bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of phase composition on quality of ASN fertilizers
Authors: Štrbová Z , Jorík V , Kučera M
Published: January 2020

Ammonium Sulfate Nitrate (ASN) based fertilizers are very efficient fertilizers in modern agriculture. Designed to provide targeted nutrition and high yields, they combine the extended availability of Ammoniacal (NH4) and rapid effect of Nitrate Nitrogen (NO3) with the multiple agricultural benefits of Sulfur. Most of these products have some tendency to form agglomerates (caking) and dust during storage in a bulk of hundreds to thousands of tons. The severity of quality deterioration can be influenced by a number of factors, such as phase composition, moisture content, particle structure, mechanical strength, hygroscopic properties, product temperature, ambient conditions, storage time and pressure. ASN fertilizer is mainly a combination of the double salts 3AN·AS ((NH4)5(NO3)3SO4) and 2AN·AS ((NH4)4(NO3)2SO4). It is known that presence of these mixed salts has a strong impact on the quality of fertilizer. Seeing that X-ray Powder Diffraction analysis (XRPD) is commonly used to control the quality of industrially produced fertilizers, a new X-ray method has been developed. This new method is based on the determination of the ratio of the integral intensities of the diffraction lines of the 3AN·AS and 2AN·AS components. The ratio obtained by line profile analysis provides an effective screening test of the quality of fertilizer immediately after production. In accordance with ratio value it is possible to estimate quality changes of product during long-term storage.
Fatigue life of thermoset composite materials
Authors: Zaludek M , Rusnakova S , Kubisova M , Bilek O , Karvanis K
Published: January 2020

This article deals with the lifetime of laminated materials produced by different production technologies (hand lamination technology, vacuum bagging technology and prepreg technology with curing in the oven) during cyclic repeated bending stress. Like tested materials composite systems were chosen composite systems with epoxy matrix and carbon reinforcement (Kordcarbon CC200T, epoxy resin with trade name L285) and second composite epoxy system with glass reinforcement (Quadra-axial glass fabric, named Saertex Q-E-820, epoxy resin Biresin CR 82 and third prepreg systems (unidirectional prepreg, trade name Deltapreg VV430U-DT860W-39% and prepreg system with glass fabric VV320P_DT806R-37%). Fatigue tests were performed by cyclic bending loads during a three-point arrangement on a universal servo-hydraulic testing machine INSTRON 8871. Experimentally the number of cycles fracture of the material was determined at 90 % and 80 % of the maximum breaking load.
Influence of microstructure on fracture feature of Ti6Al4V alloy prepared by 3D printing
Authors: Losertová M , Kubeš V , Drápala J , Dostálová K , Sevostyanov M A , Di Cocco V , Iacoviello F
Published: January 2020

In this work, the Ti6Al4V specimens produced by selective laser melting were mechanically tested in non-heat treated condition and fracture surface features were compared with this one of the material prepared using conventional casting and forging. The results of the fractography observation for both types of the samples were explained on the base of the microstructure analysis. The fracture surface of selective laser melted specimens showed more brittle feature that was in relation with the microstructure composed almost fully of martensite as opposed to conventionally prepared alloy with bimodal (α + β) microstructure and more ductile character of fracture surfaces.
Structure and Properties of SWCNT-Modified CFRP
Authors: Burkov M V , Eremin A V
Published: January 2020

Structure and mechanical properties of CFRP modified by SWCNT with different content (0.1, 0.2 and 0.3 wt. %) have been studied in the present paper. The structural investigations include SEM imaging while the mechanical properties have been characterized via tensile and flexural tests. The main functional feature of such hybrid composite is an electrical conductivity, which has been also measured. Out-of-plane conductivity has been enhanced up to ∼66 S/m from dielectric unmodified CFRP. It has been shown that tensile properties stay almost unchanged, while flexural strength and modulus have increased by 22% and 16% correspondingly.
Application of Laser Welding in Car Bodies Manufacturing
Authors: Viňáš J , Brezinová J , Brezina J , Maruschak P , Panin S
Published: January 2020

The paper deals with a problem of laser welding of zinc-coated steel (DX53D+Z and DX54D+Z) plates. Experiments were carried out with the use of steel plates 0.8; 1.0; 1.3; and 1.75 mm thick. High power 2.5-2.9 kW CO2 laser was employed. CO2 was used as the shielded gas. The optimal parameters of welding for material under study were determined. The mechanical properties of welded joints were measured through the tensile loading and microhardness measurement. Tensile performances of the specimens fabricated at different welding rate and laser beam power were compared with that of the base material.
The Effect of Plastic Deformation on the Geometric Parameters of Nb-Ti-Based Superconducting Cable
Authors: Yntymakova A , Shlyakhova G
Published: January 2020

The current carrying capacity of a superconductor depends on its microstructure, that is, the shape, size and volume content of particles released during the decomposition of a solid solution. At the technological stage, it is necessary to ensure continuity of the process and a given density of micro defects. Therefore, the aim of this work was to assess and present the results of studies of the effect of plastic deformation (tension) on the structure of a multicore superconductor based on Nb-Ti alloy. Mechanical tests were carried out for uniaxial tension to failure on a Walter + Bai AG LFM-125 testing machine (maximum force up to 125 kN). The internal structure of the sample at the fracture site after the sample preparation was studied using a Neophot-21 optical microscope. The effect of deformation on the geometric parameters of Nb-Ti fibers was studied. Sample preparation included thin sections, polishing and etching.
Influence of a Delamination Type Defect on the Operational Life of a Sound-Absorbing Structure with a Honeycomb Filler
Authors: Anoshkin A N , Pisarev P V , Ermakov D A
Published: January 2020

