scholarly journals Technical Note: Simultaneous measurement of sedimentary N<sub>2</sub> and N<sub>2</sub>O production and a modified <sup>15</sup>N isotope pairing technique

2013 ◽  
Vol 10 (12) ◽  
pp. 7847-7862 ◽  
Author(s):  
T.-C. Hsu ◽  
S.-J. Kao
Keyword(s):  
Sediment Cores ◽  
Technical Note ◽  
Ammonium Oxidation ◽  
Modified Method ◽  
Production Ratio ◽  
Incubation Experiments ◽  
Comprehensive Information ◽  
Subsequent Measurement ◽  
Isotope Pairing ◽  
Better Than

Abstract. Dinitrogen (N2) and/or nitrous oxide (N2O) are produced through denitrification, anaerobic ammonium oxidation (anammox) or nitrification in sediments, of which entangled processes complicate the absolute rate estimations of gaseous nitrogen production from individual pathways. The classical isotope pairing technique (IPT), the most common 15N nitrate enrichment method to quantify denitrification, has recently been modified by different researchers to (1) discriminate between the N2 produced by denitrification and anammox or to (2) provide a more accurate denitrification rate under considering production of both N2O and N2. In case 1, the revised IPT focused on N2 production being suitable for the environments of a low N2O-to-N2 production ratio, while in case 2, anammox was neglected. This paper develops a modified method to refine previous versions of IPT. Cryogenic traps were installed to separately preconcentrate N2 and N2O, thus allowing for subsequent measurement of the two gases generated in one sample vial. The precision is better than 2% for N2 (m/z 28, m/z 29 and m/z 30), and 1.5% for N2O (m/z 44, m/z 45 and m/z 46). Based on the six m/z peaks of the two gases, the 15N nitrate traceable processes including N2 and N2O from denitrification and N2 from anammox were estimated. Meanwhile, N2O produced by nitrification was estimated via the production rate of unlabeled 44N2O. To validate the applicability of our modified method, incubation experiments were conducted using sediment cores taken from the Danshuei Estuary in Taiwan. Rates of the aforementioned nitrogen removal processes were successfully determined. Moreover, N2O yield was as high as 66%, which would significantly bias previous IPT approaches if N2O was not considered. Our modified method not only complements previous versions of IPT but also provides more comprehensive information to advance our understanding of nitrogen dynamics of the water–sediment interface.

scholarly journals Technical Note: Simultaneous measurement of sedimentary N<sub>2</sub> and N<sub>2</sub>O production and new <sup>15</sup>N isotope pairing technique

2013 ◽  
Vol 10 (4) ◽  
pp. 6861-6898 ◽  
Author(s):  
T.-C. Hsu ◽  
S.-J. Kao
Keyword(s):  
Nitrogen Removal ◽  
Simultaneous Measurement ◽  
Sediment Cores ◽  
Technical Note ◽  
New Method ◽  
Ammonium Oxidation ◽  
N2o Production ◽  
Relative Contribution ◽  
Isotope Pairing ◽  
Removal Processes

Abstract. Dinitrogen (N2) and/or nitrous oxide (N2O) are produced through denitrification, anaerobic ammonium oxidation (anammox) or nitrification in sediments, of which entangled processes obfuscate the absolute rate estimation of gaseous nitrogen production from individual pathway. Recently, the classical isotope pairing technique (IPT), the most common 15N-nitrate enrichment method to quantify denitrification, has been modified by different researchers to (1) discriminate relative contribution of N2 production by denitrification from anammox or to (2) provide more accurate denitrification rate by considering both N2O and N2 productions. Both modified methods, however, have deficiencies such as overlooking N2O production in case 1 and neglecting anammox in case 2. In this paper, a new method was developed to refine previous methods. We installed cryogenic traps to pre-concentrate N2 and N2O separately, thus, allowing simultaneous measurement for two gases generated by one sample. The precision is better than 2% for N2 (m/z 28, m/z 29 and m/z 30), and 1.5% for N2O (m/z 44, m/z 45 and m/z 46). Based on the six m/z peaks of the two gases, we further revised IPT formulae to truthfully resolve the production rates of N2 and N2O contributed from 3 specific nitrogen removal processes, i.e. N2 and N2O from denitrification, N2 from anammox and N2O from nitrification. To validate the applicability of our new method, incubation experiments were conducted using sediment cores taken from the Danshuei estuary in Taiwan. We successfully determined the rates of aforementioned nitrogen removal processes. Moreover, N2O yield was as high as 66%, which no doubt would significantly bias previous IPT approaches when N2O was not considered. Our new method not only complements the previous IPT but also provides more comprehensive information to advance our understanding of nitrogen dynamics through the water-sediment interface.

