The simulation model of sucker rod string transverse vibration under the space buckling deformation excitation and rod-tubing eccentric wear in vertical wells

Considering the limitations of the static buckling theory on the eccentric wear of sucker rod and tubing, a new dynamic analysis method for the transverse vibration of sucker rod in the tubing is proposed. Taking the axial distribution load at the rod body and the dynamic load at the bottom into account, the dynamic model of transverse vibration is established based on the space buckling configuration of rod string which regarded as the deformation excitation during the down stroke. To solve the mathematical equations, the finite difference method is used to discretize the well depth, and the Newmark-beta method is used to discretize the time. Meanwhile, a restitution coefficient is introduced to depict the change of velocity and the momentum after the collision. The result shows the phenomenon of rod-tubing collision occurs mainly in the down stroke after the rod string post buckling; the collision force from the wellhead to the bottom increases gradually, of which distributed almost along the entire well depth; and the high frequency collision occurs below the neutral point where the collision force is also the biggest. Further, the collision frequency and the collision force decrease successively from the neutral point to the wellhead direction. But during the up stroke, few collisions occur, and the collision force is also very small. The simulation model is suitable for the eccentric wear analysis of rod-tubing, and provides a new theoretical basis for the optimal allocation of the centralizer

Effects of doe-litter separation on intestinal bacteria, immune response and morphology of suckling rabbits

[EN] Gut development is stimulated by exposure to microorganisms, especially early-life microbial exposure. This study aimed to investigate whether doe-litter separation, which is performed in many rabbit farms, affects this exposure and therefore inhibits the development of intestinal system in suckling rabbits. Immediately after parturition, Rex rabbit does (n=16) were adjusted to 8 kits per litter and divided into doe-litter separation (DLS) group and doe-litter together (DLT) group based on the conditions of the does. One healthy kit per litter was selected and sacrificed at 7 d, 14 d, 21 d and 28 d of age, and the number of total bacteria, Escherichia coli and Bacteroides-Prevotella, expression of interleukin 6 (IL-6) and interleukin 10 (IL-10) in duodenum and caecum were investigated by real-time polymerase chain reaction. The morphological parameters of duodenum and vermiform appendix were also measured. Our results showed that doe-litter separation affected the number of intestinal bacteria. At 7 d of age, except for caecal Escherichia coli, the number of the investigated bacteria was decreased by doe-litter separation (P<0.05). But 1 wk later, only the number of total bacteria and Bacteroides-Prevotella in caecal content (P<0.05) and Escherichia coli in duodenal content from DLS kits (P<0.05) were still lower than those from DLT kits. After being provided with supplementary food for 7 d, DLS kits had fewer total bacteria in caecal content (P<0.05) and fewer E. coli in duodenal content (P<0.01) than DLT kits. After growing to 28 d of age, kits in DLS group still tended to have fewer total bacteria in caecal content, and expression of IL-10 and secretion of secretory IgA (sIgA) in vermiform appendix in DLS group was obviously lower than kits in DLT group (P<0.05). The villus height:crypt depth ratio in duodenum at 3rd wk and 4th wk was decreased by DLS (P<0.05). Kits in DLS group had shorter villus height (P<0.05), higher crypt depth (P<0.05) and shorter vermiform appendix (P<0.05) at the end of the trial. Furthermore, separating kits from the doe had a negative effect on their average daily gain at 3rd wk and 4th wk (P<0.05). Limiting the microbiological contact with the mother during suckling period affected the kits’ intestinal flora and could negatively affect the development of intestinal digestive and immune system and growth performance of kits.This study was funded by Key Science and Technology Programme of Shaanxi Province (No, 2013K02-18).Zhang, Y.; Cui, H.; Sun, D.; Liu, L.; Xu, X. (2018). Effects of doe-litter separation on intestinal bacteria, immune response and morphology of suckling rabbits. World Rabbit Science. 26(1):71-79. https://doi.org/10.4995/wrs.2018.5917SWORD717926

Brain Cleanup as a Potential Target for Poststroke Recovery: The Role of RXR (Retinoic X Receptor) in Phagocytes

