels of 0.50-2.30 μg Hg/g. The overall average recovery was 100.5
Gas Chromatographic Method for Determination of Cypermethrin in Pesticide Formulations: Collaborative Study
Authors: Tyler J F C
Published: February 2020

A gas chromatographic method for determination of total cypermethrin in technical and formulated products has been developed and subjected to a collaborative study involving IS participating laboratories. Each sample was dissolved in methyl isobutyl ketone containing di(2-ethylhexyl) phthalate as internal standard and analyzed by gas chromatography on a glass column with 3% OV-101 on Chromosorb W-HP. Each collaborator was furnished with reference stdard and 4 samples of technical material, 3 emulsifiable concentrates, one wettable powder, and one ultralow volume formulation for analysis. The coefficients of variation of the results obtained ranged from 0.955 to 1.7462%. The method has been adopted as official first action by AOAC.
Gas Chromatographic-Thermal Energy Analysis Method for Determination of Volatile N-Nitrosamines in Baby Bottle Rubber Nipples: Collaborative Study
Authors: Gray J Ian , Stachiw Michael A
Published: February 2020

A collaborative study was conducted on the U.S. Food and Drug Administration (FDA) dichloromethane extraction method for determining volatile N-nitrosamines in baby bottle rubber nipples. Following dichloromethane extraction, A'-nitrosamines were determined by gas chromatography-thermal energy analysis. Six pairs of blind duplicate rubber nipple samples representing 6 lots were analyzed by 11 collaborating laboratories. All samples were portions taken from equilibrated composites of cut-up rubber nipples obtained from manufacturers in the United States. Recoveries of the internal standard (N-nitrosodipropylamine) at approximately 20 ppb ranged from 10 to 120%. Reproducibility relative standard deviations (RSDJ were between 35 and 45% for N-nitrosamine levels from 10 to 20 ppb. However, when data from laboratories with recoveries less than 75% were excluded (this is now specified in the method), RSD„ values were between 11 and 32% for N-nitrosamine levels from 6 to 26 ppb. Values were consistent with or better than those reported for other analytical techniques designed to quantitate trace contaminants at the low ppb level, e.g., afiatoxin in foods. The method has been adopted official first action for the quantitation of volatile N-nitrosamines in baby bottle rubber nipples.
Chemical Analysis of Meat Products
Authors: Ellis Richard L
Published: February 2020

Meat, particularly muscle tissue, is basically a 3-component system of protein, moisture, and fat. Although this seems a simple analytical system in which to monitor product composition for regulatory compliance, the simplicity quickly erodes when meat is formulated into the broad variety of products commercially available today. Alternative protein sources, as well as preservatives, binders, extenders, emulsifiers, spices, and other flavoring ingredients, add to the analytes of concern and highlight the need for analytical methods suitable to support inspection and labeling requirements to ensure product compliance. Some key issues are noted which involve protein quality analysis, rapid compositional analysis, isolated soy protein analysis, and minced fish in meat products.
Comparison of Modified Automatic Dumas Method and the Traditional Kjeldahl Method for
Nitrogen Determination in Infant Food
Authors: Bellomonte Guido , Costantini Anna , Giammarioli Stefania
Published: February 2020

This study compares 2 methods for determining nitrogen and protein in various types of infant food: the Kjeldahl method, developed in 1883, which is time consuming and labor intensive, and a newer, automatic method, based on the Dumas method. In each category of infant food considered, the results obtained from both methods are shown to be comparable; however, the modified Dumas method is quicker, easier, and does not pollute the laboratory environment
Amino Acid Analysis by Capillary Gas Chromatography
Authors: Zumwalt Robert W , Desgres Jean , Kuo Kenneth C , Pautz James E , Gehrke Charles W
Published: February 2020

Two developments have enabled major advancements in the use of capillary gas chromatography (GC), the result being its much more widespread use in investigations on a broad range of chemical and biological problems. The 2 technological developments were the introduction of fused silica capillary columns and the development of immobilized stationary phases for capillary GC columns. Because fused silica columns with immobilized stationary phases of varying polarities are offered by numerous vendors of chromatographic equipment, they have become widely used for many analytical tasks. We conducted a study to compare the effectiveness of commercially available fused silica capillary columns with the classical ion-exchange method in the separation and quantitation of amino acids. We selected the /V-trifluoroacetyl (TFA) n-butyl and the A'-heptafloorobutyryl (HFB) isobutyl ester derivatives for this study because of the extensive research and application of these derivatives during the past 20 years. The amino acid content of hydrolysates of 5 materials was measured: ribonuclease,β-lactoglobulin, lysozyme, soybean meal, and a commercial poultry feed. Single 6N HC1 hydrolysates of each material were prepared to minimize sample preparation differences, and 3 independent analyses of each hydrolysate were made by each of 3 techniques: the N-TFA n-butyl and N-HFB isobutyl ester methods using capillary gas chromatography and the ion-exchange chromatographic method using a Beckman 121 M amino acid analyzer. Our results clearly demonstrate that capillary GC analysis of amino acids using fused silica bonded-phase columns provides data with good precision and in general excellent agreement with ion-exchange analyses.
Capillary Column Gas Chromatographic Determination of Trace Residues of the Herbicide Chlorsulfuron in Agricultural Runoff Water
Authors: Ahmad Uaz
Published: February 2020

