bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of Learning Machines for Turboshaft Engine Gas Path Fault Pattern Recognition
Authors: Zhao Shuai , Huang Jinquan , Lu Feng
Published: February 2020

Since the operating environment of a turboshaft engine is complex and harsh, gas path components are easily damaged. It is quite important of gas path fault diagnosis for turboshaft engine from the huge accumulated data. The paper presents the data-driven ways of learning machine algorithms for gas path fault diagnosis of the engine and the performance comparisons. Various Extreme Learning Machine (ELM), including basic ELM, Kernel ELM (KELM) and Multiple Layer KELM (MLKELM), are involved. Besides, the Deep Belief Network (DBN) as one of the deep learning machines is also employed to recognize fault patterns. The simulation is carried out on a turboshaft engine with typical gas path fault modes. The results show that the MLKELM and DBN provide better classification accuracy than the ELM and KELM, and the DBN consumes less training time compared to the MLKELM.
Optimal Configuration of Fault Current Limiter Based on Multi-objective Decision
Authors: Mo Wenxiong , Wang Yong , Chen Jun , Qiao Shengya , Zhu Lu , Fu Rong
Published: February 2020

To perfect the application of the fault current limiter in grid and improve the use efficiency, an optimal configuration method of fault current limiter based on multi-objective decision is proposed. Firstly, use rate of current change to select alternative branches, then taking the cost and current-limiting effect of fault current limiter as the targets, considering installation location, quantity of fault current limiter comprehensively, using α-method to determine the weight coefficient, establish multi-objective optimization model, and use immune algorithm to obtain the optimal scheme of branch installation. Next, by comparing the configuration of fault current limiter in the bus connection, the best configuration scheme is obtained. Finally, this method is verified by analyzing the IEEE39 node standard network.
Dynamic Electricity Price Guidance Analysis of Urban Electric Vehicle Based on Actual Data Drive
Authors: Duanchao Li , Han Su , Haiwei Wang
Published: February 2020

Establishing a dynamic electricity price to guide the charging behavior of car owners can better help electric vehicles (EV) to participate in peak shaving and valley filling of the grid. On the basis of this, a dynamic electricity price mechanism for electric vehicle charging stations in city was proposed in this paper.It was aimed at the distribution network where residential areas are located and mean to improve the ability of EV to cut peaks and fill valleys. Firstly, the load characteristics of residential areas were analyzed, in addition, the load status of the distribution network in the area before and after the EV charging station connected in were compared. Secondly, according to the proposed dynamic electricity price calculation process and related function based on the TOU (time-of-use) electricity price for electric vehicle charging station, the dynamic price of the day was established, then in order to predict the power load after the dynamic electricity price is implemented, the corresponding model based on the residential load elastic demand matrix was established. Finally, taking the actual data of a certain district near residential area in Anhui province and an electric vehicle charging station as an example, formulated the targeted dynamic electricity price and further verified the feasibility and effectiveness of the study.
Composition design of PMN-PH-PT piezoelectric ceramics for high-temperature actuator applications
Authors: Zhu Rongfeng , Fang Bijun , Zhang Shuai , Lu Xiaolong , Ding Jianning
Published: February 2020

High-Curie temperature (Tm) piezoelectric ceramics 0.15Pb(Mg1/3Nb2/3)O3-xPbHfO3-(0.85-x)PbTiO3 (0.15PMN-xPH-(0.85-x)PT, x = 0.36, 0.38, 0.39, 0.40, 0.42, 0.15PMN-PH-PT) were synthesized by the solid-state reaction method via the columbite precursor route. The synthesized 0.15PMN-PH-PT ceramics exhibit pure perovskite structure with compositions locate near the morphotropic phase boundary (MPB), where the rhombohedral phase and the tetragonal phase coexist. The sintered samples present high densification, in which the 0.15Pb(Mg1/3Nb2/3)O3-0.38PbHfO3-0.47PbTiO3 (0.15PMN-0.38PH-0.47PT) ceramics present the highest relative density, being 97.76%. The dielectric performance-temperature curves measured at different frequencies, the Curie-Weiss law fitting and the quadratic law fitting indicate that the ferroelectric phase transition from ferroelectric phase to paraelectric phase occurred at T0 in the 0.15PMN-PH-PT ceramics is driven by the displacive phase transition, and the 0.15PMN-PH-PT ceramics belong to normal ferroelectrics with diffused phase transition characteristic. Due to the MPB effect and high relative density, the 0.15PMN-0.38PH-0.47PT ceramics exhibit the best integral electrical properties, excellent thermal stability and large electric field induced strain, which present prospect promising for actuator applications under elevated environmental temperatures.
Wavefunctions for ground state 4f3 6s2 configuration of praseodymium to calculate energy of fine levels and other spectroscopic quantities
Authors: Zafar Roohi , Javaid Saba , Uddin Zaheer
Published: February 2020

Wave functions for terms with the same orbital angular momentum L and spin angular momentum S, but different parents can be written as a linear combination of the pure parentage wave functions. These wavefunctions are important because various spectroscopic quantities e.g. energy and transition probability can be calculated with the help of these wavefunctions. In this study we present 46 wavefunctions of seventeen terms (2P,2D, 2F, 2G, 2H, 2I, 2K, 2L, 4S, 4D, 4F, 4G, 4I,( 2D, 2F, 2G, 2H) are repeated terms, all terms have seniorty number 3 except 2F whose seniorty number is 1) of

4

f

3

6

s

2

configuration of Pr I, with seven parents (1S, 1D, 1G, 1I, 3P, 3F, 3H) belonging to

f

2

.