scholarly journals Pollen analysis: state of the art

2010 ◽  
Vol 31 (1-2) ◽  
pp. 151-159 ◽  
Author(s):  
Gordon J. Ogden
Keyword(s):  
North America ◽  
Pollen Analysis ◽  
Sediment Cores ◽  
Data Bank ◽  
Sedimentation Rates ◽  
Data Set ◽  
Radiocarbon Dates ◽  
Surface Pollen ◽  
Pollen Stratigraphy ◽  
Better Than

Although nearly 50 years have passed since P.B. Sears introduced pollen analysis to North America, it remains an occult art. Dramatic improvements in sampling and analytic techniques continue to be limited by intractable problems of differential production, dispersal, ballistics, sedimentation, and preservation. It is a basic tenet of pollen stratigraphy that the data set, consisting primarily of microfossils preserved in sediments, is better than anything we have yet been able to do with it. Basic agreement between late- and postglacial pollen records has been confirmed wherever the method has been applied. Quantitative sampling techniques, sample preparation, and analytic procedures, together with multiple radiocarbon dates, permits calculation of sedimentation rates and absolute pollen influx. Of approximately 300 sediment cores from northeastern North America, fewer than 30 have more than 3 radiocarbon determinations from which least squares power curve regressions can be reliably calculated in the determination of sedimentation rates. Analogy with modern environments represented by surface pollen spectra is limited by an insufficient number of samples of uniform quality to characterize a vegetational mosaic covering 40 degrees of latitude (40-80°N) and longitude (60-100°W). The present surface pollen data bank includes about 700 samples, unevenly spaced and of uneven quality, permitting a grid resolution of no better than 10,000 km2.

Technical Note. Labral-ligamentous complex of the shoulder: Evaluation with double oblique axial MR arthrography

2003 ◽  
Vol 44 (4) ◽  
pp. 435-439
Author(s):  
T. Sasaki ◽  
Y. Saito ◽  
H. Yodono ◽  
G. L. M. Prado ◽  
H. Miura ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Mr Arthrography ◽  
Technical Note ◽  
Glenoid Fossa ◽  
Glenohumeral Ligament ◽  
Inferior Glenohumeral Ligament ◽  
Scout Image ◽  
Weighted Sequences ◽  
Better Than

Purpose: To assess the ability of double oblique axial (DOA) MR arthrography in evaluating labral-ligamentous complex compared with conventional axial (CA) MR arthrography. Material and Methods: MR arthrography of 51 shoulders, subsequently examined with arthroscopy, were retrospectively reviewed. DOA imaging was performed in all 51 shoulders and both DOA and CA imaging in 37 using a 1.5 T unit with gradient recalled-echo T2*-weighted sequences. DOA imaging was performed using perpendicular planes to the long axis of the glenoid fossa obtained by an oblique sagittal scout image. We compared the ability of DOA with that of CA MR arthrography to assess labral injuries and to demonstrate the whole length of the anterior band of the inferior glenohumeral ligament (AIGHL), which were shown to be intact by arthroscopy. Results: For anterior labral injuries, sensitivity and specificity were 87% and 93% with CA, and 94% and 100% with DOA imaging, respectively. For posterior labral injuries, sensitivity and specificity were 47% and 100% with CA, and 79% and 96% with DOA imaging, respectively. There were no statistically significant differences between CA and DOA images, except for the ability to diagnose posterior labral injuries, where DOA imaging had a significant superior sensitivity ( p = 0.0327). DOA images also demonstrated the whole length of the intact AIGHL in 10 of 11 shoulders, while CA imaging showed this in only 3 of 11. Conclusion: DOA imaging was equal or better than CA imaging for evaluating the labral-ligamentous complex.