A capillary column gas chromatographic method is described for determining parts-per-trillion (ppt) levels of chlorsulfuron in agricultural runoff water. The water sample is acidified with acetic acid and extracted with methylene chloride. The chlorsulfuron in the extract is derivatized to its monomethyl derivative. After Florisil column cleanup, the methylated chlorsulfuron is determined by electron-capture gas chromatography. Recovery of chlorsulfuron from fortified water samples is greater than 80%. Detection limit of the method is 25 ng chlorsulfuron/L water (25 ppt). There are 2 reaction sites on the chlorsulfuron molecule, both of which are susceptible to methylation leading to monomethyl chlorsulfuron and dimethyl chlorsulfuron. A procedure is described to methylate selectively the sulfonamide nitrogen of chlorsulfuron.
Determination of Several Halogenated Fumigants in Cereal Products by Steam Distillation and Capillary Gas Chromatography with Electron Capture Detection
Authors: Page Denis B , Newsome Harvey W , Macdonald Stephen B
Published: February 2020

A steam distillation procedure is described for the determination of ethylene dibromide (EDB), ethylene dichloride (EDC), and carbon tetrachloride (CT) in flour, flour-based mixes, baked cakes, breakfast cereals, and citrus fruits. A representative sample is steam distilled using a modified Garman steam distillation apparatus, the steam and volatile components are condensed, and the condensate is partitioned with hexane (EDB) or pentane (EDC and CT). The solvent extract is then injected on-column and analyzed by using a 15 m x 0.32 mm 1.0 μ DB-1701 fused-silica capillary column at 50°C for EDB or a 30 m x 0.25 mm 1.0 μ DB-5 column at 35°C for EDC and CT. For routine EDB determinations as low as 10 ppb, 2 g flour, Hour-based mix, or breakfast cereal is distilled and partitioned into 10 mL hexane. For enhanced sensitivity, up to 10 g dry sample can be concentrated into 1 mL hexane, for detection as low as 0.1 ppb (10% FSD, 2.0 pg). Recoveries from flour spiked with 100, 5, and 0.5 ppb EDB were 98.9, 95.1, and 117%, respectively. Coefficients of variation for marketplace flour samples found to contain EDB at 122,6.0, and 1.2 ppb were 4.6,6.9, and 3.6%, respectively, and for baby cereal at 0.22 ppb, 4.5%. Recoveries for EDC and CT from flour spiked at 46, 94, and 140 ppb were 61,73, and 72%, and 96,95, and 87%, respectivefy. Coefficients of variation were 10.0, 7.8, and 4.8, and 8.0, 3.2, and 8.4%, respectively
Fluorimetric Determination of Anatoxin M1 in Cheese
Authors: Bijl Jan P , Van Peteghem Carlos H , Dekeyser Diana A
Published: February 2020

A simple and sensitive method is proposed for the determination of aflatoxin M, in cheese. The ground cheese sample is extracted with acetone-water (3 + 1). Acetone is evaporated under vacuum, and the aqueous phase is passed through a C18 disposable cartridge. After the cartridge is washed with acetonitrile-water (1 + 9), the toxin is eluted with acetonitrile. The extract is then cleaned up on a silica cartridge. Final analysis is performed by 2-dimensional thin layer chromatography (TLC) combined with fluorodensitometry or by liquid chromatography on a reverse phase C„ column with fluorescence detection. Recovery is greater than 90%, and the coefficient of variation is 6% or less. The detection limit is in the range of 10 ng/kg. The identity of aflatoxin M2, is confirmed by formation of the Mu or acetyl-M1, derivative and rechromatography.
Identification of Mammalian Feces by Thin Layer Chromatography of Coprostanol: Collaborative Study
Authors: Hoskin George P
Published: February 2020

Mammalian feces contain coprostanol (5β-cholestan-3/J-ol). In this study, 7 collaborators each tested 45 unknown specimens by a thin layer chromatographic method that uses coprostanol as an indicator of feces. The materials tested were 5 replicates each of 3 test portion sizes (0.5,1.0, and 5.0 mg) of cockroach excreta (negative), and cow and rat feces (both positive). Of 315 specimens tested, 261 (82.9%) were correctly identified; there were 5 false positives, 26 false negatives, and from 1 collaborator, 23 inconclusive results.
Development of Milk Powder Reference Materials Certified for Aflatoxin M1 Content (Part I)
Authors: Egmond Hans P Van , Wagstaffe Peter J
Published: February 2020

The development of 3 full-cream milk powder reference materials, certified for their aflatoxin M1 content, is described. The materials were prepared and certified within the Reference Material Programme of the Community Bureau of Reference (BCR). The 3 reference materials, RMs 282, 284, and 285, contain aflatoxin M1 at concentrations of <0.05, 0.31 ± 0.06, and 0.76 ± 0.05 μg/kg, respectively. The preparation, testing for homogeneity, stability of the reference materials, and the certification exercise, which was preceded by 2 intercomparisons of methods, are discussed. Particular emphasis was placed on the independence of the measurements in the certification exercise and the control of errors associated with extraction efficiency and the aflatoxin M1 calibrant. Finally, some guidance is given on avoiding the principal sources of error in the determination of aflatoxin M1. Details concerning the supply of the reference materials will be provided by BCR on request.
Recommendations for Establishment of Reference Standards for Recombinant-DNA-Derived Proteins and Polypeptides
Authors: Atkins Lois M , Miner David J , Sittampalam G Sitta , Wentling Charles D
Published: February 2020

