bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identificación de cadáveres sometidos a altas temperaturas, a partir de las características macroscópicas de sus órganos dentales y la aplicabilidad de la genética forense / Identification of Bodies Exposed to High Temperatures Based on Macroscopic...
Authors: Barraza Salcedo María Del Socorro , Rebolledo Cobos Martha Leonor 
Published: December 2016

<p><strong>ABSTRACT. </strong><em><strong>Background:</strong></em> Forensic dentistry in cases of incineration provides scientific elements that allow the identification of bodies, by analyzing dental organs, through the isolation of DNA obtained from the pulp as an alternative to confirm the identity of the victim. When the degree of temperature is highly elevated, dental tissues are vulnerable and therefore the DNA pulp is not salvageable, wasting resources and time by lack of standards to identify macroscopic characteristics that indicate this situation reliably. <em><strong>Objective:</strong></em> To describe the main features of teeth subjected to high temperatures and the relationship of these to the viability of their DNA, as a contribution to forensic genetic identification. <em><strong>Methods:</strong></em> A literature search for three databases were used; Pubmed, EBSCO and Google academician, 50 articles were selected in several languages, which made regarding the descriptors "cremated teeth; violence; Forensic Odontology; ID; DNA samples; dental pulp". <em><strong>Results:</strong></em> Most authors reported the resistance of dental tissues when subjected to high temperatures and others showed the success of the identification through dental comparisons. <em><strong>Conclusions:</strong></em> A successful identification evidenced by DNA extracted from bone and dental remains. The literature reviewed suggests that up to certain temperatures, can be carried out identification by forensic genetics of cremated victims by DNA contained in dental pulp. Strict national referencing was observed in the physical characteristics or incinerated dental macroscopic bodies.</p>
Stability Analysis of Chaotic Wavy Stratified Fluid-Fluid Flow With the 1D Fixed-Flux Two-Fluid Model
Authors: Vaidheeswaran Avinash , Fullmer William D. , Chetty Krishna , Marino Raul G. , Lopez de Bertodano Martin 
Published: December 2016

The one-dimensional fixed-flux two-fluid model (TFM) is used to analyze the stability of the wavy interface in a slightly inclined pipe geometry. The model is reduced from the complete 1-D TFM, assuming a constant total volumetric flux, which resembles the equations of shallow water theory (SWT). From the point of view of two-phase flow physics, the Kelvin-Helmholtz instability, resulting from the relative motion between the phases, is still preserved after the simplification. Hence, the numerical fixed-flux TFM proves to be an effective tool to analyze local features of two-phase flow, in particular the chaotic behavior of the interface.
Experiments on smooth- and wavy-stratified flows with water and gasoline were performed to understand the interface dynamics. The mathematical behavior concerning the well-posedness and stability of the fixed-flux TFM is first addressed using linear stability theory. The findings from the linear stability analysis are also important in developing the eigenvalue based donoring flux-limiter scheme used in the numerical simulations. The stability analysis is extended past the linear theory using nonlinear simulations to estimate the Largest Lyapunov Exponent which confirms the non-linear boundedness of the fixed-flux TFM. Furthermore, the numerical model is shown to be convergent using the power spectra in Fourier space. The nonlinear results are validated with the experimental data. The chaotic behavior of the interface from the numerical predictions is similar to the results from the experiments.
Implicit LES Applied to Isothermal Swirling Coaxial Jets
Authors: Parra-Santos Teresa , Szasz Robert Z. , Pérez J. Rubén , Vuorinen Ville , Castro Francisco 
Published: December 2016

