scholarly journals PADC-NTM Applied in 7Li+Pb at 31 MeV Reaction Products Study

Author(s):  
M. Cinausero ◽  
A. M. Sajo-Castelli ◽  
L. Sajo-Bohus ◽  
J. Palfalvi ◽  
G. Espinosa

Passive nuclear track methodology (NTM) is applied to study charged particles products of the reaction 7Li+Pb at ~ 31 MeV. It is a contribution to the 8pLP Project (LNL-INFN-Italy) in where we show an alternative approach to register charged particle from reaction fragments by PADC detection. The main advantage is that the passive system integrates data over the whole experiment and has its importance for low rate reaction processes. Reaction products as well as scattered beam particles are determined from track shape analysis. Some limitations are inherent to NTM since a priori knowledge is required to correlate track size distribution given by each type of particle emerging from the target. Results show that the passive technique gives useful information when applied in reaction data interpretation for a relatively large range of particle types.

The gas-phase thermal oxidation of butene-2 has been examined over the temperature range 289 to 395°C. No difference in behaviour of the cis and trans forms could be detected. At the higher temperatures the reaction resembled that of the oxidation of propylene in the shape of the pressure-time curve and in the identity of many of the reaction products. At the lower temperatures a decrease in pressure partly due to peroxide formation followed the induction period, and by the end of this time much of the initial oxygen had been consumed. At all temperatures excess olefin produced an apparent inhibiting effect manifested by a decreased yield of carbon monoxide and a fall-off in the maximum rate of pressure change and total pressure change. Reaction processes are discussed, and it is suggested that a peroxide precedes the formation of acetaldehyde. Branching occurs largely through reaction of acetyl radicals produced from the acetaldehyde. The inhibiting effects produced by excess olefin are attributed to the replacement of reactive radicals by the less reactive allylic-type radicals, and the addition reactions of olefin at higher olefin concentrations lead to polymerization and a low or negative overall pressure change.


RSC Advances ◽  
2018 ◽  
Vol 8 (6) ◽  
pp. 3286-3295 ◽  
Author(s):  
A. S. Portnyagin ◽  
A. P. Golikov ◽  
V. A. Drozd ◽  
V. A. Avramenko

Presented method of kinetic analysis of non-isothermal reaction data provides precise kinetic parameters for different materials with different morphology and particle size.


GigaScience ◽  
2020 ◽  
Vol 9 (10) ◽  
Author(s):  
Katrina L Kalantar ◽  
Tiago Carvalho ◽  
Charles F A de Bourcy ◽  
Boris Dimitrov ◽  
Greg Dingle ◽  
...  

Abstract Background Metagenomic next-generation sequencing (mNGS) has enabled the rapid, unbiased detection and identification of microbes without pathogen-specific reagents, culturing, or a priori knowledge of the microbial landscape. mNGS data analysis requires a series of computationally intensive processing steps to accurately determine the microbial composition of a sample. Existing mNGS data analysis tools typically require bioinformatics expertise and access to local server-class hardware resources. For many research laboratories, this presents an obstacle, especially in resource-limited environments. Findings We present IDseq, an open source cloud-based metagenomics pipeline and service for global pathogen detection and monitoring (https://idseq.net). The IDseq Portal accepts raw mNGS data, performs host and quality filtration steps, then executes an assembly-based alignment pipeline, which results in the assignment of reads and contigs to taxonomic categories. The taxonomic relative abundances are reported and visualized in an easy-to-use web application to facilitate data interpretation and hypothesis generation. Furthermore, IDseq supports environmental background model generation and automatic internal spike-in control recognition, providing statistics that are critical for data interpretation. IDseq was designed with the specific intent of detecting novel pathogens. Here, we benchmark novel virus detection capability using both synthetically evolved viral sequences and real-world samples, including IDseq analysis of a nasopharyngeal swab sample acquired and processed locally in Cambodia from a tourist from Wuhan, China, infected with the recently emergent SARS-CoV-2. Conclusion The IDseq Portal reduces the barrier to entry for mNGS data analysis and enables bench scientists, clinicians, and bioinformaticians to gain insight from mNGS datasets for both known and novel pathogens.


2017 ◽  
Vol 10 (1) ◽  
pp. 119-153 ◽  
Author(s):  
Nicolas Theys ◽  
Isabelle De Smedt ◽  
Huan Yu ◽  
Thomas Danckaert ◽  
Jeroen van Gent ◽  
...  

Abstract. The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Copernicus Sentinel-5 Precursor (S-5P) platform will measure ultraviolet earthshine radiances at high spectral and improved spatial resolution (pixel size of 7 km  ×  3.5 km at nadir) compared to its predecessors OMI and GOME-2. This paper presents the sulfur dioxide (SO2) vertical column retrieval algorithm implemented in the S-5P operational processor UPAS (Universal Processor for UV/VIS Atmospheric Spectrometers) and comprehensively describes its various retrieval steps. The spectral fitting is performed using the differential optical absorption spectroscopy (DOAS) method including multiple fitting windows to cope with the large range of atmospheric SO2 columns encountered. It is followed by a slant column background correction scheme to reduce possible biases or across-track-dependent artifacts in the data. The SO2 vertical columns are obtained by applying air mass factors (AMFs) calculated for a set of representative a priori profiles and accounting for various parameters influencing the retrieval sensitivity to SO2. Finally, the algorithm includes an error analysis module which is fully described here. We also discuss verification results (as part of the algorithm development) and future validation needs of the TROPOMI SO2 algorithm.


2020 ◽  
Vol 40 (6) ◽  
pp. 451-457 ◽  
Author(s):  
Guanghui Zhu ◽  
Chiho Kim ◽  
Anand Chandrasekarn ◽  
Joshua D. Everett ◽  
Rampi Ramprasad ◽  
...  

