Salt-induced osmotic stress for lipid overproduction in batch culture of Chlorella vulgaris

Effect of NaCl-induced osmotic stress on lipid production was investigated in batch culture of Chlorella vulgaris. Based on the facts that NaCl stress improved lipid production but inhibited cells growth at the same times, the novel strategies of multiple osmotic stresses with different NaCl additions (2 g/L at 80 h, 4 g/L at 100 h, and 6 g/L at 120 h) were adopted for lipid overproduction. Results show that after 180 h cultivation, lipid yield reached 3.16 g/L and intracellular lipid content was 58.6%, increased by 21.1 and 22.9%, respectively, compared to the control. Further applying the strategies to 5 L fermentor, lipid yield of 3.81 g/L was achieved at 180 h, which was 30.1% higher than the control, suggesting application of osmotic stress to lipid overproduction as being feasible.Key words: NaCl-induced osmotic stress, heterotrophic cultivation, lipid, glucose, Chlorella vulgaris

Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor

The latest discovery of high temperature superconductivity signature in single-layer FeSe is significant because it is possible to break the superconducting critical temperature ceiling (maximum Tc~55 K) that has been stagnant since the discovery of Fe-based superconductivity in 2008. It also blows the superconductivity community by surprise because such a high Tc is unexpected in FeSe system with the bulk FeSe exhibiting a Tc at only 8 K at ambient pressure which can be enhanced to 38 K under high pressure. The Tc is still unusually high even considering the newly-discovered intercalated FeSe system A_xFe_{2-y}Se_2 (A=K, Cs, Rb and Tl) with a Tc at 32 K at ambient pressure and possible Tc near 48 K under high pressure. Particularly interesting is that such a high temperature superconductivity occurs in a single-layer FeSe system that is considered as a key building block of the Fe-based superconductors. Understanding the origin of high temperature superconductivity in such a strictly two-dimensional FeSe system is crucial to understanding the superconductivity mechanism in Fe-based superconductors in particular, and providing key insights on how to achieve high temperature superconductivity in general. Here we report distinct electronic structure associated with the single-layer FeSe superconductor. Its Fermi surface topology is different from other Fe-based superconductors; it consists only of electron pockets near the zone corner without indication of any Fermi surface around the zone center. Our observation of large and nearly isotropic superconducting gap in this strictly two-dimensional system rules out existence of node in the superconducting gap. These results have provided an unambiguous case that such a unique electronic structure is favorable for realizing high temperature superconductivity

Rudimentary G-Quadruplex-Based Telomere Capping In Saccharomyces Cerevisiae

Telomere capping conceals chromosome ends from exonucleases and checkpoints, but the full range of capping mechanisms is not well defined. Telomeres have the potential to form G-quadruplex (G4) DNA, although evidence for telomere G4 DNA function in vivo is limited. In budding yeast, capping requires the Cdc13 protein and is lost at nonpermissive temperatures in cdc13-1 mutants. Here, we use several independent G4 DNA-stabilizing treatments to suppress cdc13-1 capping defects. These include overexpression of three different G4 DNA binding proteins, loss of the G4 DNA unwinding helicase Sgs1, or treatment with small molecule G4 DNA ligands. In vitro, we show that protein-bound G4 DNA at a 3\u27 overhang inhibits 5\u27-\u3e 3\u27 resection of a paired strand by exonuclease I. These findings demonstrate that, at least in the absence of full natural capping, G4 DNA can play a positive role at telomeres in vivo

The expression of Gli3, regulated by HOXD13, may play a role in idiopathic congenital talipes equinovarus

<p>Abstract</p> <p>Background</p> <p>Idiopathic congenital talipes equinovarus (ICTEV) is a congenital limb deformity. Based on extended transmission disequilibrium testing, <it>Gli-Kruppel family member 3 </it>(<it>Gli3</it>) has been identified as a candidate gene for ICTEV. Here, we verify the role of <it>Gli3 </it>in ICTEV development.</p> <p>Methods</p> <p>Using the rat ICTEV model, we analyzed the differences in <it>Gli3 </it>expression levels between model rats and normal control rats. We used luciferase reporter gene assays and ChIP/EMSA assays to analyze the regulatory elements of <it>Gli3</it>.</p> <p>Results</p> <p><it>Gli3 </it>showed higher expression levels in ICTEV model rats compared to controls (P < 0.05). We identified repressor and activator regions in the rat <it>Gli3 </it>promoter. The <it>Gli3 </it>promoter also contains two putative Hoxd13 binding sites. Using EMSA, the Hoxd13 binding site 2 was found to directly interact with Hoxd13 <it>in vitro</it>. ChIP assays of the Hoxd13-<it>Gli3 </it>promoter complex from a developing limb confirmed that endogenous Hoxd13 interacts with this region <it>in vivo</it>.</p> <p>Conclusion</p> <p>Our findings suggest that <it>HoxD13 </it>directly interacts with the promoter of <it>Gli3</it>. The increase of <it>Gli3 </it>expression in ICTEV model animal might result from the low expression of <it>HoxD13</it>.</p