Some of the wavefunctions are non-orthogonal as they belong to same term symbol, having different seniority number. Gram-Schmidt procedure was used to make them orthogonal.
Ventricular repolarization abnormalities: the electrocardiographic track of cardiac tumoural involvement in an infant with tuberous sclerosis complex. A case report
Authors: Facin Mirella , Pastore Carlos Alberto , Samesima Nelson , Pereira Filho Horacio Gomes
Published: February 2020

Background

Primary cardiac tumours are rare in children. Against this backdrop, Doppler echocardiogram is the main diagnostic procedure, while electrocardiogram (ECG) usually plays a secondary role, by detecting tumoural consequences as cardiac arrhythmias and chambers overload. We describe a case where an electrocardiographic sign was the cornerstone to diagnosis and surveillance of an infant with a cardiac rhabdomyoma.

Case summary

A female infant was referred for cardiac evaluation to elucidate an electrocardiographic abnormality, detected during investigation of seizures. She had recently been diagnosed with epilepsy and was under three different anticonvulsants for appropriate control. Cardiovascular symptoms were absent. Skin inspection revealed hypochromic macules. Respiratory and cardiovascular examinations were normal, as well as laboratorial tests and chest radiography. Electrocardiogram (ECG) showed dome-shaped ST-segment elevation in V2 and V3. Transthoracic echocardiogram unveiled a single hyper-echogenic node (0.4 cm2) in the interventricular septum. Cardiac chambers had normal size and function and Doppler analysis was also normal. No specific medication was used to treat the tumour. During follow-up, she remained free of cardiac symptoms. Eighteen months after her first visit to the cardiologist, routine clinical assessment, ECG, and transthoracic Doppler echocardiogram normal results stated the spontaneous and complete involution of the tumoural lesion.

Discussion

Convex ST-segment elevation, generally related to myocardial injury, is unusual in paediatric patients. Once it occurs in asymptomatic individuals within this age bracket, exclusion of cardiac tumours is mandatory. However, data regarding the accuracy of such electrocardiographic marker in this clinical setting are still to be defined.
Total variation multiscale estimators for linear inverse problems
Authors: del Álamo Miguel , Munk Axel
Published: February 2020

Even though the statistical theory of linear inverse problems is a well-studied topic, certain relevant cases remain open. Among these is the estimation of functions of bounded variation ($BV$), meaning $L^1$ functions on a $d$-dimensional domain whose weak first derivatives are finite Radon measures. The estimation of $BV$ functions is relevant in many applications, since it involves minimal smoothness assumptions and gives simplified, interpretable cartoonized reconstructions. In this paper, we propose a novel technique for estimating $BV$ functions in an inverse problem setting and provide theoretical guaranties by showing that the proposed estimator is minimax optimal up to logarithms with respect to the $L^q$-risk, for any $q\in [1,\infty )$. This is to the best of our knowledge the first convergence result for $BV$ functions in inverse problems in dimension $d\geq 2$, and it extends the results of Donoho (1995, Appl. Comput. Harmon. Anal., 2, 101–126) in $d=1$. Furthermore, our analysis unravels a novel regime for large $q$ in which the minimax rate is slower than $n^{-1/(d+2\beta +2)}$, where $\beta$ is the degree of ill-posedness: our analysis shows that this slower rate arises from the low smoothness of $BV$ functions. The proposed estimator combines variational regularization techniques with the wavelet-vaguelette decomposition of operators.
Polarography as an Analytical Tool
Authors: Taylor John K
Published: February 2020

Polarography is a useful analytical tool for determining many substances in solutions at small concentrations, and is frequently applied to analysis of minor constituents. Conventional polarography employs a dropping mercury electrode, can measure solutions in concentrations ranging from 10-2 to 10-5M, and requires only a few tenths of ml for analysis.

Because of the difficulty of obtaining diffusion control in practice, methods are comparative and involve empirical calibrations with standard solutions. Practical tolerances have been worked out to insure that results are reliable to 2 relative per cent. Interferences have been lessened by several means, e.g., complexing, separation by electrolysis at controlled potential, selective extraction, and improvements in circuitry to permit use of relatively dilute supporting electrolytes. Modified polarographic methods include solid electrodes, derivative polarography, differential polarography, cathode ray polarography, anodic stripping polarography, and oscillographic polarography.
Fluorometric Method for the Determination of Amprolium in Feeds
Authors: Kaxora J , Szalkowski C R
Published: February 2020

A fluorometric method for the analysis of amprolium in feeds is presented, the sensitivity, speeificity, and reproducibility of which are equivalent to the AOAC 2,7-napiithalenediol colorimetric method.

