scholarly journals Studies on the Preparation of Small 14C Samples with an RGA and 13C-Enriched Material

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1394-1404 ◽  
Author(s):  
Jakob Liebl ◽  
Roswitha Avalos Ortiz ◽  
Robin Golser ◽  
Florian Handle ◽  
Walter Kutschera ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Test Sample ◽  
Minimum Size ◽  
Test Material ◽  
Reaction Yield ◽  
Side Reactions ◽  
Contamination Level ◽  
Residual Gas ◽  
Contamination Levels ◽  
Physical And Chemical

The minimum size of radiocarbon samples for which reliable results can be obtained in an accelerator mass spectrometry (AMS) measurement is in many cases limited by carbon contamination introduced during sample preparation (i.e. all physical and chemical steps to which samples were subjected, starting from sampling). Efforts to reduce the sample size limit down to a few μg carbon require comprehensive systematic investigations to assess the amount of contamination and the process yields. We are introducing additional methods to speed up this process and to obtain more reliable results. A residual gas analyzer (RGA) is used to study combustion and graphitization reactions. We could optimize the reaction process at small CO2 pressures and identify detrimental side reactions. Knowing the composition of the residual gas in a graphitization process allows a reliable judgment on the completeness of the reaction. Further, we use isotopically enriched 13C (≥98% 13C) as a test material to determine contamination levels. This offers significant advantages: 1) The measurement of 12C/13C in CO2 is possible on-line with the RGA, which significantly reduces turnaround times compared to AMS measurements; 2) Both the reaction yield and the amount of contamination can be determined from a single test sample.The first applications of isotopically enriched 13C and the RGA have revealed that our prototype setup has room for improvements via better hardware; however, significant improvements of our sample processing procedures were achieved, eventually arriving at an overall contamination level of 0.12 to 0.15 μg C during sample preparation (i.e. freeze-drying, combustion, and graphitization) of μg-sized samples in aqueous solution, with above 50% yield.

Studies and Application of Auger Monitoring System for Quality Control and Assurance of Al Bondpads

2016 ◽  
Author(s):  
Hua Younan
Keyword(s):  
Quality Control ◽  
Sample Preparation ◽  
Monitoring System ◽  
Failure Mechanisms ◽  
Wafer Fabrication ◽  
Contamination Level ◽  
Auger Analysis ◽  
Low Level ◽  
Monitoring Frequency ◽  
Control Procedures

Abstract In wafer fabrication (Fab), Fluorine (F) based gases are used for Al bondpad opening process. Thus, even on a regular Al bondpad, there exists a low level of F contamination. However, the F level has to be controlled at a lower level. If the F level is higher than the control/spec limits, it could cause F-induced corrosion and Al-F defects, resulting in pad discoloration and NSOP problems. In our previous studies [1-5], the theories, characteristics, chemical and physical failure mechanisms and the root causes of the F-induced corrosion and Al-F defects on Al bondpads have been studied. In this paper, we further study F-induced corrosion and propose to establish an Auger monitoring system so as to monitor the F contamination level on Al bondpads in wafer fabrication. Auger monitoring frequency, sample preparation, wafer life, Auger analysis points, control/spec limits and OOC/OOS quality control procedures are also discussed.

scholarly journals Clostridia in Insect Processed Animal Proteins—Is an Epidemiological Problem Possible?

Agriculture ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 270
Author(s):  
Tomasz Grenda ◽  
Krzysztof Kwiatek ◽  
Magdalena Goldsztejn ◽  
Magdalena Sapała ◽  
Nina Kozieł ◽  
...  
Keyword(s):  
16S Rdna ◽  
Animal Feed ◽  
Statistical Significance ◽  
Contamination Level ◽  
Type D ◽  
Botulinum Type ◽  
Livestock Animal ◽  
Contamination Levels ◽  
Rdna Analysis ◽  
Clostridium Spp

The aim of this study was the evaluation of the insect processed animal protein (IPAP) contamination level by Clostridium spp. Particularly, we screened for the occurrence of pathogenic species of Clostridia. The samples of IPAP were derived from yellow mealworm (Tenebrio molitor) and black soldier fly (Hermetia illucens) available in the Polish market. The IPAPs were added to experimental feeds for poultry. The differences between the contamination levels of the control (without the addition of IPAP) and experimental (with the addition of IPAP) groups were monitored. The samples were also examined by culture and PCR-based methods to detect 16S rDNA and genes determining botulinum toxin (BoNT) production. Statistical significance was noticed among the feed with the IPAP addition, as well as an increase of contamination by Clostridium spp. In one sample of IPAP, the occurrence of ntnh and bont/D genes determining the production of BoNT/D was noticed. However, a positive result was noticed only at the step of the liquid culture; the Clostridium botulinum type D strain was not isolated. Phenotypically, and according to the 16S rDNA analysis, genetically similar strains to C. botulinum species were isolated. Considering the microbiological safety of IPAP and expanding possibility of its use in livestock animal feed, it seems to be reasonable to provide complex risk assessment on the potential transfer of Clostridia into feed compounds, to assure the safety and sustainable development of insect PAP industry.