An integrated approach is presented for the establishment of purified protein and peptide reference standard materials suitable for both biological and chemical assays. Preliminary considerations, handling and storage conditions, and a variety of chemical methods for defining the reference standards are examined in detail. Of the chemical methods, liquid chromatography (LC), amino acid analysis, Kjeldahl protein assay, electrophoresis, and ion chromatography are key assays in determining the potency, purity, and identity of the reference standard preparation. Finally, the role of liquid chromatography in assessing reference standards for identity and chemical purity is examined and correlated with other methods.
Phase Solubility Analysis of Some Organochlorine Fungicides
Authors: Lesser Joseph H , Massil Solomon E
Published: February 2020

Phase solubility analysis (PSA) was used to establish purities of 3 organochlorine fungicides—chlorothalonil, captan, and folpet. Each ground sample was added to an equal amount of solvent. All vials were mixed at identical constant temperature, equal aliquots of liquid phase were removed and weighed, and concentration of dissolved material was determined by weighing the residue after evaporation to a constant weight. Solvent systems were chosen such that solubility of the fungicides was minimal. Data were analyzed by the leastsquares method with a resulting correlation coefficient of better than 0.94. Spiking experiments were also performed. Analysis of chlorothalonil by differential scanning colorimetry and of captan and folpet by liquid chromatography was in accord with PSA results.
Interlaboratory Study of Blood Selenium Determinations
Authors: Koh Tee-Siaw
Published: February 2020

Fifty-one laboratories from 14 countries participated in a survey on the determination of selenium (Se) in 8 bovine blood samples with Se concentrations ranging from 0.2 μmol/L (0.016 μg/mL) to 14 μmol/L (1.1 μg/mL). The methods used (and the percentage of participants using each method) were fiuorometry (61), hydride-generation atomic absorption spectrophotometry (AAS) (23), graphitefurnace AAS (6), gas chromatography (4), neutron activation analysis (4), and X-ray fiuorometry (2). There was little difference in the mean Se results obtained by fiuorometry or hydride-generation AAS (P > 0.05). Mean intralaboratory coefficients of variation (CVs) from known replicates ranged from 4 to 14% for all samples. Interlaboratory CVs were related to blood Se concentration and increased to 55% at Se levels below 0.4 μmol/L (0.032 μg/mL). Laboratories that used quality control (QC) schemes had lower interlaboratory CVs than those that did not, but the advantage began to diminish at blood Se concentration below 0.4 μmol/L (0.032 μg/mL). The high interlaboratory CVs, coupled with the false assurance from the low intralaboratory CVs and the ineffectiveness of the QC schemes at blood Se concentrations below 0.4 μmol/L (0.032 μg/mL), are of concern in diagnosis of marginal Se deficiency in livestock where the concentrations of interest are in the range 0.15-0.5 μmol/L (0.012-0.039 μg/mL).
New Method for the Determination of 1,1-Dimethylhydrazine Residues in Apples and Peaches
Authors: Wright Dallas
Published: February 2020

A new method for determining 1,1-dimethylhydrazine (UDMH) in peaches and apples is presented. The method consists of extraction with L-ascorbic acid, derivatization with 2-nitrobenzaldehyde to the corresponding hydrazone, and cleanup on an alumina column. The hydrazone derivative is determined by gas chromatography using an electron-capture detector. Recoveries were determined from 10 to 100 ppb. Stability of the UDMH residues on frozen peaches was investigated, and results indicate that the residues degrade even while frozen.
Sulfuric Acid Cleanup and KOH-Ethanol Treatment for Confirmation of Organochlorine Pesticides and Polychlorinated Biphenyls: Application to Wastewater Samples
Authors: HernÁndez Felix HernÁndez , Benet Francisco J.López , Escriche Julio Medina , Ubeda Juan C.Barberá
Published: February 2020

The efficacy of sulfuric acid cleanup and KOH-ethanol hydrolysis confirmation was studied for 22 organochlorine pesticides and 2 polychlorinated biphenyls (PCBs). Mean recoveries for different treatment times are given. The method was applied to analysis of several wastewater samples by gas chromatography with electron capture detection. Organochlorine compounds were extracted by using separatory funnels and 15% diethyl ether in hexane as extractant. All the compounds studied could be analyzed except trifluralin, dichloran, dieldrin, and endrin, which were destroyed after treatment with concentrated H2S04. The pesticides found most commonly in the samples analyzed were fenson, tetradifon, lindane, methoxychlor, and dicofol.
History of the Food and Drug Administration's Total Diet Study-1961 to 1987
Authors: Pennington Jean A T , Gunderson Ellis L
Published: February 2020

The Total Diet Study provides the Food and Drug Administration with baseline information on the levels of pesticide residues, contaminants, and nutrient elements in the food supply and in the diets of specific age-sex groups. The study also identifies trends and changes in the levels of these substances in the food supply and in diets over time and thereby assists in identifying potential public health problems. This paper describes the evolution of the Total Diet Study from 1961 to 1987. Food collections, sites of analysis, diets, food commodity groups, analytes, analytical methodologies, data transfer, publication of results, notable results, resources, and advantages of the study are discussed.
More Powerful Peroxide Kjeldahl Digestion Method
Authors: Hach Clifford C , Bowden Brian K , Kopelove Alan B , Brayton Scott V
Published: February 2020