Reduction in extraction time, stability of reagents, and simplification of cleanup shorten the time for analysis by more than 50%. The method involves extraction with 5% aqueous trichloroacetic acid solution; development of a fluorophor with 30% aqueous sodium hydroxide, 5% aqueous silver nitrate, and 2% aqueous potassium ferricyanide; and measurement of fluorescence on a suitable photofluorometer. Various commercial unmedicated feeds gave apparent drug concentrations of less than 1 ppm. The same feeds, blended with amprolium at different levels, showed recoveries of 98 to 107%. No appreciable interference from other drugs was noted in the analysis for amprolium. However, bias was evident when antibiotics, except procaine penicillin and chlortetracycline, were mixed with amprolium. The method is applicable to feeds down to the 40 ppm level of amprolium.
Thiabendazole in Feeds
Authors: Szalkowski C R
Published: February 2020

A method for thiabendazole, 2-(4’-thiazolyl)-benzimidazole, was studied collaboratively. The thiabendazole is extracted from the feed with dilute hydrochloric acid, and any interferences are removed by adjusting the extract to pH 6-8 and extracting with chloroform. The thiabendazole is re-extracted with dilute hydrochloric acid; the acid solution is treated with p-phenylenediamine and reduced with zinc dust. Oxidation with ferric sulfate yields a blue complex which is extracted with butanol and measured at 600 mμ. Unmedicated commercial feeds assayed by this method show an apparent thiabendazole content of 0.2—2 ppm, indicating absence of serious interference. In studies of 20 other drugs added to feeds, only nithiazide, Enheptin, and sulfathiazole interfere. The method is recommended for adoption as official, first action.
Collaborative Comparison of Colorimetric and Potentiometric Methods for Parathion and Methyl Parathion in Formulations
Authors: Helrich Kenneth
Published: February 2020

A collaborative study was conducted to compare the official volumetric method for parathion with the first action colorimetric method, as revised. Two samples of 15% powders were tested. Simultaneously one sample of methyl parathion was submitted to each collaborator for analysis by the above methods and by an infrared procedure. Based on statistical analysis of collaborative results, the revised colorimetric method is recommended for adoption as official, final action; further study of methods for methyl parathion is considered necessary.
Titrimetric and Electro-deposition Methods for Determination of Copper Naphthenate
Authors: Hiatt Virgil G
Published: February 2020

A titrimetric and an electro-deposition method for copper naphthenate were studied collaboratively. The titrimetric method involves shaking the sample with KI and ammonium bifluoride in aqueous solution and titrating the liberated iodine with standard thiosulfate solution. The electro-deposition method involves extracting the sample with (1 + 4) HNO3 and petroleum ether, and electrolyzing the solution at 2 amps. The titrimetric method is accurate and reproducible; the electro-deposition method showed over-all negative bias.
Chlorine Analysis by the Schoniger Oxygen Flask
Authors: Bontoyan Warren R
Published: February 2020

Preliminary study of the Schoniger oxygen flask method for chlorine in pesticides gave promising results. Of the four pesticides studied, combustion of DDT and HEOD was incomplete; combustion of chlordane and iso-octyl ester of 2,4,5-T was complete or nearly so. Collaborative study is planned.
Chromatographic Determination of Sulfoxide
Authors: Haus Joseph B , Manolev Lazar , Price Robert W
Published: February 2020

A new method for the assay of technical sulfoxide involves separation of the sulfoxide by column chromatography on silicic acid by two successive eluting solutions, 2% acetone in chloroform and 10% acetone in chloroform, followed by ultraviolet spectrophotometry of the eluate at 256 and 288 mμ. Isosafrole, the thioether, and the sulfone are separated by the column.
Determination of Sevin Insecticide Residues in Fruits and Vegetables
Authors: Johnson D P
Published: February 2020

Collaborative study of a method for Sevin insecticide residues was repeated with apples and lettuce as test crops. The method is based on alkaline hydrolysis of Sevin and colorimetric determination of the resulting 1-naphthol with p-nitrobenzenediazonium fluoborate as chromogenic agent. Data from 5 collaborators were in good agreement with an average recovery of 87.8% at 2 concentration levels. It is recommended that the method be adopted as official, first action.
Screening Procedure for Organothiophosphate Pesticide Residues on Fruits and Vegetables by Microcoulometric Gas Chromatography
Authors: Nelson Richard C
Published: February 2020

The Mills-Onley-Gaither procedure for extraction and cleanup of chlorinated pesticide residues in fruits and vegetables was adapted for use in organothiophosphate residue screening. The acetonitrile extraction-petroleum ether shakeout was employed, and up to 5 g of sample was injected into a microcoulometric gas chromatograph with no further cleanup. The microplatinum cell, which titrates only sulfur, was used. Recoveries from “spiked” fruits and vegetables (average of 2—3 determinations) were: Systox, 33%; Delnav, 68%; Diazinon, 86%; Di-Syston, 85%; methyl parathion, 82%; parathion, 88%; malathion, 71%; ethion, 107%; Trithion, 94%; EPN, 78%. Satisfactory baselines were obtained on plums, peaches, cherries, grapes, carrots, lettuce, cabbage, cauliflower, asparagus, and celery. Standard parent compounds only were studied.
A Flame Ionization Detector Highly Selective and Sensitive to Phosphorus—A Sodium Thermionic Detector
Authors: Giuffrida Laupa
Published: February 2020

A selective detector for use in a gas chromatography system for the detection of organophosphate pesticide residues in foods has been developed and investigated. The device consists of a conventional detector with a coat of a sodium salt fused onto the electrode. There are two requirements: sodium must be present and it must be heated. This sodium thermionic detector is highly selective in response to phosphorus in an organic compound. Other atoms generate some response also, but the relative sensitivity to phosphorus is so great that the sensitivity of the detector can be adjusted to measure essentially only phosphorus. The detector also responds selectively to halides but to a much lesser degree. The detector can detect and measure both organophosphate and chlorinated pesticide residues in a sample extract.
Paper Chromatographic Analysis of Chlorophenoxy Acids and Esters in Wheat
Authors: Yip George
Published: February 2020