Nanoscratch Characterization of GaN Epilayers on c- and a-Axis Sapphire Substrates

In this study, we used metal organic chemical vapor deposition to form gallium nitride (GaN) epilayers on c- and a-axis sapphire substrates and then used the nanoscratch technique and atomic force microscopy (AFM) to determine the nanotribological behavior and deformation characteristics of the GaN epilayers, respectively. The AFM morphological studies revealed that pile-up phenomena occurred on both sides of the scratches formed on the GaN epilayers. It is suggested that cracking dominates in the case of GaN epilayers while ploughing during the process of scratching; the appearances of the scratched surfaces were significantly different for the GaN epilayers on the c- and a-axis sapphire substrates. In addition, compared to the c-axis substrate, we obtained higher values of the coefficient of friction (μ) and deeper penetration of the scratches on the GaN a-axis sapphire sample when we set the ramped force at 4,000 μN. This discrepancy suggests that GaN epilayers grown on c-axis sapphire have higher shear resistances than those formed on a-axis sapphire. The occurrence of pile-up events indicates that the generation and motion of individual dislocation, which we measured under the sites of critical brittle transitions of the scratch track, resulted in ductile and/or brittle properties as a result of the deformed and strain-hardened lattice structure

Tire Defect Detection Based on Faster R-CNN

The tire defect detection method can help the rehabilitation robot to achieve autonomous positioning function and improve the accuracy of the robot system behavior. Defects such as foreign matter sidewall, foreign matter tread, and sidewall bubbles will appear in the process of tire production, which will directly or indirectly affect the service life of the tire. Therefore, a novel and efficient tire defect detection method was proposed based on Faster R-CNN. At preprocessing stage, the Laplace operator and the homomorphic filter were used to sharpen and enhance the data set, the gray values of the image target and the background were significantly different, which improved the detection accuracy. Moreover, data expansion was used to increase the number of images and improve the robustness of the algorithm. To promote the accuracy of the position detection and identification, the proposed method combined the convolution features of the third layer and the convolution features of the fifth layer in the ZF network (a kind of convolution neural network). Then, the improved ZF network was used to extract deep characteristics as inputs for Faster R-CNN. From the experiment, the proposed faster R-CNN defect detection method can accurately classify and locate the tire X-ray image defects, and the average test recognition rate is up to 95.4%. Moreover, if there are additional types of defects that need to be detected, then a new detection model can be obtained by fine-tuning the network

Specification and guideline for technical aspects and scanning parameter settings of neonatal lung ultrasound examination

Lung ultrasound (LUS) is now widely used in the diagnosis and monitor of neonatal lung diseases.Nevertheless, in the published literatures,the LUS images may display a significant variation in technical execution,while scanning parameters may influence diagnostic accuracy.The inter- and intra-observer reliabilities of ultrasound exam have been extensively studied in general and in LUS.As expected,the reliability declines in the hands of novices when they perform the point-of-care ultrasound (POC US).Consequently,having appropriate guidelines regarding to technical aspects of neonatal LUS exam is very important especially because diagnosis is mainly based on interpretation of artifacts produced by the pleural line and the lungs.The present work aimed to create an instrument operation specification and parameter setting guidelines for neonatal LUS.Technical aspects and scanning parameter settings that allow for standardization in obtaining LUS images include (1)select a high-end equipment with high-frequency linear array transducer (12-14 MHz).(2)Choose preset suitable for lung examination or small organs.(3)Keep the probe perpendicular to the ribs or parallel to the intercostal space.(4)Set the scanning depth at 4-5 cm.(5)Set 1-2 focal zones and adjust them close to the pleural line.(6)Use fundamental frequency with speckle reduction 2-3 or similar techniques.(7)Turn off spatial compounding imaging.(8)Adjust the time-gain compensation to get uniform image from the near-to far-field

Observation of superconductivity at 30 K~46 K in AxFe2Se2 (A = Li, Na, Ba, Sr, Ca, Yb, and Eu)

New iron selenide superconductors by intercalating smaller-sized alkali metals (Li, Na) and alkaline earths using high-temperature routes have been pursued ever since the discovery of superconductivity at about 30 K in KFe2Se2, but all have failed so far. Here we demonstrate that a series of superconductors with enhanced Tc=30~46 K can be obtained by intercalating metals, Li, Na, Ba, Sr, Ca, Yb, and Eu in between FeSe layers by the ammonothermal method at room temperature. Analysis on their powder X-ray diffraction patterns reveals that all the main phases can be indexed based on body-centered tetragonal lattices with a~3.755-3.831 {\AA} while c~15.99-20.54 {\AA}. Resistivities show the corresponding sharp transitions at 45 K and 39 K for NaFe2Se2 and Ba0.8Fe2Se2, respectively, confirming their bulk superconductivity. These findings provide a new starting point for studying the properties of these superconductors and an effective synthetic route for the exploration of new superconductors as well.Comment: 22 pages, 5 figure