Enhanced ammonia recovery and a simplified method are described for a rapid Kjeldahl digestion using sulfuric acid and hydrogen peroxide as the sole digestion reagents. This micro procedure uses a Vigreux fractionating head fitted to a 100 mL volumetric flask and a hot plate with a solid-state controller. Continuous-flow peroxide addition is controlled by a capillary funnel, and fumes are evacuated through a side-arm vent leading to a water aspirator. Complete recovery of nitrogen from the refractory compound, nicotinic acid, is obtained with less than 10 min digestion. The described method reduces digestion time by 25-50% over the open-manifold peroxy method. A digestibility index (DI), scaled 0-10, establishes the difficulty of digestion for each sample and assigns values to compounds. A useful tool for determining the minimal amount of reagent and digestion time required, the DI assigns zero for compounds not needing digestion and 10 for nicotinic acid. Digested samples obtained from the described method are suitable for direct colorimetric analysis of many elements in addition to Kjeldahl nitrogen. Distillation of the digested sample is not required
Liquid Chromatographic Determination and Stability of the Fusarium Mycotoxin
Moniliformin in Cereal Grains
Authors: Scott Peter M , Lawrence Guillaume A
Published: February 2020

Moniliformin is a mycotoxin produced by Fusarium subglutinans and other Fusarium species. A rapid, liquid chromatographic method for its determination in corn and wheat is described. Samples are extracted in acetonitrile-water (95 + 5); following defatting with n-hexane, an aliquot of the extract is evaporated and cleaned up on small C18 and neutral alumina columns successively. Reverse-phase liquid chromatography (LC) is conducted on a Ci8 column with 10 or 15% methanol or acetonitrile in aqueous ion-pair reagent as mobile phase, with detection by ultraviolet absorption at 229 and 254 nm. Average recoveries of moniliformin (potassium salt) added to ground corn and wheat at levels of 0.05-1.0 Mg/g were 80% (n = 20) and 85% {it = 12), respectively, and the limit of detection was ca 0.01- 0.18 Mg/g, depending on LC conditions. Analysis of 24 samples of wheat, 4 samples of rye, and 12 samples of corn showed moniliformin in only 2 corn samples (0.06 and 0.2 Mg/g)- Moniliformin was also detected in a sample of artificially damaged (slashed) corn (0.2 Mg/g) and selected kernels of corn that were field-inoculated with F. subglutinans and F. moniliforme (50 Mg/g and 0.5 Mg/g, respectively). In stability studies, moniliformin (potassium salt, 1 Mg/g) >n ground corn and ground wheat heated at 50,100, and 150°C for 0.5-2 h decomposed moderately, e.g., 55% remained in corn after 0.5 h at 100°C
Improved Enzyme-Linked Immunosorbent Assay for Aflatoxin Bj in Agricultural Commodities
Authors: Chu Fun Sun , Fan Titan S L , Zhang Guang-Shi , Xu Yi-Chun , Faust Susan , Mcmahon Philip L
Published: February 2020

An improved enzyme-linked immunosorbent assay (ELISA) for aflatoxin B, in cornmeal and peanut butter was developed. Aflatoxin B, in cornmeal and peanut butter samples was extracted with 70% methanol in water containing 1% dimethylformamide diluted with assay buffer to a final concentration of 7.0% methanol, and directly subjected to an ELISA procedure that took less than 1 h for quantitative analysis and less than 30 min for screening tests. Analytical recoveries for 5-100 ppb B, added to the cornmeal and peanut butter were 91 and 95.4%, respectively. The interwell and interassay coefficient of variation was 10% or less at the 20 ppb level and above. Agreement for B, levels in more than 30 naturally contaminated corn, mixed feed, and peanut butter samples was excellent between the ELISA data and the data obtained from different independent laboratories using TLC or other analytical methods
Two Enzyme Immunoassays to Screen for 2,4-Dichlorophenoxyacetic Acid in Water
Authors: Fleeker James
Published: February 2020

Two solid-phase enzyme immunoassays were developed to measure 2,4-dichlorophenoxyacetic acid (2,4-D), using 2 sets of structurally distinct immunogens and enzyme ligands. The 2,4-D analog, 2-methyl- 4-chlorophenoxyacetic acid (MCPA), gave a similar response with both methods, whereas other phenoxy herbicides cross-reacted differently. In method A, the aromatic moiety of 2,4-D was distal from the carrier protein and labeled enzyme, whereas in method B, the acetic acid portion of the herbicide was distal. The use of both methods to screen for this herbicide in ground water and municipal and river water reduced the number of false-positive responses. Water sources having a low background response could be monitored with either method alone. When a concentration step, with disposable C18 extraction columns, was used, the limit of sensitivity was 5 ng/L,. Method A was the more sensitive of the 2 methods with a limit of detection of 10 j*g/L without the concentration step
Reverse-Phase Liquid Chromatographic Determination of Benzoic and Sorbic Acids in Foods
Authors: Bui Lap V , Cooper Chongchit
Published: February 2020