2,4-D, MCP, 2,4-DB, 2,4,5-T, 2,4,5-TP, and esters of 2,4-D can be detected as residues on wheat by paper chromatography after cleanup. The cleaned up samples are also suitable for analysis by gas-liquid chromatography. Rf values are presented for each chlorophenoxy acid and ester. Dimethylformamide in ether (35%) as immobile phase and 2,2,4-trimethylpentane as mobile phase give better resolution of the methylated acids than 10% mineral oil in ether (immobile phase) and 50% acetonitrile in water (mobile phase).
Collaborative Studies on Methods for Nitrate and Nitrite in Meat
Authors: Landmann W A , Worland M C
Published: February 2020

Results of collaborative studies on three nitrate and two nitrite methods were examined by statistical procedures of Youden. The FeCl2 procedure was again found lo be subject to extreme bias. A modified procedure employing m-xylenol gave results which were somewhat improved in precision over previous tests. However, the procedure was still subject to systematic errors and rather large random errors resulting in only fair precision. A direct nitrate method based on color development with brucine was highly variable and unsatisfactory. The colorimetric procedure for nitrite, using Griess reagent, appeared to be relatively free of bias, but had only fair precision, and its usefulness is limited by the high standard deviation. An iodometric procedure, based on liberation of iodine from KI solution by the nitrite and titration with thiosulfate, proved to be quite precise and subject only to small bias, within acceptable limits of procedure. This method was far superior to the colorimetric method and should be adopted as official, first action for dry cure mix and pickle mix.
A Study of the Ammonium Phosphomolybdate Method for P2O5 by National Plant Food Institute's Phosphorus Task Force
Authors: Harwell A O , Parks K L , Harwood W W , Barker J E
Published: February 2020

The volumetric ammonium molybdate method for P2O5 has been studied intensively. Accuracy and precision are improved by adhering to more explicit directions for application. The method is applicable to fertilizer materials and is considered "rugged." End point identification and solution standardizat ion are important steps, requiring the exercise of care and control.
Collaborative Studies of Official Methods for Determining Water in Fertilizers
Authors: Caro Joseph H
Published: February 2020

The oven method for total water was studied by 18 collaborators and the vacuum desiccation method for free water by 13 others. Eleven materials were tested in each study, six of which were common to both. In the oven method, precision of results was only fair, but much of the variability could be attributed to causes other than the imprecision of the method. When the findings were corrected to show only the latter, the method yielded precise results on 8 of the 11 samples. Laboratories using mechanical-convection ovens agreed well with those employing gravity-convection types. Three collaborators submitted results that were biased, as judged by the Youden ranking method. In the vacuum desiccator study, collaborators agreed well on all but three materials; the spread of these results was ascribed to in-sample variability. One collaborator exhibited bias, probably because of use of P2O5 rather than Mg(C104)2 as desiccant. Several obviously inaccurate results were submitted by collaborators, pointing up the need to maintain a disciplined technique even in this simple method.
Determination of Calcium and Magnesium in Fertilizers by EDTA Titrations: A Collaborative Study
Authors: Smith John B , Manning Peter B
Published: February 2020

Collaborative analyses of nine fertilizers by eight analysts at seven laboratories demonstrated that the EDTA method for magnesium is equally accurate and more precise when compared with the longer official methods. Neither the EDTA method nor official method 2.085 was satisfactory for all samples. The EDTA method for magnesium will not tolerate more than 0.25% of manganese or zinc.
Effect of Extraction Time on Citrate-Insoluble P2O5 Content of Fertilizer
Authors: Gehrke Charles W , Kramer George H
Published: February 2020

Twenty-four commercial fertilizers representing different types and grades and different manufacturing processes were used to evaluate the effect on CI P2O5 of digestion time at 65°C with continuous agitation. The data show that for mixed fertilizers and straight materials, all water and citrate-soluble phosphorus was extracted within 60 minutes of digestion, with two exceptions: Further solubilization of CI P2Os occurred in samples of tricalcium phosphate and ammoniated triple superphosphate samples for digestion times of 2— 3 hours.
Determination of Pentaerythritol Tetranitrate in the Presence of Meprobamate
Authors: Rosenstein Jack
Published: February 2020

Use of phenoldisulfonic acid was found to be applicable to pentaerythritol tetranitrate determination with or without meprobamate being present. Recoveries from collaborative samples with or without meprobamate were 100 £ 3% of the theoretical amount.
Determination of Choline in Feeds
Authors: Lim F , Schall E D
Published: February 2020

The "free" and "bound" forms of choline were determined in feeds by a rapid method in which extraction and hydrolysis were accomplished simultaneously with a barium hydroxidemethanol-chloroform mixture. The choline was isolated from the hydrolysate by adsorption on a Florisil column. Passing ammonium reineckate through the column formed the choline reineckate which appeared as a pink band after excess reagent was washed out. The concentration of the choline was determined by eluting the reineckate band and measuring the absorbance at 526 mμ. Recoveries of added choline ranged from 98.9 to 100.8%.
Basic Feed Microscopy
Authors: Smith C Tyson
Published: February 2020

Collaborative results are presented on a basic procedvire for feed microscopy using either the stereoscopic or high power microscope to identify vegetable tissues, animal tissues, and major mineral constituents. A poultry grower mash and a dairy concentrate were studied; each sample contained ingredients conforming to the definitions of the Association of American Feed Control Officials. The identifications of the unknown ingredients by the collaborators were reasonably reliable, and the method is recommended for adoption as official, first action.
Collaborative Study of Colorimetric Methods for Phosphorus in Feeds
Authors: Heckman Mary
Published: February 2020