The Use of Metallography for Examination of Causes of Surface Defects on Visual Parts

2017 ◽  
Vol 270 ◽  
pp. 107-111
Author(s):  
Zuzana Andršová ◽  
Pavel Kejzlar
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Surface Defects ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Visual Appearance ◽  
Visual Defects ◽  
Physical And Chemical ◽  
Microscopic Techniques ◽  
And Chemical Properties

Many of currently manufactured components intended for automotive, must not only meet the requirements on functionality, but also considerable demands on the visual appearance. Parts are subjected to thorough inspection and suppliers are forced to deal with causes of a very slight visual defects. When examining the defects, it is necessary to use a whole range of advanced analytical methods and procedures previously used only for identification of the physical and chemical properties and structure of the material. This paper deals with several examples which have been solved. It focuses especially on the use of demanding metallographic sample preparation from components with surface defects, examining the defects on the cross-section using mainly microscopic techniques and determining the causes of their generation. These results then serve as a basis for modification of the technology and thus they are the tool for significant reduction of amount of NOK parts.

scholarly journals Mycotoxins in Tea: Occurrence, Methods of Determination and Risk Evaluation

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 444 ◽  
Author(s):  
Irina Sedova ◽  
Mariya Kiseleva ◽  
Victor Tutelyan
Keyword(s):  
Ochratoxin A ◽  
Aflatoxin B1 ◽  
Health Hazard ◽  
Black Tea ◽  
Contamination Level ◽  
Protection Measures ◽  
Commodity Production ◽  
Exposure Estimate ◽  
Contamination Levels ◽  
Public Health Protection

Tea is one of the most popular beverages all over the world. Being an everyday drink for almost everyone, for centuries tea was considered safe and healthy. However, fungal contamination of tea at any stage of commodity production can pose a serious health hazard due to the accumulation of toxic secondary metabolites of moulds. Contemporary research revealed incidences of highly contaminated samples. Mycotoxin transfer from naturally contaminated raw tea into beverage was well studied for ochratoxin A only, and the possible leak of other mycotoxins is discussed. The results of several surveys were combined to evaluate aflatoxin B1 and ochratoxin A contamination levels in black tea and Pu-erh. Exposure estimate to aflatoxin B1 and ochratoxin A due to tea consumption was carried out based on these data. Average contamination level corresponds to the exposure of 3–40% (aflatoxin B1) and 5–24% (ochratoxin A) of mean overall estimates for different cluster diets. Lack of data does not allow the conclusion for the necessity of public health protection measures. It is necessary to perform representative studies of different kinds of tea for regulated mycotoxins at least. Contemporary techniques for analysis of mycotoxins in tea are summarised in the present review.

Human Urine as Test Material in1H NMR-Based Metabonomics:  Recommendations for Sample Preparation and Storage

2007 ◽  
Vol 79 (3) ◽  
pp. 1181-1186 ◽  
Author(s):  
Michael Lauridsen ◽  
Steen H. Hansen ◽  
Jerzy W. Jaroszewski ◽  
Claus Cornett
Keyword(s):  
Sample Preparation ◽  
Human Urine ◽  
Test Material ◽  
And Storage

scholarly journals Incidence and contamination level of Clostridium perfringens in meat and meat products sold in Sakarya province of Turkey

2021 ◽  
Vol 7 (3) ◽  
pp. 172-178
Author(s):  
Serap Coşansu ◽  
Şeyma Şeniz Ersöz
Keyword(s):  
Clostridium Perfringens ◽  
Meat Product ◽  
Meat Products ◽  
Ground Beef ◽  
Chicken Meat ◽  
Contamination Level ◽  
Biochemical Tests ◽  
Contamination Levels ◽  
Emulsified Meat ◽  
Cooked Meat

Totally 101 meat and meat product samples obtained from local markets and restaurants were analyzed for incidence and contamination level of Clostridium perfringens. The typical colonies grown anaerobically on Tryptose Sulfite Cycloserine Agar supplemented with 4-Methyliumbelliferyl (MUP) were confirmed by biochemical tests. Forty-eight of the samples (47.5%) were contaminated with C. perfringens. The highest incidence of the pathogen was determined in uncooked meatball samples (72.2%) followed by ground beef samples (61.3%). The incidence of C. perfringens in chicken meat, cooked meat döner, cooked chicken döner and emulsified meat product samples were 33.3, 33.3, 28.6 and 16.7%, respectively. Thirteen out of 101 samples (12.9%) yielded typical colonies on TSC-MUP Agar, but could not be confirmed as C. perfringens. Average contamination levels in sample groups ranged from 8.3 to 1.5×102 cfu/g, with the highest ground beef and the lowest chicken meat.