In the framework of this research, the authors proposed an algorithm for predicting the residual life of sound-absorbing structures (SAS) from polymer composite materials (PCM) using the structural-phenomenological model. To assess the residual life of PCM structures under cyclic loading, it was proposed to use the approach of explicit description of the adhesive layer destruction process. The influence of the defect in the form of delamination on the honeycomb filler SAS operational life and stiffness was revealed. The description of the damage accumulation and destruction in the structure processes was obtained for the considered SAS under cyclic loading.
Influence of Heterogeneity Composite Filament for Additive Technology on its Electrophysical Properties at THz Range
Authors: Smygalina P P , Badin A V , Pidotova D A , Trofimov E A
Published: January 2020

In paper the results of a research of the effect of porosity on the dielectric properties of a composite filament for a 3D-printer based on the fused deposition method were presented. The process of creating a composite filaments based on acrylonitrile butadiene styrene and multi-walled carbon nanotubes is described. On a quasi-optical spectrometer, the dielectric permittivity of samples of composite materials 3D printed from a porous filament at a frequency of 210 GHz were obtained.
Quasi-Optical Resonant Single-Frequency Flaw Detector of Polymer Filament for 3D Printing
Authors: Teterina D D , Dorofeev I O , Badin A V
Published: January 2020

In the paper quasi-optical resonant single-frequency flaw detector for investigation of heterogeneity of 3D printer polymer filament are described. A scheme of quasi-optical flaw detector based on 10 GHz open resonator with a filament broaching mechanism is given. Industrial filaments based on polystyrene, polyethylene terephthalate glycol and acrylonitrile styrene acrylate were tested in a flaw detector. The measured amplitudes at the maximum of the resonance curve in the presence of a filament in the inside of the resonator are presented.
The pH Level Influence on Hydroxyapatite Phase Composition Synthesized with Hydrothermal Method
Authors: Chuprunov K , Yudin A , Lysov D , Kolesnikov E , Kuznetsov D , Leybo D , Ilinykh I , Godymchuk A
Published: January 2020

This paper reports the pH level influence on hydroxyapatite phase composition synthesized with hydrothermal method in Ca(OH)2-H3PO4, Ca(NO3)2-(NH4)2HPO4-NH4OH, Ca(OH)2-NH4H2PO4.The obtained samples were studied with X-Ray diffraction, Fourier Transform Infrared (FTIR) and Raman spectroscopy. The one phase Ca5H2O13P3 high crystallinity hydroxyapatite was synthesized with hydrothermal method at pH equal to 11. The crystallinity degree was calculated from the X-Ray diffraction pattern and became 0.96. The increasing pH level from 7 to 11 provides obtaining one phase hydroxyapatite at pH level 11 instead the two phase Ca9.04(PO4)6(OH)1.68, CaHPO4 at pH level 9 and CaPO3(OH), Ca(OH)2 at pH level 7.
Eco-friendly date-seed nanofillers for polyethylene terephthalate composite reinforcement
Authors: Elkhouly Heba I , A Rushdi Muhammad , K Abdel-Magied Ragab
Published: January 2020

Polymer composites have been widely exploited in numerous industries. Micro-particle fillers are typically added as reinforcement materials to improve the characteristics of these composites. In this work, organic nanoparticles of date seeds were added as a filler for polyethylene terephthalate (PET) to produce enhanced polymer nanocomposites. A date-seed nanofiller (DSN) was prepared and examined with x-ray diffraction measurements, and then added to PET by hot compression. The characteristics of the PET-DSN composite were experimentally investigated through tests of mass loss, compressive strength, and Vickers micro-hardness. The PET-DSN microstructure was inspected using a scanning electron microscope and Fourier-transform infrared spectroscopy. The results show chemical stability of the PET-DSN composite. Moreover, key mechanical properties of the composite, namely hardness, compressive strength and wear resistance, were improved and optimized with a DSN reinforcement of 0.75 wt%.
Preparation and high-temperature wear behavior of NiAl-Ti3AlC2 fabricated by thermal explosion
Authors: Yuan Jianjun , Wang Qingzhao , Liu Xinying , Lou Shumei , Li Qun
Published: January 2020

Abstracts

In this paper, a novel NiAl-based composite reinforced with different content Ti3AlC2 particles was fabricated by thermal explosion using Ni, Al, and Ti3AlC2 powders as starting materials. The microstructure and high-temperature wear behavior of NiAl-Ti3AlC2 composites at 600 °C were investigated. The result showed that increasing Ti3AlC2 content (lower than 15 wt%) could improve the fracture toughness of NiAl-Ti3AlC2, but for the composites with 20 wt%Ti3AlC2 content, the fracture toughness decreased due to low relative density. Wear mechanism of composites was related to the Ti3AlC2 content, the composite with a lower content exhibits oxidation wear, and higher content composite demonstrated both oxidation wear and abrasive wear.
Enhancement thermal stability and CO2 adsorption property of ZIF-8 by pre-modification with polyaniline
Authors: Wang Sheng , Cui Jiaming , Zhang Shengquan , Xie Xianfei , Xia Wenke
Published: January 2020