scholarly journals A New Generalized t Distribution Based on a Distribution Construction Method

Mathematics ◽  
2021 ◽  
Vol 9 (19) ◽  
pp. 2413
Author(s):  
Ruijie Guan ◽  
Xu Zhao ◽  
Weihu Cheng ◽  
Yaohua Rong
Keyword(s):  
Maximum Likelihood ◽  
Em Algorithm ◽  
Iterative Algorithm ◽  
Likelihood Estimation ◽  
Estimation Methods ◽  
Modified Method ◽  
The Em Algorithm ◽  
Likelihood Approach ◽  
T Distribution ◽  
Better Than

In this paper, a new generalized t (new Gt) distribution based on a distribution construction approach is proposed and proved to be suitable for fitting both the data with high kurtosis and heavy tail. The main innovation of this article consists of four parts. First of all, the main characteristics and properties of this new distribution are outined. Secondly, we derive the explicit expression for the moments of order statistics as well as its corresponding variance–covariance matrix. Thirdly, we focus on the parameter estimation of this new Gt distribution and introduce several estimation methods, such as a modified method of moments (MMOM), a maximum likelihood estimation (MLE) using the EM algorithm, a novel iterative algorithm to acquire MLE, and improved probability weighted moments (IPWM). Through simulation studies, it can be concluded that the IPWM estimation performs better than the MLE using the EM algorithm and the MMOM in general. The newly-proposed iterative algorithm has better performance than the EM algorithm when the sample kurtosis is greater than 2.7. For four parameters of the new Gt distribution, a profile maximum likelihood approach using the EM algorithm is developed to deal with the estimation problem and obtain acceptable.

scholarly journals Portable Food Balls Extrusion Machine

2020 ◽  
Vol 9 (4) ◽  
pp. 465-468
Keyword(s):  
Technology Transfer ◽  
Research And Development ◽  
Cost Efficiency ◽  
Significant Variation ◽  
Small Scale ◽  
Business Incubation ◽  
Manual Method ◽  
Production Ratio ◽  
Commercial Value ◽  
Better Than

This study developed a portable extrusion machine for food balls products. The study used the Research and Development (R&D) process for it involved the preparation and construction of a finished product that can be used in the field of education. The extrusion machine’s cost efficiency was 10 times better than the manual method but twice lower compared to the commercial machine. There was significant variation in the weights of the food balls produced by the three methods, and the instructional and commercial value of the machine obtained an overall mean rating of 4.46 or very satisfactory. Thus, it is technically feasible to construct the portable extrusion machine in view of the expected functionality of the designed parts, the availability of supplies and materials and affordability of its cost. The construction of the machine requires procedure to follow for ease and accuracy. The portable extrusion machine is superior over the manual method but inferior to commercial units as to production ratio. Furthermore, it is more economically viable to use the portable extrusion machine for small-scale food balls production than the manual method. Potential for technology transfer/ generation and business incubation should be conducted before its release in the Philippine market

scholarly journals Technical note: A modified method to quantify prolamin proteins in dry and high-moisture corn

2013 ◽  
Vol 96 (7) ◽  
pp. 4647-4652 ◽  
Author(s):  
S.E. Nellis ◽  
P.C. Hoffman ◽  
R.D. Shaver
Keyword(s):  
Technical Note ◽  
High Moisture ◽  
Modified Method ◽  
High Moisture Corn

scholarly journals Comparative Performance Effectiveness of the Portable Food Balls Extrusion Machine