This work is devoted to the analysis of the interaction of two coaxial jet with swirling flow using Large Eddy Simulation methodology to reproduce the case of Roback and Johnson. The eight - flat - vanes in the annular nozzle are the precursor of the swirling annular jet with high swirl number.
An implicit LES model was used, this model uses mesh size as filter width so no sub-grid model is required. It is the numerical error who plays the role of dissipative part of the stress tensor in the sub-mesh. Mesh prerequisites are Δy+ = 1 and uniform hexahedral mesh. The resolution scheme used is a Total Variation Diminishing (TVD) with coefficients looking for good precision. PISO is the pressure-velocity coupling used. Besides, multigrid resolution improves the performance towards the full convergence.
Influence of the swirl number on the flow pattern is analyzed. Also the impact of conical diffuser on the mixing is presented.
Practical Learning on Computational Fluid Dynamics at Undergraduate Level
Authors: Parra-Santos Teresa , Molina Jordá José M. , Luna-Sandoval Gabriel , Cacho-Perez Mariano , Pérez J. Rubén 
Published: December 2016

This work involves a methodology for Mechanical Engineering students to learn Computational Fluid Dynamics playing an active role. Students carry out a fluid mechanics down scaled projects with the steps of sensibility of mesh, convergence of numerical algorithm, validation of turbulence model and description of flow patterns. Furthermore, they develop their critical thought when they identify weak points susceptible for improvement.
The offer of benchmark test cases ranges from head loses, driven cavities, swirling flows, to external aerodynamics. Simplifications to the level of undergraduate courses imply two dimensional simulations and a limited number of grid points. Hence, the assessment is based in coherence of decisions and efficient use of limited resources.
A review of the offer of workshops is supplied, such as the Ahmed car, the Roback and Johnson burner, aerodynamics of different NACA airfoils, and different geometries of driven cavities. These are classical test cases of numerical research and a sample of applications in wind energy, industrial furnaces, and lubrication.
Parametrization based in geometry, Reynolds number, Pitch angle among other, let simulate different flow patterns with similar degree of difficulty.
There is a deeper understanding of the topic when students need to discuss the strategies to accomplish the project, they need to write a technical report and finally they need to justify the evaluation of other works. Also, it is important to link the simplified projects of the workshop with the real world and the industrial applications.
Coalescence Prevention Algorithm for Level Set Method
Authors: Talley Matthew L. , Zimmer Matthew D. , Bolotnov Igor A. 
Published: December 2016

The application of interface tracking methods to bubbly flow modeling has grown in recent years due to improvements in computing performance and development of more efficient solvers. However, the standard formulation of most interface tracking methods is not designed to physically handle the interface interactions at reasonable grid sizes. Regardless of the method used, a high grid resolution is required in the liquid film region in order to properly model drainage process during bubble interaction, which in certain conditions prevents the coalescence. This makes large scale (many bubbles) simulations unaffordable. One of the popular interface tracking approached is the level-set (LS) method. To simulate realistic bubble coalescence behavior in the LS method an algorithm with the capability of delaying or preventing the process of multiple simultaneous coalescence events has been developed.
Bubble interaction plays a significant role in high void fraction flow behavior and affects the transition to other flow regimes (e.g. churn-turbulent or slug flows). The described algorithm allows to improve the accuracy of predicting coalescence events in these relevant cases and has been tested in a variety of conditions and computational meshes.
This novel algorithm uses the LS method field to detect when bubbles are in close proximity, indicating a potential coalescence event, and applies a subgrid scale force to simulate the unresolved liquid drainage force. The subgrid-model is introduced by locally modifying the surface tension force near the liquid film drainage area. The algorithm can also simulate the liquid drainage time of the thin film by controlling the length of time the increased surface tension has been applied. Thus a new method of modeling bubble coalescence has been developed.
Several test cases were designed to demonstrate the capabilities of the algorithm. The simulations, including a mesh study, confirmed the abilities to identify and prevent coalescence as well as implement the time tracking portion, with an additional 10–25% computational cost. Ongoing tests aim to verify the algorithm’s functionality for simulations with different flow conditions, a ranging number of bubbles, and both structured and unstructured computational mesh types. Specifically, a bubble rising towards a free surface provides a test of performance and demonstrates the ability to consistently prevent coalescence. In addition, a two bubble case and a seven bubble case provide a more complex demonstration of how the algorithm performs for larger simulations. These cases are compared to much more expensive simulations capable of resolving the liquid film drainage (through very high local mesh resolution), to investigate how the algorithm replicates the liquid film drainage process.
Interface Tracking Simulation of Phase-Change Phenomena: Boiling and Condensation Verification
Authors: Li Mengnan , Bolotnov Igor A. 
Published: December 2016