Six feed samples of varying phosphorus content and with calcium/phosphorus ratios of 0.5— 2.0 were distributed. Eleven laboratories compared the official volumetric method (22.061) with the molybdenum blue method studied in 1962. Twelve laboratories compared 22.061 with Parks and Dunn's colorimetric molybdovanadate method now used for fertilizers. Means for all methods show excellent agreement. Statistical analysis by Youden's formula shows marked superiority of the molybdovanadate method over the molybdenum blue method.
Rapid Infrared Method for Toxaphene in Animal Dips and Sprays
Authors: Czech Fred P
Published: February 2020

An infrared spectrophotometric method has been developed for the determination of toxaphene in aqueous emulsions used for the eradication of ectoparasites in livestock. The active ingredient is "salted-out" of emulsion with sodium chloride and extracted with carbon tetrachloride, and an infrared spectrum is taken of the latter extract. Toxaphene concentration is obtained from its characteristic absorption peak at 1303 cm-1 by the baseline method. The infrared method has the advantages of speed, simplicity, and, especially, specificity over chemical procedures.
Enzymatic Determination of Carbon Dioxide in Lightly Carbonated Wine—1963 Collaborative Study
Authors: Morrison Robert L
Published: February 2020

The titrimetric method for determining carbon dioxide in wine, using carbonic anhydrase, was studied collaboratively for the second year. Sample preparation was improved, and two modifications were made in the apparatus: a 5 ml instead of a 10 ml buret and a 25—30 ml automatic pipet instead of a 50 ml buret. Results were good, and it is recommended that the method be adopted as official, first action.
Quantitative Methods for Trace Amounts of Polyvinylpyrrolidone
Authors: Shiraeff D A
Published: February 2020

Two approaches were used for a simple procedure for quantitative estimation of polyvinylpyrrolidone: I. PVP forms complexes with textile dyes, which can be identified by paper chromatography. When PVP is added to a chromatographing solvent, the spread of a spot of dye placed on a paper strip is a function of PVP concentration in the solvent. Pyramine Orange 2R and Congo Red were used in the test. II. At concentrations of perchloric acid greater than 1.6-1.7%, PVP falls out of solution and forms a finely dispersed precipitate like a cloud. The clouding is proportional to PVP concentration and can be measured by a nephelometer or spectrophotometer.
Removal of Urea from Corn by the Steeping Process of Wet Corn Milling
Authors: Nicholson J F , Harris Kenton L
Published: February 2020

To test the removal of urine from corn by the corn steeping process, urea containing C-14 was added to corn in four different ways. Radiation present after steeping demonstrated that some of the added C-14 remained in the corn, indicating that some urine persists through the corn steeping process. When added to the insect exit hole, the greatest amount remained unremoved by steeping (average of 2.9%). Amounts above radiation normal to leached corn (0.2 counts/min.) also remained in one instance when the radioactive urea was placed on the endosperm and in one or two instances when it was allowed to enter at the germ end.
Assay of Oil-Soluble Vitamins. Part I. Vitamin A and Carotene: Suggestions for Improving Assay
Authors: Deutsch M J , Jones S W , Wilkie J B , Duffy D , Loy H W
Published: February 2020

The adaptation of official methods to the assay of vitamin A in many commercial products has required modifications in the apparatus used and improvements in assay techniques. These modifications increased the number of routine samples that are screened per day from three to eight, with a corresponding increase in per cent recovery and degree of reproducibility. The most important modifications were installation of equipment to permit handling of more samples at a time, changes in volumes and concentrations of solutions to improve separations, and use of an internal standard in the antimony trichloride method for the assay of vitamin A.
Collaborative Study of Microbiological Assay for Folic Acid in Food
Authors: Flynn Laura M
Published: February 2020

The extraction and microbiological determination of folic acid in foods was studied collaboratively. Four samples and four extraction procedures were used. Extracts were assayed for folic acid activity with L. casei and S. faecalis, and chick assays were also made on the samples. The four extraction procedures were: (A) Incubating 4 hours with chick pancreas at 37 °C after autoclaving 15 min. at 15 lb in 0.2M pH 7.2 phosphate buffer and cooling; (B) autoclaving 30 min. at 15 lb in potassium ascorbate (pH 6.0, 6 mg/ml); (C) incubating 4 hours with chick pancreas enzyme after autoclaving 15 min. at 15 lb in 0.2M pH 8 phosphate buffer, cooling, and adding potassium ascorbate (20 mg/ml, pH 6) in volume equal to the phosphate buffer; and (D) autolyzing in incubator 4 hours at 37 °C in mixture of equal volumes of potassium ascorbate (20 mg/ml, pH 6) and 0.2M phosphate buffer, pH 8.0. The highest values were obtained with L. casei in extracts containing potassium ascorbate. A rough estimation of the types of folic acid derivative in each extract could be made by comparing values obtained in the various extracts with each organism. Collaborators’ results by chick assay agreed fairly well with those by microbiological assay, but further work is needed to standardize the extractions and both types of assays.
Analysis of Insecticides in Aqueous Emulsions Used in Livestock Dips and Sprays: General Infrared Method
Authors: Czech Fred P
Published: February 2020