Assessing the wear characteristics of aggregate exposed at the road surface

1998 ◽  
Vol 13 (1) ◽  
pp. 149-157
Author(s):  
A. R. Woodside ◽  
W. D. H. Woodward
Keyword(s):  
Sample Preparation ◽  
Historical Development ◽  
Test Sample ◽  
Test Methods ◽  
Road Surface ◽  
Wear Characteristics ◽  
Density Correction ◽  
The Road ◽  
Rock Types

AbstractThis paper considers the assessment of highway surfacing aggregate wear using the Aggregate Abrasion Value and micro-Deval test methods. Their historical development is discussed. The influence of test sample preparation and number of chippings assessed is compared. Data for both methods are presented for a range of rock types. Dry, wet and soaked versions of the micro-Deval test are compared. The use of a density correction to modify the micro-Deval test value is proposed. The ability of the Aggregate Abrasion Value and micro-Deval test methods to assess heterogeneous aggregates is assessed.

Free-range eggs from a very polluted site in central Italy: levels of Polychlorinated Dibenzo-p-Dioxins/Furans and Polychlorinated Biphenyls and estimated human dietary exposure

2021 ◽  
Author(s):  
Federica Castellani ◽  
Lamberto Manzoli ◽  
Cecilia Acuti Martellucci ◽  
Maria Elena Flacco ◽  
Maria Luisa Astolfi ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Central Italy ◽  
Dietary Exposure ◽  
Contamination Level ◽  
Free Range ◽  
Weekly Intake ◽  
Tolerable Weekly Intake ◽  
Commission Regulation ◽  
Contamination Levels ◽  
A Site

The aim of the present study was to evaluate the contamination levels of some classes of persistent organic pollutants (POPs) in free-range hen eggs and to estimate the related human dietary exposure in a Site of National Interest (SNI), characterized by a serious state of environmental pollution (Bussi sul Tirino area, central Italy). For these purposes, 17 samples of free-range hen eggs collected in home-producing farms located in the SNI territory were analyzed for 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 12 dioxin-like polychlorinated biphenyls (dl-PCBs) and 6 non-dioxin-like PCBs (ndl-PCBs). Dietary exposure was assessed assuming a standard consumption of eggs per week. The concentration of ∑PCDD/Fs + dl-PCBs ranged from 0.463 to 8.028 pg TEQ (Toxic Equivalent) g−1 fat, while the mean contamination level of the ∑ndl-PCBs ranged from 0.234 to 7.741 ng TEQ g−1 fat. PCDD/Fs and PCBs contamination levels were lower than maximum values established by the Commission Regulation (EU) 1259/2011, except for one sample. The estimated weekly intake (EWI), calculated in order to evaluate the contribution in terms of the monitored pollutants of the locally produced eggs to the diet, was lower than the tolerable weekly intake (TWI) established by the European Food Safety Authority (EFSA).

scholarly journals Simultaneous Determination of Twenty Mycotoxins in the Korean Soybean Paste Doenjang by LC-MS/MS with Immunoaffinity Cleanup

Toxins ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 594 ◽  
Author(s):  
So Young Woo ◽  
So Young Ryu ◽  
Fei Tian ◽  
Sang Yoo Lee ◽  
Su Been Park ◽  
...  
Keyword(s):  
Measurement Uncertainty ◽  
Simultaneous Determination ◽  
Ochratoxin A ◽  
Matrix Effect ◽  
Contamination Level ◽  
Immunoaffinity Column ◽  
Good Linearity ◽  
Soybean Paste ◽  
Contamination Levels

Doenjang, a Korean fermented soybean paste, is vulnerable to contamination by mycotoxins because it is directly exposed to environmental microbiota during fermentation. A method that simultaneously determines 20 mycotoxins in doenjang, including aflatoxins (AFs), ochratoxin A (OTA), zearalenone (ZEN), and fumonisins (FBs) with an immunoaffinity column cleanup was optimized and validated in doenjang using LC-MS/MS. The method showed good performance in the analysis of 20 mycotoxins in doenjang with good linearity (R2 > 0.999), intra- and inter-day precision (<16%), recovery (72–112%), matrix effect (87–104%), and measurement uncertainty (<42%). The validated method was applied to investigate mycotoxin contamination levels in commercial and homemade doenjang. The mycotoxins that frequently contaminated doenjang were AFs, OTA, ZEN, and FBs and the average contamination level and number of co-occurring mycotoxins in homemade doenjang were higher than those in commercially produced doenjang.

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