In this study, the thermal stability and CO2 adsorption property of ZIF-8 were effectively improved by using parallel flow-drop solvothermal method. -NH2 was successfully introduced into the surface of ZIF-8 and their structures by pre-modification with polyaniline. XRD analysis shown that the intensity of ZIF-8 characteristic peak increased with the increase doped content of polyaniline, but the crystal structure of ZIF-8 remained unchanged. FTIR analysis shown that the two new peaks at 1609 and 690 cm−1 can be attributed to the -NH2 bonding of ZIF-8. TGA analysis shown that the thermal stability of NH2-ZIF-8 was 632.71 °C. SEM analysis shown that the increase of CO2 adsorption property was due to the increase of NH2-ZIF-8 cubic crystal system. It was found that BET surface area was 789.7 m2g−1, micropore volume was 0.55 cm3g−1, pore size was 0.99 nm by taking the molar ratio of metal ions to ligands being 1:2, and the molar ratios of polyaniline to metal ions being 12%.
Autologous Costal Cartilage Harvest for Rhinoplasty with Simultaneous Breast Surgery: A Safe and Efficient Technique
Authors: Calvert Jay W , Rovelo Millicent O , Orlando Marc V , Kwon Edwin
Published: January 2020

Background

Autologous costal cartilage is frequently required for revision rhinoplasties and for challenging primary rhinoplasties. Patients undergoing a concomitant breast surgery can have costal cartilage harvested through their breast surgery incisions, thereby obviating an additional rib harvest scar. The safety and efficacy of this approach has yet to be described.

Objectives

The aim of this study was to evaluate the outcomes, safety, and results of a new technique, described here, for harvesting costal cartilage during a concomitant breast operation. Specifically, the rates of capsular contracture and rhinoplasty revisions were of great interest.

Methods

A retrospective review was performed evaluating the senior author’s experience with this technique. Data collected included patient demographics, operations performed, operative time, perioperative morbidity, and postoperative complications. Rates of capsular contracture and rhinoplasty revisions were compared with national averages.

Results

A total of 31 female patients were included. Ten (32.3%) breast complications occurred. There were 6 (19.4%) rhinoplasty complications, comprising 1 infection and 5 revisions. The capsular contracture rate was 6% and the rhinoplasty revision rate was 16%. Both of these rates are comparable to independent breast surgeries and rhinoplasties. There were no cases of perioperative mortality or major morbidity.

Conclusions

Combining breast surgery and rhinoplasty surgery allows for autologous rib harvest through the breast surgery incisions. This is a safe technique that results in outcomes similar to either procedure performed alone. In addition, the patient is spared an additional surgery and donor site scar.

Level of Evidence: 4
Responses to Wildlife Crime in Post-Colonial Times. Who Fares Best?
Authors: Sollund Ragnhild Aslaug , Runhovde Siv Rebekka
Published: January 2020

Wildlife crime is an increasing problem worldwide. Based on empirical research, we examine how the criminal justice systems of Brazil, Colombia, Uganda and Norway perceive and respond to such crime, with Norway as the main case study and basis for comparison. While the general assumption is that Northern countries are more ‘developed’ in their response to environmental problems, we argue that Norway, despite its economic resources and international profile as a supporter of environmental protection, is failing to confront illegal trade in—and protection of—endangered species nationally. We propose that these Southern countries have developed more tools in terms of legislation, enforcement, awareness and wildlife protection and that Northern countries have expectations regarding conservation in Southern countries that they themselves neglect.
The platform economy: restructuring the space of capitalist accumulation
Authors: Kenney Martin , Zysman John
Published: January 2020

The platform economy and its leading firms, such as Amazon, Facebook and Google, are reorganising the geography of value creation and capture on both a local and global scale. This article argues that economic geographers have underappreciated the implications of the platform on space. First, we demonstrate the concentration of platform giants in terms of location on the US West Coast and in terms of their market share in various services, such as search, maps and online sales. Platforms are simultaneously intermediaries, two-sided markets, data aggregators and leading users of artificial intelligence (AI). Second, we use a labour taxonomy to demonstrate the extensive reach of these platforms in terms of the labour markets that they serve and shape. To illustrate these changes in the geography of value creation, we present case studies of Amazon and Google Maps to show their effects on the location of economic activity. Third, we elaborate on our contention that platforms are at once intermediaries and data hubs. AI is likely to reinforce the power of these platform leaders because they have the largest data sets, the most computational power, enormous teams of the best AI researchers and vast reservoirs of capital that they can use to make acquisitions. We conclude by identifying areas for future research and calling upon economic geographers to consider the implications of the platform economy in reshaping the space of economic activity.
Nature of Materials in Serum That Interfere in the Glucose Oxidase—Peroxidase—o-Dianisidine Method for Glucose, and Their Mode of Action
Authors: Blaedel Walter J , Uhl James M
Published: January 2020