An infrared spectrophotometry method can be widely applied as a general procedure for analysis of insecticides in aqueous emulsions used to eradicate ectoparasites in livestock. Analytical procedures are given for Delnav, Ciodrin, lindane, and toxaphene-lindane mixture. The method is rapid, simple, precise, versatile, generally free from interference, and unequivocally specific. It is recommended as a universal first approach to analysis of insecticides in animal dip and spray emulsions.
A Cold Bath and Stirring Assembly for Low Temperature Precipitation of Fat
Authors: Mccully K A , mckinley W P
Published: February 2020

A cold bath and stirring assembly are illustrated for use in the precipitation of fat at a low temperature. This precipitation of fat is useful as a cleanup procedure for the determination of chlorinated pesticide residues.
A Simple Method for the Detection of Benzo[a]pyrene in Smoked Foods
Authors: Genest C , Smith D M
Published: February 2020

Benzo[a]pyrene can be used as an index of carcinogens in smoke. A simple and rapid method has been developed for determining this substance. The dried food was extracted with ra-hexane, the hexane was then extracted with dimethyl sulfoxide, and the polynuclear hydrocarbon was displaced from this solvent into benzene by water. The benzene extract was reduced to a small volume and an aliquot was spotted on a thin-layer chromatographic plate beside spots of a standard benzo[a]pyrene solution. The plate was chroma tographed with 2,2,4-trimethyl pentane:benzene (97:3). When observed under ultraviolet light at 3660 Å, 0.002 μg of pure benzo[a]pyrene could be found and the addition of 0.01—0.05 ppm to unsmoked foods could be detected. No smoked food examined contained this level of benzo-[a]pyrene.
An Improved Ammonium Molybdophosphate Method for Phosphorus in Fertilizers
Authors: Brabson J A , Johnson F J , WILLIARD J W , Burch W G
Published: February 2020

The official volumetric method for phosphorus in fertilizers was modified to improve its accuracy and precision. Sulfate interference is eliminated by addition of excess nitric acid before precipitation of the molybdophosphate. The precipitate is filtered on a glassfiber pad, and when it is dissolved in alkali, formaldehyde is added to complex the ammonia; a mixed indicator (methyl green-phenolphthalein) is used that changes color at the equivalence point. The modified method passed Youden’s ruggedness test and gave results in excellent agreement with those of the gravimetric quinolinium method in analyses of standard phosphate rocks, primary phosphate standards, and fertilizers.
A Preliminary Investigation Into the Quantitative Determination of Organophosphorus Pesticide Residues by Conversion to Orthophosphate Ion
Authors: Getz Melvin E
Published: February 2020

Organophosphate pesticides are converted to orthophosphate ion, by reaction with a dilute solution of ammonium persulfate. This method shortens the reaction time and eliminates the handling of strong acids necessary for conventional digestion procedures; 0.1 μg of P is detected, which is equivalent to approximately 1 μg of pesticide.
Colorimetric Determination of Residues of the Dithiolane Insecticides in Cottonseed and on Cotton Foliage
Authors: Blinn Roger C , Boyd John E
Published: February 2020

A colorimetric procedure has been devised to determine residues of the dithiolane insecticides, 2-diethoxyphos-phinothioylimino-1,3-dithiolane (I) and 2-diethoxyphosphinylimino-1,3-dithiolane (II), in cottonseed and on cotton foliage. The chromogenic reaction is based on the acid hydrolysis of the dithiolane insecticides to 2-imino-1,3-dithiolane, which is converted by treatment with alkali to thiocyanate. The thiocyanate is converted to cyanogen bromide and then reacted with benzidine-in-pyridine solution to form an intense red solution with absorbance maximum at 530 mμ. Recoveries of I and 11 from cottonseed averaged 83 ± 5% and 68 ± 4% in the range 0.1-1 ppm, with background values of 0.04 ± 0.01 ppm; recoveries from cotton foliage averaged 79 ± 7% and 84 ± 7%, respectively, for I and II, with background values of 0.02 ± 0.01 ppm.
Quantitative Determination of Vanillin and Ethyl Vanillin in Flavors by Paper Chromatography
Authors: Fitelson J
Published: February 2020

Previous methods for estimating vanillin and ethyl vanillin in mixtures were long and complicated. However, this paper presents a simple chromatographic separation and quantitative determination of these aromatics, using Mitchell equipment for paper chromatography and 8 × 8” papers. Development for 2 hours separates the compounds adequately; they are then extracted and measured by absorbances at 348 mμ in alkaline solution. Recoveries of added vanillin and ethyl vanillin to vanilla extract are excellent. Aside from normal manipulative errors, the only significant inaccuracy is caused by the small amount of natural p-hy-droxybenzaldehyde in vanilla (usually equivalent to about 5% of the vanillin content). The method does not separate p-hydroxybenzaldehyde and vanillin. Total errors in the method do not exceed 0.01%. Comparison of the method with the two AOAC methods for vanillin shows that the paper chromatographic method gives results close to those by the ultraviolet absorption method, in most cases, and significantly lower results than the photometric method, which is known to give erroneously high results.
Ultraviolet Spectrophotometric Method for Ronnel in Feeds
Authors: Gehrt Albert J
Published: February 2020