An isocratic liquid chromatographic (LC) technique is described for the determination of benzoic acid and sorbic acid in foods such as beverages, fruits, seafood, vegetables, sauces, and dairy, bakery, and confectionery products. A C1S column is used with methanol-phosphate buffer (5 + 95) as mobile phase and 4-hydroxyacetanilide or 3,5-dinitrobenzoic acid as internal standard. Sample preparation is simple, rapid, and produces a sample extract that has a minimum effect on the column performance and life. Specificity of the method was checked against common food additives such as i,-ascorbic acid, caffeine, artificial sweeteners (saccharin, cyclamate, aspartame), antioxidants (BHT, BHA) and artificial colors. Also described are 2 procedures for confirmation of the preservatives, using either redox reaction of sorbic acid with potassium permanganate or gas chromatography/ mass spectrometry. Mean recoveries of 90-105% were obtained with a precision of 1-6% and a detection limit of 20 mg/kg for the 2 preservatives
Determination of Phytosterols in Butter Samples by Using Capillary Column
Gas Chromatography
Authors: Smith Randall L , Sullivan Darryl M , Richter Earl F
Published: February 2020

A positive bias in the gas chromatographic (GC) analysis of butter for β-sitosterol was discovered when attempting to confirm values by gas chromatography/mass spectrometry (GC/MS). The source of the problem was traced to an interfering material that was not effectively separated by packed column GC. Because capillary columns are known to provide superior separation, they were substituted for packed columns in the assay, and instrument parameters were modified accordingly. A compound with a similar retention time, identified by GC/MS as lanosterol, was separated from β-sitosterol by the capillary column. The capillary column technique was applied to over 300 butter samples. The results indicate that the method can accurately quantitate β-sitosterol in butter with no known interferences. The limit of detection for this method is 1 mg/100 g. Recoveries at a level of 3 mg/100 g averaged 98% with a coefficient of variation of 3.45%
Comparison of Diethyl Ether and Ethyl Acetate as Extracting Agents for Recovery of Ascaris
spp. and Trichuris spp. Eggs
Authors: Rude Richard A , Peeler James T , Risty Norris G
Published: February 2020

Ethyl acetate and diethyl ether were compared for their ability to recover Ascaris spp. and Trichuris spp. eggs from seeded milorganite, liquid sludge, and cabbage. Concentrations of 10,100, and 1000 eggs/ 10 g test sample were prepared for 20 replicates of each product. The use of diethyl ether yielded fewer eggs/10 g than did ethyl acetate in 5 of 6 sets of data. For Ascaris spp., recovery from cabbage was 10 times higher with ethyl acetate at the higher concentration than with diethyl ether. For Trichuris spp., recovery from liquid sludge was slightly higher with diethyl ether for all egg concentrations. The other results ranged from 0 to 23% difference in recovery for the 2 agents. Depending on the parasites in question and the products to be screened, the substitution of ethyl acetate for diethyl ether may be significant.
Comparison of LECO FP-228 "Nitrogen Determinator" with AOAC Copper Catalyst Kjeldahl Method for Crude Protein
Authors: Sweeney Rose A , Rexroad Paul R
Published: February 2020

The LECO FP-228 "Nitrogen Determinator" was compared with the AOAC copper catalyst Kjeldahl method, 7.033-7.037, for the determination of crude protein in feed materials. The completely microprocessor- controlled instrument determines nitrogen by measuring the nitrogen gas following combustion of the sample; it was easy to operate and broadly applicable. A wide variety of feed materials of various nitrogen levels were analyzed in one mixed sequence. Results were precise, accurate, and rapid. Analysis time for one sample was approximately 3 min. Fourteen samples containing 2.5-15.5% N were selected for study and consisted of meals, grains, forages, and standard organic materials. The overall mean for the 14 samples by the LECO combustion method was 8.61% N compared with an overall mean of 8.58% N for the AOAC Kjeldahl method. Within-sample standard deviations for the LECO combustion method ranged from 0.013 to 0.052% N with a pooled standard deviation (SD) of 0.033% N for the 14 samples. Standard deviations for the AOAC Kjeldahl method ranged from 0.006 to 0.035% N with a pooled SD of 0.022% N. Combined average recovery of nitrogen from tryptophan, lysine- HC1, and EDTA determined by the LECO combustion method was 99.94% compared to 99.88% determined by the AOAC Kjeldahl method.
Colorimetric Determination of a Polymeric Quaternary Ammonium Antimicrobial Preservative in an Ophthalmic Solution
Authors: Good Ralph M , Liao John C , Hook Joan M , Punko Cathy L
Published: February 2020

A simple colorimetric method is presented for the determination of Polyquad®, a polymeric quaternary ammonium antimicrobial preservative, in an ophthalmic solution. Polyquad and magnesium are coprecipitated by ion pairing with Ponceau S, a highly colored sulfonate dye, at an acidic pH. The sample is centrifuged and the supernate analyzed spectrophotometrically. The concentration of Polyquad is determined by the decrease in dye concentration. Formulation excipients such as disodium edetate, dextran, and hydroxypropylraethylcellulose did not interfere with the quantitation. The method is specific, accurate, precise, and stability-indicating for the quantitation of 10 ppm Polyquad.
Enumeration of Clostridium perfringens Spores in Human Feces: Comparison of Four Culture Media
Authors: Harmon Stanley M , Kautter Donald A
Published: February 2020