Interface tracking simulation (ITS) is one of the promising approaches to describe heat transfer of boiling phenomena and their underlying mechanisms. Better understanding and modeling of this process will benefit various engineering systems. In modern nuclear reactors, study on nucleate boiling phenomena is very important for the prediction of the Critical Heat Flux (CHF) phenomena.
The presented research will implement and verify the capability of evaporation process modeling by the massively parallel research code, PHASTA. The comparison of the numerical results and the analytical results demonstrates that the overall behavior of the simulation compares well with the analytical solution. A second simulation of the single bubble growth with non-uniform temperature distribution demonstrates both condensation and evaporation modeling. In the third simulation flow boiling capabilities were preliminary tested with laminar flow demonstration case. These results will be applied to a larger scale, multi-bubble simulations and help modeling of nucleate boiling phenomena.
Parametric Analysis of Erosion in 90 Degree and Long Radius Bends
Authors: Zahedi Peyman , Karimi Soroor , Mahdavi Marzieh , McLaury Brenton S. , Shirazi Siamack A. 
Published: December 2016

Solid particle erosion has been recognized as a major concern in the oil and gas production industry. It has been observed that erosion can cause serious and costly damage to equipment and pipelines. Accordingly, different studies have been performed in order to investigate erosion caused by solid particles entrained in the flow. Both experimental and modeling approaches have been used in the past to analyze solid particle erosion under different conditions to be able to mitigate these problems.
The goal of this paper is to use a Computational Fluid Dynamic (CFD) erosion model to predict erosion caused by particles flowing in 90 degree and long radius bends. The fluid flow model is coupled with a Lagrangian particle tracking approach. The CFD-based prediction procedure consists of three main steps: flow modeling, particle tracking and erosion calculation. The Reynolds Stress Model (RSM) is used as the turbulence model for all fluid flow simulations. Solid particles are injected from the inlet of the pipe and tracked throughout the bend. The effect of the number of particles released on the predicted maximum erosion magnitude has been investigated. In order to study the grid independency of the solution, erosion is predicted for 5 different grid spacings to accurately predict the flow and erosion rates. In order to assess the quality of the numerical predictions of the erosion rate, experimental data for single-phase (gas) flow with sand in a 3-inch pipe were used. The effects of particle size, fluid velocity, pipe diameter and radius as well as particle rebound model on erosion pattern and magnitude are also investigated. Comparison of these results with experimental erosion data demonstrates good agreement of the erosion trends.
It is found that the location of highest erosion for single-phase (gas) flow at low pressure containing sand is around 45° in the elbow. It has been also observed that the 300 μm particles cause approximately two times higher metal loss compared to the 150 μm particles. This higher erosion magnitude is not only caused by the increase in particle momentum but also by the significant increase in particle sharpness for the 300 μm sand. Moreover, simulation results indicate that the increase in gas superficial velocity leads to an increase in the erosion magnitude. According to the results, erosion ratios were reduced exponentially with the increase in pipe diameter at constant flow conditions and particle properties. Furthermore, two available rebound models in the literature were investigated, and simulations illustrate that both methods are in reasonable agreement with experimental data.
Development of an Efficient Phase Separator for Space and Ground Applications
Authors: Wu Xiongjun , Loraine Greg , Hsiao Chao-Tsung , Chahine Georges L. 
Published: December 2016