The ultraviolet spectrophotometric method for Ronnel in feed mixtures, presented at the 1963 AOAC meeting, was studied further at levels of 0.015–0.6% Ronnel by 10 collaborators to test the accuracy and reproducibility of the method by vising reagents free from abnormal ultraviolet absorbance. The variety of feed ingredients was increased to include milo, barley, and alfalfa in addition to those used in the 1963 study. Ronnel is extracted from the sample with methanol-petroleum ether and hydrolyzed to the 2,4,5-trichlorophenate. After solvent evaporation, the residue is dissolved in water, the pH is adjusted and buffered at 7.0, calcium chloride solution is added, and the mixture is steam distilled. The 2,4,5-trichlorophenol in the steam distillate is extracted with iso-octane and measured spectrophotometrically. All collaborators obtained good results; therefore, the Associate Referee recommends that the method be adopted as official, first action. Experimental studies showed that 2,4,5-trichlorophenol can be separated from Ronnel by ion exchange. This will be studied collaboratively next year.
Extraction and Estimation of Polycyclic Aromatic Hydrocarbons Added to Milk
Authors: Howard John W , Teague Robert T
Published: February 2020

Polycyclic aromatic hydrocarbons added to milk are extracted directly from the milk with a hydrocarbon solvent under alkaline conditions. A partition step between the hydrocarbon solvent and dimethyl sulfoxide, followed by paper chromatography, is then employed to reduce interfering background material extracted from the milk. Ultraviolet spectral analysis is used to estimate the type and concentration of polycyclic compounds. Recoveries of 8 polynuclear hydrocarbons, added to one pint of milk at levels of about 2 and 4 ppb, ranged from 63 to 90%.
Determination of Minor Nutrients in Fertilizers by Atomic Absorption Spectrophotometry
Authors: McBride C H
Published: February 2020

A general atomic absorption spectrophotometric method for the determination of copper, iron, magnesium, manganese, and zinc in commercial fertilizers and raw materials is presented. The method has been subjected to ruggedness and collaborative tests and is shown to be simple, rapid, and acceptably precise. Its adoption as official, first action is recommended.
Determination of Cobalt in Fertilizers
Authors: Hodgson J F , Lazar Victor A
Published: February 2020

Cobalt in fertilizers was determined by a colorimetric method using 2-nitroso-l-naphthol. With this method the fertilizer is digested with a ternary acid mixture; cobalt is then extracted from a suitable aliquot into isoamyl acetate at pH 8.5 with an excess of 2-nitroso-l-naphthol. Excess dye and interferences are removed by successive washes with acid and base. A limited number of collaborator analyses indicate that agreement of results is not as satisfactory as might be expected with the major fertilizer constituents. However, collaborator agreement compares favorably with other methods of analyses accepted by the AOAC for Co. While the procedure is considered tedious by some collaborators, it is believed to be less tedious and less subject to interferences than other colorimetric methods available.
Collaborative Study of a Chemical Method for Chick Edema Factor in Fats and Fatty Acids
Authors: Higginbotham G R
Published: February 2020

The microcoulometric gas chromatographic method for detection of chick edema factor in fats and fatty acids was suhjected to a second collaborative study. Results were satisfactory, and it is recommended that the method be adopted as official, first action.
Evaluation of Methods for Identifying Fatty Acid Esters Separated by Gas Chromatography
Authors: Iverson John L , Firestone David , Eisner Jerome
Published: February 2020

Correct identification of component fatty acids is frequently difficult when determining fatty acid composition by the AOCS-AOAC gas chromatographic method. Fats and oils that contain a large number of components, such as butter, peanut, and marine oils, are particularly troublesome. The usefulness and limitations of (a) isothermal semilogarithmic plots, (b) retention time ratios, (c) programmed temperature semilogarithmic plots, and (d) variation of retention time with temperature are evaluated.
Fractionation of the Color of Pure Maple and Other Sirups by Gel Filtration
Authors: Stinson E E , Willits C O
Published: February 2020

The colorants of pure maple, cane and maple, refined cane sugar, and light brown sugar sirups were separated into two fractions, one of high- and the other of lowmolecular weights, by means of gel filtration.

The ratio of the amounts of high- to the low-molecular weight fractions of pure maple was the lowest of the four sirups and serves as a means of differentiation from these sirups. The color fraction ratio was highest for blended cane-maple sugar sirup.

Many maple sirups are also distinguished by a pink band formed on the gel filtration column.
Comparison of Methods for the Determination of Vanillin in Vanilla Extract
Authors: Smith D Morison
Published: February 2020

Vanillin was determined in vanilla extracts by standard colorimetric and ultraviolet spectrophotometric procedures. A comparison of the results by these methods and an assessment of the probable interferences led to the development of a new UV spectrophotometric method. This procedure is based vipon the difference in absorbance between alkaline and neutral solutions of the vanilla and can, by the use of a suitable equation, be used to determine both the vanillin and p-hydroxybenzaldehyde concentrations.
Determination of Fly Eggs and Maggots in Tomatoes and Tomato Products
Authors: Coulter Earl W
Published: February 2020

A sieving method has been developed to improve insect fragment recovery and reduce the percentage of eggs recovered without process from tomatoes and tomato products. The method is rapid, requires no specialized equipment, and uses an inexpensive and readily available reagent. Residues of all types of tomato products can be counted on one cloth. The method is adaptable to large samples. It is recommended that the sieving method be studied collaboratively.
UV Determination of Sulfoxide in Formulations
Authors: Haus J B , Manolev L , Price R W
Published: February 2020

A method for the assay of sulfoxide in insectieidal formulations involves separation of the sulfoxide from the other components by column chromatography on silicic acid with three successive eluting solutions: chloroform; 2% acetone in chloroform; and 10% acetone in chloroform. Sulfoxide is removed in the last eluate and is determined by ultraviolet spectrophotometry. Solvents, emulsifiers, pyrethrins, compounds related to sulfoxide, and other insecticides tested are separated by the column.
Sampling Commercial Feeds
Authors: Spruill C K
Published: February 2020