Enumeration of Clostridium perfringens spores was compared using 4 culture media. Duplicate 1 g portions of 35 stools (25 from C. perfringens food poisoning outbreaks and 10 from normal stools) were heat treated 20 min at 75°C and tested on tryptose-sulfite-cycloserine (TSC) agar, tr ypticase-soy-blood (TSB) agar, lactose-sulfite (LS) medium, and iron milk (IM) medium. Dilutions were plated directly onto TSB and TSC, and a 3-tube most probable number determination was made with each specimen in LS and IM incubated at 45°C. TSB was easiest to use and nonhemolytic food poisoning strains were readily differentiated from the normal hemolytic biotype on this medium. Confirmed counts on TSC and TSB were similar for all specimens, but counts of 8 of 25 outbreak specimens were 2-4 log units lower in LS and IM than on plating media; spores in specimens associated with 2 of 5 outbreaks were intolerant of the elevated temperatures. Results showed that elevated temperature MPN methods in LS and IM are inappropriate for the examination of outbreak stools.
First Report of Sex Chromosomes in Night Lizards (Scincoidea: Xantusiidae)
Authors: Nielsen Stuart V , Pinto Brendan J , Guzmán-Méndez Irán Andira , Gamble Tony
Published: February 2020

Squamate reptiles (lizards, snakes, and amphibians) are an outstanding group for studying sex chromosome evolution—they are old, speciose, geographically widespread, and exhibit myriad sex-determining modes. Yet, the vast majority of squamate species lack heteromorphic sex chromosomes. Cataloging the sex chromosome systems of species lacking easily identifiable, heteromorphic sex chromosomes, therefore, is essential before we are to fully understand the evolution of vertebrate sex chromosomes. Here, we use restriction site-associated DNA sequencing (RADseq) to classify the sex chromosome system of the granite night lizard, Xantusia henshawi. RADseq is an effective alternative to traditional cytogenetic methods for determining a species’ sex chromosome system (i.e., XX/XY or ZZ/ZW), particularly in taxa with non-differentiated sex chromosomes. Although many xantusiid lineages have been karyotyped, none possess heteromorphic sex chromosomes. We identified a ZZ/ZW sex chromosome system in X. henshawi—the first such data for this family. Furthermore, we report that the X. henshawi sex chromosome contains fragments of genes found on Gallus gallus chromosomes 7, 12, and 18 (which are homologous to Anolis carolinensis chromosome 2), the first vertebrate sex chromosomes to utilize this linkage group.
Emotional Legacies, Transitional Justice and Alethic Truth
Authors: Clark Janine Natalya
Published: February 2020

Transitional justice processes seek to address the legacy of past human rights abuses. This article focuses on the emotional dimensions of legacy. It argues that war crimes and human rights abuses leave important emotional legacies that have not received sufficient attention within transitional justice theory or practice, and underscores that any process of ‘dealing with the past’ is necessarily incomplete if powerful emotions connected to that past are overlooked. Drawing on the author’s fieldwork in the Bosnian village of Ahmići, the article aims to demonstrate that the neglect of emotional legacies — which it links to the concept of therapeutic jurisprudence — represents a missed opportunity to explore how the meta emotions that people share constitute potential new bases for building reconciliation in post-conflict societies such as Bosnia-Herzegovina. Reflecting more broadly on the relationship between truth and reconciliation, it emphasizes the utility of alethic truth as a concept that accommodates and draws attention to common emotions — and thus points to unexplored dimensions of the relationship between truth and reconciliation.
Subversive Invisibility during the Cold War: Paule Marshall’s “Brooklyn”
Authors: Parry Shirley
Published: February 2020

This essay explores how Paule Marshall engages issues of leftist politics and homosexuality in “Brooklyn,” her only fiction set during the Cold War. On the surface, this novella, the second in Marshall’s 1961 collection Soul Clap Hands and Sing, is a story of sexual harassment that, she has explained, was based on an experience she had at Brooklyn College. Marshall’s boldness in confronting the sexual and racial politics of the 1950s in the story’s depiction of an African American woman’s sexual harassment by her white professor has been noted by many. But less remarked is the fact that beneath the surface narrative of this story, Marshall has incorporated transgressive subtexts that address leftist politics and homosexuality, two issues that were deeply contested during the McCarthy years. A close examination of “Brooklyn” highlights the previously unrecognized narrative strategies that Marshall employs to both produce and conceal these subversive subtexts, thus creating a story that seems to reject communism at the same time that it incorporates a pro-communist political statement, and that seems to reflect the dominant culture’s assumption of heteronormativity while simultaneously endorsing the necessity of existential choice in the area of sexuality. In addition, Marshall shapes her characters so as to make existential choice more broadly the core theme of the story. This essay also situates the narrative in the context of Marshall’s own political activism as well as in the context of the negative impact that the Cold War political tensions had on African American writers during the 1950s.
Are long-term N-body simulations reliable?
Authors: Hernandez David M , Hadden Sam , Makino Junichiro
Published: February 2020