The limited amount of liquids and gases that can be carried to space makes it imperative to recycle and reuse these fluids for extended human operations. During recycling processes gas and liquid phases are often intermixed. In the absence of gravity, separating gases from liquids is challenging due to the absence of buoyancy. This paper discusses a phase separator that is capable of efficiently and reliably separating gas-liquid mixtures of both high and low void fractions in a wide range of flow rates that is applicable to reduced and zero gravity environments.
The phase separator consists of two concentric cylindrical chambers. The fluid introduced in the space between the two cylinders enters the inner cylinder through tangential slots and generates a high intensity swirling flow. The geometric configuration is selected to make the vortex swirl intense enough to lead to early cavitation which forms a cylindrical vaporous core at the axis even at low flow rates. Taking advantage of swirl and cavitation, the phase separator can force gas out of the liquid into the central core of the vortex even at low void fraction. Gas is extracted from one end of the cylinder axial region and liquid is extracted from the other end. The phase separator has successfully demonstrated its capability to reduce mixture void fractions down to 10−8 and to accommodate incoming mixture gas volume fractions as high as 35% in both earth and reduced gravity flight tests. The phase separator is on track to be tested by NASA on the International Space Station (ISS). Additionally, the phase separator design exhibits excellent scalability. Phase separators of different dimensions, with inlet liquid flow rates that range from a couple of GPMs to a few tens of GPMs, have been built and tested successfully in the presence and absence of the gravity.
Extensive ground experiments have been conducted to study the effects of main design parameters on the performance of the phase separator, such as the length and diameter of the inner cylinder; the size, location, and layout of injection slots and exit orifices, etc., on the swirling flow behavior, and on the gas extraction performance. In parallel, numerical simulations, utilizing a two-phase Navier-Stokes flow solver coupled with bubble dynamics, have been conducted extensively to facilitate the development of the phase separator. These simulations have enabled us to better understand the physics behind the phase separation and provided guideline for system parts optimization.
This paper describes our efforts in developing the passive phase separator for both space and ground applications.
Identification of a Novel Lincomycin Resistance Mutation Associated with Activation of Antibiotic Production in Streptomyces coelicolor A3(2)
Authors: Wang Guojun , Izawa Masumi , Yang Xiaoge , Xu Dongbo , Tanaka Yukinori , Ochi Kozo 
Published: December 2016

ABSTRACT

Comparative genome sequencing analysis of a lincomycin-resistant strain of
Streptomyces coelicolor
A3(2) and the wild-type strain identified a novel mutation conferring a high level of lincomycin resistance. Surprisingly, the new mutation was an in-frame DNA deletion in the genes
SCO4597
and
SCO4598
, resulting in formation of the hybrid gene
linR. SCO4597
and
SCO4598
encode two histidine kinases, which together with
SCO4596
, encoding a response regulator, constitute a unique two-component system. Sequence analysis indicated that these three genes and their arrangement patterns are ubiquitous among all
Streptomyces
genomes sequenced to date, suggesting these genes play important regulatory roles. Gene replacement showed that this mutation was responsible for the high level of lincomycin resistance, the overproduction of the antibiotic actinorhodin, and the enhanced morphological differentiation of this strain. Moreover, heterologous expression of the hybrid gene
linR
in
Escherichia coli
conferred resistance to lincomycin in this organism. Introduction of the hybrid gene
linR
in various
Streptomyces
strains by gene engineering technology may widely activate and/or enhance antibiotic production.
Effects of Increasing the Affinity of CarD for RNA Polymerase on Mycobacterium tuberculosis Growth, rRNA Transcription, and Virulence
Authors: Garner Ashley L. , Rammohan Jayan , Huynh Jeremy P. , Onder Lucas M. , Chen James , Bae Brian , Jensen Drake , Weiss Leslie A. , Manzano Ana Ruiz , Darst Seth A. , Campbell Elizabeth A. , Nickels Bryce E. , Galburt Eric A. , Stallings Christina L. 
Published: December 2016