2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Ana Maria A. Bonito
Keyword(s):  
Research And Development ◽  
Cost Efficiency ◽  
Small Scale ◽  
Food Science ◽  
Comparative Performance ◽  
Performance Effectiveness ◽  
Manual Method ◽  
Production Ratio ◽  
Science Technology ◽  
Better Than

This study developed a portable extrusion machine for food balls products.The study used the Research and Development (R&D) process for it involved thepreparation and construction of a finished product that can be used in the field of education. The extrusion machine’s cost efficiency was 10 times better than the manual method but twice lower compared to the commercial machine. There wassignificant variation in the weights of the food balls produced by the three methods,and the instructional and commercial value of the machine obtained an overall meanrating of 4.46 or very satisfactory. Thus, it is technically feasible to construct theportable extrusion machine in view of the expected functionality of the designedparts, the availability of supplies and materials and affordability of its cost. Theconstruction of the machine requires procedure to follow for ease and accuracy.The portable extrusion machine is superior over the manual method but inferiorto commercial units as to production ratio. Furthermore, it is more economically viable to use the portable extrusion machine for small-scale food balls production than the manual method. Potential for technology transfer/ generation and businessincubation should be conducted before its release in the Philippine market.Keywords: Food Science Technology, portable extrusion machine, research and development, Philippines

Influence of Turbulence Modelling on Predicting the Round Jet Flow Field: Technical Note

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
D. Hasen ◽  
S. Elangovan ◽  
M. Sundararaj ◽  
K.M. Parammasivam
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Flow Regime ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Technical Note ◽  
The Other ◽  
Round Jets ◽  
Mesh Density ◽  
Better Than

In this study, the effects of different turbulence models on the decay characteristics of round jets were studied. The turbulence models considered for the current study is SST, k-ε, k-ω, RNG kε. For the entire turbulence model mesh density and boundary conditions were mentioned same. By comparing the simulated results with the experiments interesting results were obtained. SST predicts the flow better than the other models in this flow regime.

Evaluation of Cultural Methods to Isolate Salmonella from Pressed Yeast and Dried Inactive Yeast

1975 ◽  
Vol 38 (7) ◽  
pp. 383-385 ◽  
Author(s):  
CLYDE R. WILSON ◽  
WALLACE H. ANDREWS ◽  
PAUL L. POELMA
Keyword(s):  
Most Probable Number ◽  
Distilled Water ◽  
Lauryl Sulfate ◽  
Improved Method ◽  
Probable Number ◽  
Examination Procedure ◽  
Cultural Methods ◽  
Modified Method ◽  
Current Procedure ◽  
Better Than

An improved method recently developed to isolate Salmonella from dried active yeast was evaluated for use with pressed yeast and dried inactive yeast. The method for dried active yeast consists of pre-enriching a 25-g sample in trypticase soy (TS) broth at a sample-broth ratio of 1:10, incubating at 35 ± 0.5 C for 24 ± 2 h, and transferring to lauryl sulfate tryptose (LST) and tetrathionate (TT) broths. After 24 ± 2 h at 35 C, the broths are streaked to selective agars. When evaluated for use with pressed yeast, Salmonella attained higher most probable number levels/ml with this method (7.9 × 104 – 3.3 × 106), than with 1% tryptone broth and a sample-broth ratio of 1:5 (1.7 × 103 – 1.7 × 106), which is the current examination procedure for pressed yeast. Salmonella was consistently isolated from selective agars streaked from TT broth, but was seldom isolated from selective agars streaked from LST broth because of massive overgrowth by non-salmonellae. With dried inactive yeast, this modified method was equal to, but not significantly better than, pre-enrichment of the yeast in sterile distilled water at a sample-broth ratio of 1:5, which is the current procedure for dried inactive yeast.

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