Separation of blood serum on Sephadex G-100 reveals three fractions that interfere with the glucose oxidase— peroxidase method for serum glucose when o-dianisidine is used as the chromogen. A low-molecular-weight fraction containing primarily uric acid, a fraction containing protein with a molecular weight of about 40 000, and a fraction of even higher molecular weight (∼ 500 000) each interfered with glucose recovery when glucose was measured by this procedure. The uric acid fraction and the isolated 40 000 molecular weight fraction interfere by competing with o-dianisidine for hydrogen peroxide in the peroxidase-catalyzed color-formation step. The high-molecular-weight fraction not only interferes with the peroxidase reaction, but also with the glucose oxidase reaction itself. These agents cause values to be low by as much as 20% in the manual determination of glucose in normal serum if their interference is not recognized.
Gas-Chromatographic Determination of Theophylline in Human Serum and Saliva
Authors: Johnson George F , Dechtiaruk Walter A , Solomon Harvey M
Published: January 2020

We report a gas-chromatographic procedure for routine determination of the bronchodilator, theophylline (1,3-dimethylxanthine), in serum and saliva. Volatile butyl derivatives for gas chromatography were prepared by the method of Greeley [Clln. Chem. 20, 192 (1974)], with butyliodide as the alkylating agent. Substances that interfere in the classical determination of theophylline, such as theobromine (3,7-dimethylxanthine) and phenobarbital, are well separated from theophylline by the gas-chromatographic procedure and can be quantitated if desired. It is possible to determine 1 µg of theophylline in 1 ml of serum or saliva. Between-run precision for 15 µg/ml samples was 5.3%. This determination is useful in assessing patient compliance with medication instructions and in adjusting dosage schedules of theophylline in patients attending a pediatric allergy clinic.
Solid-Phase Radioimmunoassay on Polystyrene Beads and Its Application to Dopamine-β-Hydroxylase
Authors: Rush Robert A , Kindler Shmuel H , Udenfriend Sidney
Published: January 2020

Antibody-coated polystyrene beads have been used to develop a solid-phase radioimmunoassay for bovine dopamine-β-hydroxylase (EC 1.14.17.1). The technique is simple and offers many advantages over other radioimmunoassay techniques, including solid-phase procedures, a major one being its adaptability to a wide range of antigen concentrations. Precision, sensitivity, and reproducibility compare favorably with those of existing methods. The ease and speed with which this test is performed have made it especially useful for clinical evaluations of serum dopamine-β-hydroxylase. Antibody-coated beads should be applicable for the assay of other antigens.
Radioimmunoassay of Digoxin—Interference by Digitoxin
Authors: Kuno-Sakai Harumi , Sakai Hideto , Ritzmann Stephan E
Published: January 2020

Digitoxin interference with radioimmunoassay of digoxin may present a problem in determining digoxin concentrations in the serum of patients treated with digitoxin less than four weeks before digoxin was administered. Digoxin and digitoxin values were determined in the sera of 54 patients who were receiving only digitoxin. Additionally, digoxin was added to aliquots of sera from a patient receiving digitoxin, and digoxin concentrations were determined by radioimmunoassay. Digitoxin interfered with radioimmunoassay of digoxin in that 9% of the digitoxin present was counted as digoxin. The resulting spuriously high value for measured digoxin in patients receiving digoxin, but treated with digitoxin previously, can be corrected by applying the following equation (units: µg/liter): Digoxin (corrected) = digoxin (measured) — [0.09 x digitoxin (measured)]. This correction, which may differ somewhat with batch of antiserum, is applicable for digitoxin concentrations up to about 50 ng/ml. Digoxin does not interfere with the digitoxin assay.
Inborn Errors of Metabolism— A Challenge to the Clinical Chemist
Authors: Eldjarn Lorentz , Jellum Egil , Stokke O
Published: January 2020

No country has as yet established satisfactory plans for combating inborn errors of metabolism. The problem is great and very complex. Some 150-200 inborn errors of metabolism are known at present, but it is likely that the types so far described only represent a fraction of those actually occurring. Until now the field of inborn errors has been dominated by pediatricians, geneticists, and biochemists. Based on his knowledge both in medicine and in biochemistry, the clinical chemist should also play an important role, and consider the diagnostic aspects of this field to be part of his responsibility. In addition, he should also take part in the further work that often is necessary to elucidate these "biochemical" disorders. The bridging of benchside and bedside medicine should be looked upon as one of the main tasks of clinical chemistry, and in the field of inborn errors such a bridging will be of great importance.
Zinc Protoporphyrin (ZPP): A Simple, Sensitive, Fluorometric Screening Test for Lead Poisioning
Authors: Lamola Angelo A , Joselow orris , Yamane T
Published: January 2020

The predominant fluorescent porphyrin that appears in erythrocytes as a result of chronic lead absorption or iron deficiency anemia is zinc protoporphyrin. This compound can be fluorometrically assayed in diluted whole blood with high sensitivity. An extremely simple and rapid test for lead absorption is described that is based on this assay. Results of a field trial indicate that this test should be seriously considered as a primary screening test for monitoring the effects of chronic lead absorption.
Organic Nitrogen-Selective Detector Used in GasChromatographic Determination of Some Anticonvulsant and Barbiturate Drugs in Plasma and Tissues
Authors: Toseland Patrick A , Albani Michael , Gauchel Franz D
Published: January 2020

The specific nitrogen flame-ionization detector was used for the rapid simultaneous determination of eight anticonvulsant drugs and one drug metabolite in plasma and for three of the drugs in tissues. The system of analysis allows the occasional rapid estimation of barbiturate in plasma. No derivative formation is required and the whole range of drugs can be determined in a single diethyl ether extract of plasma in about 20 min.
Quality Assurance in Health Care: Missions, Goals, Activities
Authors: Eilers Russell J
Published: January 2020

