Design of Primers for Evaluation of Lactic Acid Bacteria Populations in Complex Biological Samples

Lactic acid bacteria (LAB) are important for human health. However, the relative abundance of LAB in complex samples, such as fecal samples, is low and their presence and diversity (at the species level) is understudied. Therefore, we designed LAB-specific primer pairs based on 16S rRNA gene consensus sequences from 443 species of LAB from seven genera. The LAB strains selected were genetically similar and known to play a role in human health. Prior to primer design, we obtained consistent sequences for the primer-binding sites by comparing the 16S rRNA gene sequences, manually identifying single-stranded primers and modifying these primers using degenerate bases. We assembled primer pairs with product sizes of >400 bp. Optimal LAB-specific primers were screened using three methods: PCR amplification, agarose gel electrophoresis and single-molecule real-time (SMRT) sequencing analysis. During the SMRT analysis procedure, we focused on sequence reads and diversity at the species level of target LAB in three fecal samples, using the universal bacterium primer 27f/1492r as a reference control. We created a phylogenetic tree to confirm the ability of the best candidate primer pair to differentiate amongst species. The results revealed that LAB-specific primer L5, with a product size of 750 bp, could generate 3222, 2552, and 3405 sequence reads from fecal Samples 1, 2, and 3. This represented 14, 13 and 10% of all target LAB sequence reads, respectively, compared with 2, 0.8, and 0.8% using the 27f/1492r primer. In addition, L5 detected LAB that were in low abundance and could not be detected using the 27f/1492r primer. The phylogenetic tree based on the alignments between the forward and reverse primer of L5 showed that species within the seven target LAB genera could be distinguished from each other, confirming L5 is a powerful tool for inferring phylogenetic relationships amongst LAB species. In conclusion, L5 is a LAB-specific primer that can be used for high-throughput sequencing and identification of taxa to the species level, especially in complex samples with relatively low LAB content. This enables further research on LAB population diversity in complex ecosystem, and on relationships between LAB and their hosts

Loss of Microstructural Integrity in the Limbic-Subcortical Networks for Acute Symptomatic Traumatic Brain Injury

Previous studies reported discrepant white matter diffusivity in mild traumatic brain injury (mTBI) on the base of Glasgow Coma Scale, which are unreliable for some TBI severity indicators and the frequency of missing documentation in the medical record. In the present study, we adopted the Mayo classification system for TBI severity. In this system, the mTBI is also divided into two groups as "probable and symptomatic" TBI. We aimed to investigate altered microstructural integrity in symptomatic acute TBI (<1 week) by using tract-based spatial statics (TBSS) approach. A total of 12 patients and 13 healthy volunteers were involved and underwent MRI scans including conventional scan, and SWI and DTI. All the patients had no visible lesions by using conventional and SWI neuroimaging techniques, while showing widespread declines in the fractional anisotropy (FA) of gray matter and white matter throughout the TBSS skeleton, particularly in the limbic-subcortical structures. By contrast, symptomatic TBI patients showed no significant enhanced changes in FA compared to the healthy controls. A better understanding of the acute changes occurring following symptomatic TBI may increase our understanding of neuroplasticity and continuing degenerative change, which, in turn, may facilitate advances in management and intervention

Visible Light Driven Spherical CuBi2O4 with Surface Oxygen Vacancy Enhanced Photocatalytic Activity: Catalyst Fabrication, Performance, and Reaction Mechanism

Here, a spherical CuBi2O4 catalyst with surface oxygen vacancy was fabricated through a facile hydrothermal method, which exhibited remarkable enhanced photocatalytic activity of refractory chemicals in the heterogeneous sulfate radical-based Fenton-like reaction under visible light emitting diode (LED) light irradiation. The property of the catalysts was systematically characterized by scanning electron microscopy (SEM)/high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV/vis methods. The effects of parameters of solution pH, potassium peroxymonosulfate (PMS) concentration, catalyst dosage, and catalyst reusability on Rhodamine B (RhB) degradation were investigated. In the interface reaction, the improved photodegradation efficiency could be attributed to the decomposition of PMS, which produced sulfate radicals and hydroxyl radicals owing to the transmission of photo-generated electron/hole pairs. Herein, the introduction of surface oxygen vacancy as well as the cycling of copper valence states (Cu(II)/Cu(I) pairs) can facilitate the production of free reactive radicals, leading to the high degradation efficiency. The catalyst showed high removal efficiency and presented good cycle stability in the reaction. Additionally, the free radical quencher experiment and electron spin resonance (EPR) experiments were conducted, and a proposed photocatalytic mechanism was also illustrated

Physical and Numerical Modelling on the Mixing Condition in a 50 t Ladle

The bubbly flow and mixing conditions for gas stirring in a 50t ladle were investigated by using physical modelling and mathematical modelling. In the physical modelling, the effect of the porous plugs' configurations on the tracer homogenization was studied by using a saturated NaCl solution to predict the mixing time and a color dye to show the mixing pattern. In the mathematical modelling, the Euler-Lagrange model and species transport model were used to predict the flow pattern and tracer homogenization, respectively. The results show that, for a +/- 5% homogenization degree, the mixing time with dual plugs using a radial angle of 180 degrees is shortest. In addition, the mixing time using a radial angle of 135 degrees decreases the most with an increased flow rate. The flow pattern and mixing conditions predicted by mathematical modelling agree well with the result of the physical modelling. For a +/- 1% homogenization degree, the influence of the tracer's natural convection on its homogenization pattern cannot be neglected. This is especially true for a 'soft bubbling' case using a low gas flow rate. Overall, it is recommended that large radial angles in the range of 135 degrees 180 degrees are chosen for gas stirring in the present study when using dual porous plugs.QC 20200115</p

Factors Affecting the Physical Properties of Edible Composite Film Prepared from Zein and Wheat Gluten

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Ultraviolet versus infrared : Effects of ablation laser wavelength on the expansion of laser-induced plasma into one-atmosphere argon gas

International audienceLaser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV : 355 nm) or infrared (IR : 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy

Simultaneous SERS Detection of Multiple Amino Acids Using ZIF-8@AuNPs as Substrate: Classified with 1D Convolutional Neural Network

Amino acids found in minor coarse cereals are essential for human growth and development and play a crucial role in efficient and rapid quantitative detection. Surface-enhanced Raman spectroscopy (SERS) enables nondestructive, efficient, and rapid sample detection. Traditional SERS detection efficiency is constrained by the use of a single target. In this study, three different amino acids (cysteine, valine, and tryptophan) were detected simultaneously using a ZIF-8@AuNPs composite substrate. The linear range of detection was 10−3 to 10−1 M, with limits of detection (LODs) of 2.40 × 10−4 M, 2.24 × 10−4 M, and 1.55 × 10−4 M, respectively. Same linear ranges and LODs were achieved with a one-dimensional convolutional neural network method. Furthermore, this substrate enabled the effective detection of amino acids in millet and efficient detection of cysteine in health products. This study presents a novel method for simultaneous detection of multiple analytes