To determine if the accuracy of a sample is changed by taking 10 cores instead of 20 cores, a study was made of 260 samples of 10 cores and of 20 cores of bulk commercial feed, representing 130 different rail car loads. Very little difference was found in the protein, fat, and fiber content between the two sampling sizes. Based on the study, it is recommended that the official sampling procedure be amended to specify that at least 10 cores from different regions be collected in sampling bulk feeds.
Rapid Digestion and Cleanup of Animal Tissues for Pesticide Residue Analysis
Authors: Stanley Ronald L , LeFavoure Herbert T
Published: February 2020

A method is presented for the rapid digestion and cleanup of animal tissues for pesticide residue analysis. Animal tissues are digested by a perchloric-acetic acid mixture to destroy the cellular structure and quantitatively liberate the pesticide-containing fat. The fat is extracted in n-hexane and destroyed on a sulfuric acid-Celite column. The common chlorinated pesticides (except aldrin, dieldrin, and endrin) can then be determined by a colorimetric or chromatographic procedure.
Microanalytical Determination of Bromine, Chlorine, and Iodine by Oxygen Flask Combustion
Authors: Steyermark Al
Published: February 2020

Thirty collaborators participated in a study of the use of oxygen flask combustion for the microdeterminations of bromine, chlorine, and iodine in organic compounds. Generally, there was little difference in the precision of the various methods. Argentometric titration gave better results than did iodometric titration only in the case of bromine. The use of hydrazine sulfate gave better results in the case of iodine than when it was omitted; the same held true for hydrogen peroxide. It is recommended that the study be continued.
Ion Exchange Resin Separation and Flame Photometric Determination of Sodium, Potassium, Magnesium, Calcium, and Strontium
Authors: Breault Eugene A
Published: February 2020

The cation exchange separation of metallic chlorides by hydrochloric acid on an Amberlite CG-120 resin (200-400 mesh) column was investigated. Commercially available resin was used in the experiments after the “fines” were removed by several water washings. A resin column (24 cm long by 12 mm diameter) gave excellent separation of sodium and potassium, with a total volume of 500 ml of 0.5N HCI at a flow rate of 0.55 ml/min. The recovery of each metal was 100%. Elution of the other three metals required 1100 ml of liV HCl; separation was very good but recoveries were poor. AH of the metals were determined with a Beckman DU with photomultiplier and hydrogen-oxygen flame attachment.
Thin-Layer Chromatographic Determination of Carbaryl (Sevin) in Some Foods
Authors: Finocchiaro Josephine M , Benson Walter R
Published: February 2020

A thin-layer chromatographic method is described for the semiquantitative determination of the insecticide carbaryl. Acceptable recoveries ranging from 0.05 to 0.2 ppm have been obtained from nine crops. The Rf value of carbaryl ranged from 0.52 to 0.60 on aluminum oxide G plates.
Collaborative Study of Maleic Hydrazide Residue Analysis
Authors: Lane J R
Published: February 2020

The recoveries obtained from raw and processed food crops fortified with 10 μg or more of maleic hydrazide per analytical sample demonstrate that a wide range of concentrations of maleic hydrazide residues can be accurately determined. The test shows good reproducibility and agreement of data, considering the additional possible error of a blending at point of origin and reblending upon receipt by the collaborator, the lack of refrigeration, and the use of a single determination of the unknowns. The crops used included cranberries, onions, peaches, tobacco dust, and potatoes (whole, dehydrated mashed, frozen french fries, and potato chips). The average recoveries on these crops, fortified with 1.3–85 ppm, ranged from 70 to 92%.
Use of Detergents in Analysis of Fibrous Feeds. III. Study of Effects of Heating and Drying on Yield of Fiber and Lignin in Forages
Authors: Soest P J Van
Published: February 2020

Heat-drying of forages at temperatures above 50°C shows analytically significant increases in yield of lignin and fiber. The increased yield of acid-detergent fiber (ADF) can be accounted for largely by the production of artifact lignin via the non-enzymic browning reaction. Values for ADF and lignin in dried forages can be corrected on the basis of the nitrogen content of the ADF. The nitrogen content of the ADF is suggested as a sensitive assay for nonenzymic browning due to overheating of feeds.
Gas Chromatographic Determination of Sodium Benzoate in Meat
Authors: Nobe Benley , Stanley Ronald L
Published: February 2020

A method has been developed for the determination of sodium benzoate in meats by gas chromatography. The meat sample is digested in acetic and perchloric acids and extracted successively in acidic, basic, and again acidic solutions. The benzoate components contained in this extract arc quantitatively determined by flamc-ionization gas chromatography with a high degree of precision and sensitivity. The minimum limit for quantitative determination is about 11 ppm sodium benzoate in meat (based on a 9 g sample).
Collaborative Study on Assay of Sulfur Dioxide in Dried Fruit
Authors: Nury F S , Bolin H R
Published: February 2020

Sulfur dioxide analysis by official (Monier-Williams) methods was compared with a new colorimetric procedure for dried fruits. Dried peaches, pears, apples and golden raisins were the test materials. The colorimetric method was found to be neither more nor less variable than two official methods except in analysis of dried pears, took less time and was easier to perform than the official methods, and yielded satisfactory recovery of sulfur dioxide.