The most challenging mission of medical personnel today is quality assurance in health care. To meet this challenge, the essential elements of a six-phase system for total quality control for the medical laboratory are outlined under the headings of design control, incoming material control, process control, output control, reliability control, and special verification studies. Review of existing goals and activities of programs related to this mission indicates both problems and rich opportunities for individual laboratory professionals and their organizations. For effective implementation of this mission, the laboratory professionals will have to create the atmosphere of a collegium where all interested scientists communicate across disciplines to eliminate the systematic biases and improve the accuracy, precision, and specificity of clinical laboratory measuring systems, to assure medically meaningful and useful assay results for the broad spectrum of health care that is necessary for the well, the near-well, and the sick.
Kinetic Determination of Glucose with the GEMSAEC (ENI) Centrifugal Analyzer by the Glucose Dehydrogenase Reaction, and Comparison with Two Commonly Used Procedures
Authors: Lutz Rudolf A , Flückiger Jürg
Published: January 2020

A new glucose dehydrogenase preparation has been used to determine the glucose concentration in serum or plasma with the GEMSAEC(ENI) analyzer. The reaction is sufficiently linear to be suitable for a kinetic determination. A sample volume of 15 µl or less is needed, and 14 determinations can be done simultaneously within 160 s (the time needed for loading the samples and reagents into the distribution disc plus a reaction time of 70 s). The reaction is linear up to 300 mg of glucose per 100 ml, but with special computer software linearity could be extended to 1 g of glucose per 100 ml. Day-to-day and within-day precision have been tested with a number of different sera and standards. Accuracy has been checked by comparing the results with those obtained by the hexokinase and the glucose oxidase/peroxidase methods. A better agreement was found with the hexokinase method. The proposed procedure has the advantage of involving only one enzymatic step and of directly measuring reduced coenzyme formation at 340 nm.
Thyroid-Function Tests in Diphenylhydantoin-Treated Patients
Authors: Stjernholm Melvin R , Alsever Robert N , Rudolph Merritt C
Published: January 2020

We compared the free-thyroxine index in normal adults and in euthyroid patients taking diphenylhydantoin. All subjects had normal serum thyrotropin concentrations. Serum thyroxine concentrations were determined by two commonly used competitive protein-binding assays, which yielded slightly different values, but which consistently showed the same degree of decrease in mean serum thyroxine concentration in drug-treated patients as compared to the normal subjects. When 14C-labeled diphenylhydantoin was added to serum before the assay, it was separated from thyroxine in the Ames method, whereas by the Murphy-Pattee method both drug and thyroxine were extracted together. Thus, the decrease in serum thyroxine concentrations during diphenylhydantoin therapy cannot be the result of drug interference with the binding of thyroxine to binding proteins in the assays. Triiodothyronine uptake, evaluated by two methods, was identical in the two groups. The free-thyroxine indexes for all normal persons were within the manufacturer's normal range, but 21% of the drug-treated patients had subnormal indexes by the Ames method; the indexes as measured by the Murphy— Pattee method were in the lower half of the normal range. Because the triiodothyronine uptake was unaffected by the drug treatment, the decreases in the indexes must have resulted from the lower serum thyroxine concentrations. We conclude that the free-thyroxine index may not provide a valid estimate of either the clinical status or the free-thyroxine concentration in patients taking diphenylhydantoin.
Kinetic Enzymatic Method for Determining Serum Creatinine
Authors: Moss Gerald A , Bondar Richard J L , Buzzelli Diane M
Published: January 2020

Creatinine amidohydrolase is used to measure serum creatinine in a totally enzymatic procedure. Creatine, produced by hydrolysis, is acted upon by creatine kinase, and then by pyruvate kinase and lactate dehydrogenase, to result in a change in absorbance at 340 nm. The amount of creatinine present is related to the rate of change in A340 and is determined from a standard curve. Absorbance and concentration are linearly related to 100 mg/liter and only 250 µl of serum is required. At 1.0 g/liter, heparin, oxalate, citrate, ethylenediaminetetraacetate, ascorbate, or glucose had no significant effect on the accurate determination of creatinine; higher concentrations (30 g/liter) had inhibitory effects on the test. Analytical recovery of creatinine added to either normal or abnormal sera averaged 102%. When results of this procedure and of the standard direct Jaffé test were compared, the latter were significantly higher. Unlike the Jaffé method, the present method of determining creatinine is rapid (about 10 min per test), subject to few or no interfering substances, and requires no serum deproteinization.
Quantitative Method for Estimating Fecal Amino Acids
Authors: Owens Christopher W I , Padovan Walfredo
Published: January 2020

We describe a method for quantitatively estimating 24 ninhydrin-reacting substances, including the commoner amino acids, in fecal dialysate prepared from ingested dialysis bags retrieved from fresh stool. It is accurate to 2 µmol of α-amino nitrogen per liter of fecal dialysate, and for most substances recovery of added standards is 100%. It involves dilution, ultrafiltration, and automated ion-exchange column chromatography of the dialysate. Some normal values are provided.
Iodination of Morphine and Dihydromorphine, as Related to Radioimmunoassay
Authors: Davis Raymond , Feldhaus Joanne , Heveran John , Wicks Richard , Peckham Maria
Published: January 2020