AbstractPredicting gas permeabilities of polymers a priori is a long-standing challenge within the membrane research community that has important applications for membrane process design and ultimately widespread adoption of membrane technology. From early attempts based on free volume and cohesive energy to more recent group contribution methods, the ability to predict membrane permeability has improved in terms of accuracy. However, these models usually stay “within the paper”, i.e. limited model details are provided to the wider community such that adoption of these predictive platforms is limited. In this work, we combined an advanced polymer chemical structure fingerprinting method with a large experimental database of gas permeabilities to provide unprecedented prediction precision over a large range of polymer classes. No prior knowledge of the polymer is needed for the prediction other than the repeating unit chemical formula. In addition, we have incorporated this model into the existing Polymer Genome project to make it open to the membrane research community.


Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 446
Author(s):  
Yair Lakretz ◽  
Stanislas Dehaene ◽  
Jean-Rémi King

Sentence comprehension requires inferring, from a sequence of words, the structure of syntactic relationships that bind these words into a semantic representation. Our limited ability to build some specific syntactic structures, such as nested center-embedded clauses (e.g., “The dog that the cat that the mouse bit chased ran away”), suggests a striking capacity limitation of sentence processing, and thus offers a window to understand how the human brain processes sentences. Here, we review the main hypotheses proposed in psycholinguistics to explain such capacity limitation. We then introduce an alternative approach, derived from our recent work on artificial neural networks optimized for language modeling, and predict that capacity limitation derives from the emergence of sparse and feature-specific syntactic units. Unlike psycholinguistic theories, our neural network-based framework provides precise capacity-limit predictions without making any a priori assumptions about the form of the grammar or parser. Finally, we discuss how our framework may clarify the mechanistic underpinning of language processing and its limitations in the human brain.


2016 ◽  
Vol 47 (1) ◽  
pp. 130-147 ◽  
Author(s):  
Margaret Stout ◽  
Jeannine M. Love

Public encounters, the micro-level relational process of face-to-face contact between public professionals and community members, are argued to have a meaningful effect on the outcomes of governance activities. In turn, the specific characteristics of these encounters are constrained by institutionalized macro-level structures, yet the variety of contexts and associated relational styles have not been carefully explored. Therefore, in this article, public encounters are considered in light of a particular governance typology to (a) clearly differentiate macro-level contexts, (b) clearly differentiate the associated styles of relating in each type of public encounter, (c) describe the ways in which these interactions hinder or foster productive processes and outcomes, and (d) identify a preferred approach for potentially more fruitful results. In this way, the article provides a theoretical platform for future analysis of empirical cases. This theoretical analysis reveals the pathological dynamics in public encounters produced by typical approaches to governance and offers an alternative approach that may produce more effective public encounters. Specifically, using the method of integration described by Progressive Era scholar Mary Follett, we argue fruitful public encounters entail a relational disposition, a cooperative style of relating, a collaborative mode of association, and a method for achieving integration that enables constructive conflict through disintegration of a priori positions; collaborative discovery of facts and values; revaluation of desires and methods through dialogue; creative and integrative determinations; collective responsibility; and experientially founded commitment.


Author(s):  
P. F. Flynn ◽  
H. G. Weber

A fundamental theoretical study of the flow within a compressor wheel suggests that: (a) a necessary (but not sufficient) criterion for the prevention of surge can be obtained from the inviscid solution of the internal compressor flow problem, (b) the use of backward leaning blades is not the only blade passage modification which has the potential to increase the usable flow range of the compressor, and (c) a usable flow range much broader than previously thought to exist can be obtained. One alternative approach suggested by this study has been experimentally tested up to compressor pressure ratios in excess of 3.0. The new approach allowed a 50 percent reduction in the surge mass flow at design impeller speed while maintaining the inducer geometry of the machine identical to that of a conventional radial-bladed impeller used as a comparison standard. This new approach indicates the potential for a-priori prediction of surge flow characteristics of radial turbomachinery. Conversely, the design of hardware to a prespecified surge to choke flow ratio may be able to be accomplished by predefined blade geometry. It appears that the usable flow range for centrifugal compressors could extend down to 15 to 20 percent of the choke flow capability without sacrificing maximum component efficiencies.


Author(s):  
Л.Ф. Нурисламова ◽  
И.М. Губайдуллин

Авторами статьи ведутся работы, направленные на разработку численного подхода к анализу параметрической идентифицируемости модели химической реакции методами анализа чувствительности для эффективного исследования и управления процессом химической реакции. Целью настоящей работы является определение параметров, подлежащих идентификации в условиях задаваемой погрешности измерений, химической реакции на примере процесса пиролиза пропана и определение незначимых параметров модели. Выполнена редукция 157-стадийной детальной схемы пиролиза пропана к 30-стадийной схеме. Предложена кинетическая модель для анализа низкотемпературного пиролиза пропана. Модель адекватно описывает выход наблюдаемых продуктов реакции при атмосферном давлении. Идентифицированы параметры кинетической модели пиролиза пропана путем решения обратной задачи химической кинетики. The authors of this paper develop a numerical approach to analyze the parametric identifiability of chemical reaction models by the methods of sensitivity analysis for the efficient study and management of chemical reaction processes. The primary objective of this paper is to determine the parameters to be identified for the propylene pyrolysis process and to determine the insignificant parameters of the model. The 157-step detailed pyrolysis scheme of propane is reduced to the 30-step scheme. A kinetic model is proposed to analyze the low-temperature pyrolysis of propane. This model adequately describes the yield of observed reaction products at atmospheric pressure. The parameters of the kinetic model of propane pyrolysis are identified by solving the inverse problem of chemical kinetics.


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