N-body integrations are used to model a wide range of astrophysical dynamics, but they suffer from errors which make their orbits diverge exponentially in time from the correct orbits. Over long time-scales, their reliability needs to be established. We address this reliability by running a three-body planetary system over about 200 e-folding times. Using nearby initial conditions, we can construct statistics of the long-term phase-space structure and compare to rough estimates of resonant widths of the system. We compared statistics for a wide range of numerical methods, including a Runge–Kutta method, Wisdom–Holman method, symplectic corrector methods, and a method by Laskar and Robutel. ‘Improving’ an integrator did not increase the phase-space accuracy, but simply increasing the number of initial conditions did. In fact, the statistics of a higher order symplectic corrector method were inconsistent with the other methods in one test.
A slow-down time-transformed symplectic integrator for solving the few-body problem
Authors: Wang Long , Nitadori Keigo , Makino Junichiro
Published: February 2020

An accurate and efficient method dealing with the few-body dynamics is important for simulating collisional N-body systems like star clusters and to follow the formation and evolution of compact binaries. We describe such a method which combines the time-transformed explicit symplectic integrator and the slow-down method. The former conserves the Hamiltonian and the angular momentum for a long-term evolution, while the latter significantly reduces the computational cost for a weakly perturbed binary. In this work, the Hamilton equations of this algorithm are analysed in detail. We mathematically and numerically show that it can correctly reproduce the secular evolution like the orbit averaged method and also well conserve the angular momentum. For a weakly perturbed binary, the method is possible to provide a few orders of magnitude faster performance than the classical algorithm. A publicly available code written in the c++ language, sdar, is available on github. It can be used either as a standalone tool or a library to be plugged in other N-body codes. The high precision of the floating point to 62 digits is also supported.
The ASAS-SN catalogue of variable stars VI: an all-sky sample of δ Scuti stars
Authors: Jayasinghe T , Stanek K Z , Kochanek C S , Vallely P J , Shappee B J , Holoien T W-S , Thompson Todd A , Prieto J L , Pejcha O , Fausnaugh M , Otero S , Hurst N , Will D
Published: February 2020

We characterize an all-sky catalogue of ∼8400 δ Scuti variables in ASAS-SN, which includes ∼3300 new discoveries. Using distances from Gaia DR2, we derive period–luminosity relationships for both the fundamental mode and overtone pulsators in the WJK, V, Gaia DR2 G, J, H, Ks, and W1 bands. We find that the overtone pulsators have a dominant overtone mode, with many sources pulsating in the second overtone or higher order modes. The fundamental mode pulsators have metallicity-dependent periods, with log10(P) ∼ −1.1 for $\rm [Fe/H]\lt -0.3$ and log10(P) ∼ −0.9 for $\rm [Fe/H]\gt 0$, which leads to a period-dependent scale height. Stars with $P\gt 0.100\, \rm d$ are predominantly located close to the Galactic disc ($\rm |\mathit{ Z}|\lt 0.5\, kpc$). The median period at a scale height of $Z\sim 0\, \rm kpc$ also increases with the Galactocentric radius R, from log10(P) ∼ −0.94 for sources with $R\gt 9\, \rm kpc$ to log10(P) ∼ −0.85 for sources with $R\lt 7\, \rm kpc$, which is indicative of a radial metallicity gradient. To illustrate potential applications of this all-sky catalogue, we obtained 30 min cadence, image subtraction TESS light curves for a sample of 10 fundamental mode and 10 overtone δ Scuti stars discovered by ASAS-SN. From this sample, we identified two new δ Scuti eclipsing binaries, ASASSN-V J071855.62−434247.3 and ASASSN-V J170344.20−615941.2 with short orbital periods of Porb = 2.6096 and 2.5347 d, respectively.
Interactive Effects of Light Quality and Temperature on Arabidopsis Growth and Immunity
Authors: Liu Xiaoying , Xue Chunmei , Kong Le , Li Ruining , Xu Zhigang , Hua Jian
Published: February 2020

We report here the interactive effects of three light qualities (white, red and blue) and three growth temperatures (16�C, 22�C and 28�C) on rosette growth, hypocotyl elongation and disease resistance in Arabidopsis thaliana. While an increase in temperature promotes hypocotyl elongation irrespective of light quality, the effects of temperature on rosette growth and disease resistance are dependent on light quality. Maximum rosette growth rate under white, red and blue light are observed at 28�C, 16�C and 22�C, respectively. The highest disease resistance is observed at 16�C under all three light conditions, but the highest susceptibility is observed at 28�C for white light and 22�C for red and blue light. Interestingly, rosette growth is inhibited by phytochrome B (PHYB) under blue light at 28�C and by cryptochromes (CRYs) under red light at 16�C. In addition, disease resistance is inhibited by PHYB under blue light and promoted by CRYs under red light. Therefore, this study reveals a complex interaction between light and temperature in modulating rosette growth and disease resistance as well as the contribution of PHYB and CRY to disease resistance.
Barriers and Facilitators to Optimal Neuropathic Pain Management: SCI Consumer, Significant Other, and Health Care Provider Perspectives
Authors: Widerstrom-Noga Eva , Anderson Kim D , Perez Salome , Martinez-Arizala Alberto , Calle-Coule Lindsey , Fleming Loriann
Published: February 2020

Objective

Persistent neuropathic pain is a common and often severe consequence of spinal cord injury (SCI). There is a critical need to better understand how to overcome barriers and promote facilitators to optimal pain management. The present study was designed to identify, from the perspectives of persons living with SCI, their significant others, and SCI health care professionals, the barriers and facilitators to optimal pain management for intense neuropathic pain.