Direct iodination of morphine or dihydromorphine with iodine-125 results in products that bind to antibody raised by immunization of animals with a 3-O-carboxymethylmorphine/bovine serum albumin immunogen. Iodination of morphine or dihydromorphine with iodine-127 under identical conditions failed to yield these immunologically active products, suggesting that the results obtained with iodine-125 are in part due to a radiolytic reaction not observed with the iodine-127.
Clinical Determination of Methemalbumin
Authors: Andres Scott F , Kregoski Thomas J , Frey Charles F , Joseph Ramon R , McCann Daisy S
Published: January 2020

We developed an assay for methemalbumin in biological fluids by using diethylaminoethyl-Sephadex ion-exchange chromatography to separate this protein from interfering components, including hemopexin, transferrin, hemoglobin, and haptoglobin/hemoglobin complex. Initial screening of the samples requires measurement of A280/A405 ratios of the peak tubes of the isolated albumin fraction. Values exceeding 30 indicate that methemalbumin is absent, and no further work is required. Values of less than 30 suggest that methemalbumin is present in the original sample, whereupon the presence and amount of methemalbumin can be ascertained by colorimetric assay for iron with use of ferrozine. Results may be expressed either in terms of micrograms of methemalbumin iron per gram of albumin or in milligrams of methemalbumin per liter. The reproducibility of the method is of the order of ±7% (SD). Normal persons have essentially no methemalbumin iron in their serum. Three individuals with hemorrhagic pancreatitis showed values of 65, 98, and 198 µg of methemalbumin Fe per gram of albumin.
Fluorometric Enzymatic Determination of Total Cholesterol in Serum
Authors: Huang Hua-shan , Kuan Jui-chang W , Guilbault George G
Published: January 2020

We describe a fluorometric enzymatic method for determining total serum cholesterol, based on hydrolysis of cholesterol esters to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol formed, as well as that initially present, is then oxidized by cholesterol oxidase (EC 1.1.3.6) to cholest-4-en-3-one with simultaneous production of hydrogen peroxide. The latter catalytically oxidizes homovanillic acid in the presence of peroxidase (EC 1.11.1.7) to form the highly fluorescent 2,2'-dihydroxy-3,3'-dimethoxy-biphenyl-5,5'-diacetic acid. A calibration curve is constructed from data on a series of standard cholesterol solutions vs. the corresponding fluorescence change (Δf/5 min). This curve is linear up to 4.0 g of total serum cholesterol per liter of serum. The method is specific, precise, accurate, rapid, and simple, and results correlate well with those obtained by both the Liebermann-Burchard procedure and the colorimetric enzymatic method (correlation coefficients, 0.984 and 0.981, respectively)
Improved Method for Enzymatic Determination of Serum Triglycerides
Authors: Ziegenhorn Joachim
Published: January 2020

I describe an enzymatic method for determining serum triglycerides (triacylglycerols). The triglycerides are hydrolyzed by a mixture of lipase and esterase. The glycerol released is determined by kinetic fixed-time analysis, with use of glycerol kinase, pyruvate kinase, and lactate dehydrogenase. Through addition of the competitive inhibitor ATP the Michaelis constant of pyruvate kinase is apparently increased, considerably extending the linearity of the assay. There is no need for serum blanks or reagent blanks. The method has been adapted to a centrifugal analyzer (the ENI GEMSAEC). It yields satisfactory results with regard to precision, accuracy, and insensitivity to interferences
Device for More Economical Standby Operation of Continuous-Flow Analyzers
Authors: Wardlaw Stephen C
Published: January 2020

To decrease the reagent-consumption rate of continuous-flow analyzers, I constructed a device that allows standby operation. The device, when actuated by switching off the sampler, decreases the effective pumping rate to less than 1/15 normal. The bubble pattern remains virtually undisturbed, and the system can be immediately restarted for emergency use. During five months of use in our laboratory with a Technicon platelet counter, the device has decreased reagent consumption by 60%, while allowing 24-hour-a-day operation. There have been no analytical errors traceable to the device, and no mechanical problems have arisen. I describe the use of the device in a continuous-flow system for determination of creatinine
More Sensitive Automated Detection of Polyamines in Physiological Fluids and Tissue Extracts with o-Phthalaldehyde
Authors: Marton Laurence J , Lee Patrick L Y
Published: January 2020

o-Phthalaldehyde reacts with primary amines to form an intensely blue-fluorescing product. Replacing ninhydrin with this compound in our automated high-pressure liquid-chromatographic technique for determination of polyamines, we achieved a 6-to 10-fold increase in sensitivity. Linearity and reproducibility are excellent, and the method is shown to be applicable to analysis of physiological fluids and of tissue extracts.
Continuous Determination of the Oxygen Dissociation Curve for Whole Blood
Authors: Rossi-Bernardi Luigi , Luzzana Massimo , Samaja Michele , Davi Mario , DaRiva-Ricci Daniela , Minoli Jolanda , Seaton Brian , Berger Robert L
Published: January 2020