ABSTRACT

CarD is an essential RNA polymerase (RNAP) interacting protein in
Mycobacterium tuberculosis
that stimulates formation of RNAP-promoter open complexes. CarD plays a complex role in
M. tuberculosis
growth and virulence that is not fully understood. Therefore, to gain further insight into the role of CarD in
M. tuberculosis
growth and virulence, we determined the effect of increasing the affinity of CarD for RNAP. Using site-directed mutagenesis guided by crystal structures of CarD bound to RNAP, we identified amino acid substitutions that increase the affinity of CarD for RNAP. Using these substitutions, we show that increasing the affinity of CarD for RNAP increases the stability of the CarD protein in
M. tuberculosis
. In addition, we show that increasing the affinity of CarD for RNAP increases the growth rate in
M. tuberculosis
without affecting 16S rRNA levels. We further show that increasing the affinity of CarD for RNAP reduces
M. tuberculosis
virulence in a mouse model of infection despite the improved growth rate
in vitro
. Our findings suggest that the CarD-RNAP interaction protects CarD from proteolytic degradation in
M. tuberculosis
, establish that growth rate and rRNA levels can be uncoupled in
M. tuberculosis
and demonstrate that the strength of the CarD-RNAP interaction has been finely tuned to optimize virulence.

IMPORTANCE
Mycobacterium tuberculosis
, the causative agent of tuberculosis, remains a major global health problem. In order to develop new strategies to battle this pathogen, we must gain a better understanding of the molecular processes involved in its survival and pathogenesis. We have previously identified CarD as an essential transcriptional regulator in mycobacteria. In this study, we detail the effects of increasing the affinity of CarD for RNAP on transcriptional regulation, CarD protein stability, and virulence. These studies expand our understanding of the global transcription regulator CarD, provide insight into how CarD activity is regulated, and broaden our understanding of prokaryotic transcription.
Role of Ribonucleotide Reductase in Bacillus subtilis Stress-Associated Mutagenesis
Authors: Castro-Cerritos Karla Viridiana , Yasbin Ronald E. , Robleto Eduardo A. , Pedraza-Reyes Mario 
Published: December 2016

ABSTRACT

The Gram-positive microorganism
Bacillus subtilis
relies on a single class Ib ribonucleotide reductase (RNR) to generate 2′-deoxyribonucleotides (dNDPs) for DNA replication and repair. In this work, we investigated the influence of RNR levels on
B. subtilis
stationary-phase-associated mutagenesis (SPM). Since RNR is essential in this bacterium, we engineered a conditional mutant of strain
B. subtilis
YB955 (
hisC952 metB5 leu427
) in which expression of the
nrdEF
operon was modulated by isopropyl-β-
d
-thiogalactopyranoside (IPTG). Moreover, genetic inactivation of
ytcG
, predicted to encode a repressor (NrdR) of
nrdEF
in this strain, dramatically increased the expression levels of a transcriptional
nrdE-lacZ
fusion. The frequencies of mutations conferring amino acid prototrophy in three genes were measured in cultures under conditions that repressed or induced RNR-encoding genes. The results revealed that RNR was necessary for SPM and overexpression of
nrdEF
promoted growth-dependent mutagenesis and SPM. We also found that
nrdEF
expression was induced by H
2
O
2
and such induction was dependent on the master regulator PerR. These observations strongly suggest that the metabolic conditions operating in starved
B. subtilis
cells increase the levels of RNR, which have a direct impact on SPM.

IMPORTANCE
Results presented in this study support the concept that the adverse metabolic conditions prevailing in nutritionally stressed bacteria activate an oxidative stress response that disturbs ribonucleotide reductase (RNR) levels. Such an alteration of RNR levels promotes mutagenic events that allow
Bacillus subtilis
to escape from growth-limited conditions.