Design

Qualitative interviews.

Setting

University laboratory.

Subjects

People with SCI who had experienced intense neuropathic pain for a minimum of a year (N = 15), their significant others (N = 15), and SCI health care providers (N = 15).

Methods

Qualitative interviews were recorded, transcribed, and analyzed based on grounded theory using ATLAS.ti software.

Results

Inadequate access to care, information, or pain management expertise were frequently perceived barriers to optimal pain management across all three groups. Another major barrier was SCI stakeholders’ concerns regarding the risks of adverse effects and addiction to pain medication. Facilitators included having a better understanding of pain and available treatment options, effective patient–provider communication, resilience, and access to nonpharmacological treatment options.

Conclusions

Managing intense neuropathic pain poses significant challenges after SCI. SCI stakeholders felt that accessible treatment options were limited and primarily focused on pain medications with minimal benefit but with significant risks for addiction and adverse effects. Actionable facilitators to optimal pain management after SCI include education regarding neuropathic pain and treatment options for all stakeholders, better communication regarding neuropathic pain among stakeholders, and improved patient access to nonpharmacological treatment options.
The political economy of pension reforms in Europe under financial stress
Authors: Guardiancich Igor , Guidi Mattia
Published: February 2020

Despite a substantially unchanged problem load in the last 20 years, EU Member States witnessed a recent surge in pension reforms. Since the Great Recession, external market and political pressures started outcompeting national politics in pension-related decisions. Employing European Commission data on major pension reforms during 2006–2015, we find that governments respond to higher risk premia charged by international financial actors. Macro-policy fundamentals, such as budget deficits, and micro-policy indicators, such as pension spending, instead, only signal the necessity to act. They trigger the reforms in the presence of EU conditionality, that is, in the presence of Excessive Deficit Procedures and Country-Specific Recommendations within the European Semester. These findings deepen our understanding of the Europeanization of social policy, contribute to the literature on the political economy of reforms and testify to the declining role of domestic factors in the politics of the welfare state.
Hybridization and hybrid zone stability between two lizards explained by population genetics and niche quantification
Authors: Cabaña Imanol , Chiaraviglio Margarita , Di Cola Valeria , Guisan Antoine , Broennimann Olivier , Gardenal Cristina N , Rivera Paula C
Published: February 2020

Understanding the factors that affect hybridization is an important issue in the study of species evolution. In this work, we analyse the genetic structure of two lizard species, Salvator merianae and Salvator rufescens, at a microscale within a climatic niche analysis framework, to reveal the main factors that contribute to the stability of their hybrid zone. We assess the effect of climate in hybridization by quantifying and decomposing the niche overlap of both species. Using a mitochondrial and a nuclear marker, we find that hybridization is frequent and is not restricted to the sympatric region. The gene flow is mainly from S. rufescens to S. merianae, with introgression into the range of S. merianae. Also, S. merianae would have long been present in the area, while S. rufescens appears to be a recent colonizer. The climate contributes to the population structure of S. merianae, but not to that of S. rufescens. The niches occupied by S. rufescens in the hybrid zone and the non-hybrid zone are similar, while the niches of S. merianae are different. Our results do not fit previous models of hybrid zone stability, suggesting the need to develop new models that consider the evolutionary factors that can differentially affect parental species and hybrids.
Helicobacter labacensis sp. nov., Helicobacter mehlei sp. nov., and Helicobacter vulpis sp. nov., isolated from gastric mucosa of red foxes (Vulpes vulpes)
Authors: Gruntar Igor , Papić Bojan , Pate Mateja , Zajc Urška , Ocepek Matjaž , Kušar Darja
Published: February 2020

Six

Helicobacter

-like isolates were recovered from 15 gastric mucosa samples of red foxes (Vulpes vulpes) shot by hunters in the surroundings of Ljubljana, Slovenia. Gram-negative, tightly coiled, intensely motile, 7–15 µm long and ≤1 µm wide bacteria grew on the biphasic blood agar plates. By using a genus-specific polymerase chain reaction (PCR), all isolates were confirmed as

Helicobacter

sp. and subsequently subjected to whole-genome sequencing (WGS). Five isolates showed a genome-wide average nucleotide identity (ANI) value of <95 % to the previously described

Helicobacter

species and one isolate was classified as

Helicobacter felis

. In the five unidentified isolates, the 16S rRNA gene sequence similarity to the type strains of all

Helicobacter

species ranged from 98.6 to 98.9 %. Their taxonomic status was established using a polyphasic taxonomic approach comprising the core genome-based phylogeny, morphological and phenotypic characteristics, including an analysis of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectra. Phylogeny revealed the existence of three novel and well-supported clusters, with

Helicobacter bizzozeronii

and

Helicobacter baculiformis

being the most closely related species. The isolates also differed from the previously described species in their MALDI-TOF profiles and some biochemical characteristics. In conclusion, the data presented herein indicate that the obtained isolates, excluding

H. felis

isolate, represent three novel

Helicobacter

species, for which the names Helicobacter labacensis sp. nov., Helicobacter mehlei sp. nov., and Helicobacter vulpis sp. nov. are proposed, with isolates L9T (=DSM 108823T=CRBIP 111719T), L15T (=DSM 108730T=CCUG 72910T) and L2T (=DSM 108727T=CCUG 72909T) as type strains, respectively.