We report here the development of a new method that allows continuous determination of the oxygen dissociation curve for microsamples (600 µl) of whole blood under conditions of pH, pco2, methemoglobin concentration, and 2,3-diphosphoglycerate content closely approaching those found in the circulatory system. The method consists of gradually oxygenating a blood sample by adding H2O2 in the presence of catalase (EC 1.11.1.6), to produce the reaction H2O2 → H2O + ½ O2. Because the total oxygen content of blood can be derived from the known rate of H2O2 addition and the po2 is determined in the liquid phase by an oxygen electrode, the two functions (total O2 content) and (% oxygen saturation) vs. po2 are simple to calculate. pco2 and pH are controlled by adding base simultaneously with the gradual oxygenation of blood. The method described thus avoids the direct measurement of oxygen saturation of whole blood.
Enhancing Effect of Surfactant and Protein on Hydrolysis of Thymolphthalein Monophosphate by Purified Prostatic Acid Phosphatase
Authors: Foti Andras G , Herschman Harvey , Cooper J Fenimore , imFeld Hedi
Published: January 2020

Purified prostatic acid phosphatase catalyzes the hydrolysis of thymolphthalein monophosphate 10-fold faster if an optimal concentration of Brij 35 (a wetting agent) or protein (bovine serum albumin or human serum proteins) is present. Results of gel filtration, dialysis, and sucrose density-gradient centrifugation analysis suggest that the substrate must combine with detergent or protein before the enzyme can catalyze its hydrolysis.
Enzymatic Immunoassay vs. Gas/Liquid Chromatography for Determination of Phenobarbital and Diphenylhydantoin in Serum
Authors: Booker Harold E , Darcey Barbara A
Published: January 2020

The antiepileptic drugs diphenylhydantoin and phenobarbital were measured in serum by a new commercially available enzyme immunoassay procedure ("EMIT," Syva Corp.). The procedure requires <5 min and no more than 50 µl of serum per determination. It is simple; only four steps (pipetting and diluting with an automatic pipettor-dilutor) are required before spectrophotometry. Twenty replicate analyses of a serum containing phenobarbital and diphenylhydantoin gave results with a CV of 6.8% and 9.1%, respectively. Results attained in a large series of patients were compared with results by a gas/liquid chromatographic procedure. For phenobarbital r = 0.97, and for diphenylhydantoin r = 0.98. No false negatives or false positives were encountered.
Screening for Albuminuria: A Case for Estimation of Albumin in Urine
Authors: BenGershôm E
Published: January 2020

The usefulness of bromcresol green for estimating albumin in urine was evaluated by comparison with the Laurell "rocket" technique. In contrast to the bromcresol green method applied for urinary albumin, rather doubtful results were obtained with conventional (Microzone) electrophoresis for albumin and with precipitation techniques for total protein estimation. Albumin estimation with bromcresol green is recommended as a more reliable substitute for total-protein estimations in urine. Limitations of bromcresol green are also pointed out.
Pollution Control and Suggested Disposal Guidelines for Clinical Chemistry Laboratories
Authors: Pragay Desider A
Published: January 2020

Pollutants generated by clinical chemistry laboratories of two cities (Buffalo, N. Y. and Rochester, N. Y.) are described. A stepwise procedure is suggested on how to deal with the toxic liquid wastes from such laboratories. A brief guideline of chemical procedures for the decontamination of selected toxic elements and compounds is included.
Diagnosis of Type III Hyperlipoproteinemia by Chromatography of Plasma Lipoproteins on Columns Containing Agarose
Authors: Shepherd James , Packard Christopher J , Dryburgh Frances J , Third Jane L H C
Published: January 2020

Agarose column chromatography has been used to separate plasma lipoproteins into very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL). Applied to the diagnosis of primary type III hyperlipoproteinemia, the procedure is capable of demonstrating three characteristic and specific changes from normality in the elution pattern of lipoproteins from patients with this condition. In the type III profile there is (a) incomplete separation of VLDL from putative LDL material, (b) early elution of the type III LDL with respect to a normal LDL marker, and (c) relative deficiency of type III LDL with elution characteristics of normal LDL. We advocate the use of this method in the diagnosis of type III hyperlipoproteinemia.
Gas-Chromatographic/Mass-Spectrometric Identification and Quantitation of Tetronic and Deoxytetronic Acids in Urine from Normal Adults and Neonates
Authors: Thompson John A , Markey Sanford P , Fennessey Paul V
Published: January 2020

Gas chromatographic/mass spectrometric/computer analyses of trimethylsilyl derivatives of urine extracts, prepared by an anion-exchange procedure, reveal the presence of several tetronic and deoxytetronic acids. Identifications were confirmed by comparing gas-chromatographic methylene unit values and mass spectrometric characteristics with those of chemically synthesized samples. In addition, several 1,4-lactones corresponding to the acids were detected in small amounts. The acids were measured in groups of adults and neonates by gas chromatographic/computer determination of peak areas and the use of calculated response factors. In urines from adults, 4-deoxythreonic, threonic, and erythronic acids were present in relatively large amounts. 4-Deoxyerythronic and 2-deoxytetronic acids were present in small to moderate amounts; 3-deoxytetronic and 2-methylglyceric acids were only trace constituents. These latter two acids, in addition to 4-deoxyerythronic, were also trace constituents of several urines from neonates but could not be detected in others. Expressed in terms of creatinine excretion, both groups excreted similar amounts of 4-deoxythreonic acid and neonates excreted significantly more 2-deoxytetronic, erythronic, and threonic acids.
Gas-Chromatographic Measurement of Codeine and Norcodeine in Human Plasma
Authors: Brunson Mary K , Nash J Frank
Published: January 2020

A gas-chromatographic method is described for determination of codeine and norcodeine in human plasma. The method is specific, sensitive, and precise. It was developed for use in bioavailability studies of therapeutic doses of codeine sulfate. After ingestion of a 60-mg codeine sulfate tablet, mean peak codeine concentration in plasma was 107 µg/liter at 1.0 hour. No measurable concentration of norcodeine was found in the plasma by this method.
Sex-Related Patterns in the Profiles of Human Urinary Amino Acids
Authors: Dirren Henri , Robinson Arthur B , Pauling Linus
Published: January 2020

The urinary amino acid profiles of 79 young women and 72 young men were studied with an automated high-pressure amino acid analyzer. A nonparametric statistical analysis was applied for detecting profile differences related to sex and other variables. A strong sex-related pattern was confirmed and its power for sex determination was evaluated. For the women, profile differences related to the use of oral contraceptives were also discovered and evaluated. No correlation with the menstrual cycle was detected.
Improved High-Resolution High-Voltage Paper Electrophoresis System for Use in Screening for Aminoacidopathies
Authors: Spiekerman A M , Hetherly Melvin E , Hall Frank F
Published: January 2020

High-voltage paper electrophoresis of small samples of serum and urine at pH 6.0 resolves basic and acidic amino acids and separates them from the neutral amino acids. For separation and identification of the neutral amino acids, the appropriate area of the electrophoretogram is cut out, sewn onto a second sheet of paper, and rerun at pH 1.9. By this method, amino acids are rapidly resolved. It is suited for use with special procedures such as oxidation of biological fluid with performic acid and specific staining for confirmation of amino acid identification.
Use of the Carbon Rod Atomizer for Analysis of Lead in Blood: Three Methods Compared
Authors: Volosin Michael T , Kubasik Norman P , Sine Harrison E
Published: January 2020

Measurement of lead in whole blood by use of the carbon rod atomizer and atomic absorption spectrophotometry was investigated for three methods: (a) a simple dilution (one volume of whole blood to two volumes of surfactant solution; (b) direct analysis of whole blood (no sample preparation); and (c) a standard chelation extraction procedure in which sodium diethyldithiocarbamate and methyl isobutyl ketone (isopropylacetone) are used. Within-run precision data for normal and abovenormal pools favored the Triton dilution method, for which coefficients of variation were less than 5%. Recoveries of added lead ranged from 94-107% for all three methods. We saw no change in the standard curves for any of the procedures on addition of ethylenediaminetetraacetate to samples. The method of additions was necessary to prepare standards of a matrix composition identical to that of the unknowns.
Improved Method for Densitometry of Electrophoretic Lipoprotein Fractions
Authors: McTaggart Wesley G , Dwyer James L
Published: January 2020

We evaluated a method for the densitometric quantitation of the electrophoretic lipoprotein fractions that sets the limit of integration at the beta-lipoprotein peak maximum. Results were compared with the more conventional method of placing the limit of integration in the valley between the beta- and pre-beta-lipoprotein peaks. The criterion of symmetrical beta-lipoprotein peaks imposed by the method was tested, and manual determination of the beta peak maximum was compared to automatic computer analysis. Computer-generated curves simulating increasing overlap of constant shape beta and pre-beta peaks were analyzed by the two methods. The conventional method introduces an error that increases with increasing overlap, but with the present method results agreed with those for completely resolved peaks. The beta peak was best approximated by an isosceles triangle (at least for the electrophoresis technique used in these studies), indicating symmetry of the beta peak. Values for the area under the lipoprotein peaks obtained by manual and computer placement of the integration limits agreed well (r = .892 to .998; SE of estimate = .0264 to .0306). The "beta peak maximum" method of densitometric quantitation avoids the problems associated with partial resolution of the beta- and pre-beta-lipoproteins. It is equally adaptable to either visual placement of the limits of integration or computer analysis.
Theory of Photometric Errors Applied to the Design and Evaluation of a High-Performance Filter Photometer
Authors: Hewitt Thomas E , Pardue Harry L
Published: January 2020

We have applied a comprehensive theory of photometric errors to the design and evaluation of an inexpensive stabilized photometer. The photometer is described in terms of a group of modules, the characteristics of which are described in terms of their effect on specific error coefficients. Procedures described in this paper show how the principles described earlier [Clin. Chem. 20, 1028 (1974)] can be used to optimize the design of new instrumentation or to evaluate the performance of existing instrumentation. Chemical data are included to verify the agreement between predicted and experimental results
Presence of Carotenoids in the Erythrocyte Membranes of Carotenemic and Noncarotenemic Individuals
Authors: Mathews-Roth Micheline M
Published: January 2020

Erythrocytes and erythrocyte membcarotenemic (serum carotene >4.0 mg/liter) and noncarotenemic individuals contain a small amount of carotenoid pigments. The principal pigment isolated from erythrocytes and erythrocyte membranes from carotenemic individuals cochromatographed with, and has an absorption spectrum similar to, authentic beta-carotene. Traces of beta-carotene were also found in the extracts of the erythrocytes and membranes obtained from the noncarotenemic individuals. These pigments were demonstrable only when the erythrocytes were extracted in the presence of an anti-oxidant (pyrogallol). Anti-oxidants should be used in the extraction and saponification process when only small samples are available or when only small amounts of carotenoid pigments are present in the material to be extracted.