Background and Purpose- Phagocytic cells, such as microglia and blood-derived macrophages, are a key biological modality responsible for phagocytosis-mediated clearance of damaged, dead, or displaced cells that are compromised during senescence or pathological processes, including after stroke. This process of clearance is essential to eliminate the source of inflammation and to allow for optimal brain repair and functional recovery. Transcription factor, RXR (retinoic-X-receptor) is strongly implicated in phagocytic functions regulation, and as such could represent a novel target for brain recovery after stroke. Methods- Primary cultured microglia and bone marrow macrophages were used for phagocytic study. Mice with deleted RXR-α in myeloid phagocytes (Mac-RXR-α-/-) were subjected to transient middle cerebral artery occlusion to mimic ischemic stroke and then treated with RXR agonist bexarotene. RNA-sequencing and long-term recovery were evaluated. Results- Using cultured microglia, we demonstrated that the RXR-α promotes the phagocytic functions of microglia toward apoptotic neurons. Using mice with deleted RXR-α in myeloid phagocytes (Mac-RXR-α-/-), we have shown that despite behaving similarly to the control at early time points (up to 3 days, damage established histologically and behaviorally), these Mac-RXR-α-/- mice demonstrated worsened late functional recovery and developed brain atrophy that was larger in size than that seen in control mice. The RXR-α deficiency was associated with reduced expression of genes known to be under control of the prominent transcriptional RXR partner, PPAR (peroxisome proliferator-activated receptor)-γ, as well as genes encoding for scavenger receptors and genes that signify microglia/macrophages polarization to a reparative phenotype. Finally, we demonstrated that the RXR agonist, bexarotene, administered as late as 1 day after middle cerebral artery occlusion, improved neurological recovery, and reduced the atrophy volume as assessed 28 days after stroke. Bexarotene did not improve outcome in Mac-RXR-α-/- mice. Conclusions- Altogether, these data suggest that phagocytic cells control poststroke recovery and that RXR in these cells represents an attractive target with exceptionally long therapeutic window.This work was supported by grant from the National Institutes of Health (NINDS) 1R01NS084292 to Dr Aronowski. Additional funding from Spanish Ministerio de Ciencia, Innovación y Universidades (MCNU) (SAF2017-90604-REDT-NurCaMeln, RTI2018-095928-B-I00) to Dr Ricote permitted to study RXR (retinoic-X-receptor) deletion in the phagocytic cells. The Centro Nacional de Investigaciones Cardiovasculares is supported by the Instituto de Salud Carlos III (ISCIII), the MCNU, and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

Study on the growth mechanism of the internal oxide layer in 9% Ni cryogenic steel

The oxidation behavior of the Ni-rich layer in the internal oxide layer (IOL) in 9% Ni cryogenic steel is investigated at 1,150°C for 0–240 min in the air atmosphere. The morphology and phase composition of the Ni—rich layer are analyzed with energy dispersive spectroscopy, scanning electron microscopy, metallographic microscopy, and X—ray diffraction. The results show that the Ni—rich layer mainly consists of gray Fe3O4/FeO and white Ni–Fe particles, with a small amount of black Fe2SiO4. The morphologies of Ni–Fe particles undergo the following changes with isothermal oxidation time: dot—like → strip—like → net-like; at the same time, layered Ni–Fe particles were formed at about 1/3 of the thickness of the Ni—rich layer. Compared with the dot-like Ni–Fe particle, the net-like and layered Ni–Fe particles provide a fast path for the diffusion of O in the Ni—rich layer. However, the experimental steel still has a much lower oxidation rate because of the hindrance of Ni–Fe particles on the out-diffusion of Fe. During the oxidation process, the Kirkendall effect induces pores/cavities in the IOL, which weakens the stability of the IOL. In the end, the spalling phenomenon of the layered Ni–Fe particle occurs at 1,150°C for 180 min

Connections Between Connexins, Calcium, and Cataracts in the Lens

There is a good deal of evidence that the lens generates an internal micro circulatory system, which brings metabolites, like glucose, and antioxidants, like ascorbate, into the lens along the extracellular spaces between cells. Calcium also ought to be carried into the lens by this system. If so, the only path for Ca2+ to get out of the lens is to move down its electrochemical gradient into fiber cells, and then move by electrodiffusion from cell to cell through gap junctions to surface cells, where Ca-ATPase activity and Na/Ca exchange can transport it back into the aqueous or vitreous humors. The purpose of the present study was to test this calcium circulation hypothesis by studying calcium homeostasis in connexin (Cx46) knockout and (Cx46 for Cx50) knockin mouse lenses, which have different degrees of gap junction coupling. To measure intracellular calcium, FURA2 was injected into fiber cells, and the gradient in calcium concentration from center to surface was mapped in each type of lens. In wild-type lenses the coupling conductance of the mature fibers was ∼0.5 S/cm2 of cell to cell contact, and the best fit to the calcium concentration data varied from 700 nM in the center to 300 nM at the surface. In the knockin lenses, the coupling conductance was ∼1.0 S/cm2 and calcium varied from ∼500 nM at the center to 300 nM at the surface. Thus, when the coupling conductance doubled, the concentration gradient halved, as predicted by the model. In knockout lenses, the coupling conductance was zero, hence the efflux path was knocked out and calcium accumulated to ∼2 μM in central fibers. Knockout lenses also had a dense central cataract that extended from the center to about half the radius. Others have previously shown that this cataract involves activation of a calcium-dependent protease, Lp82. We can now expand on this finding to provide a hypothesis on each step that leads to cataract formation: knockout of Cx46 causes loss of coupling of mature fiber cells; the efflux path for calcium is therefore blocked; calcium accumulates in the central cells; at concentrations above ∼1 μM (from the center to about half way out of a 3-wk-old lens) Lp82 is activated; Lp82 cleaves cytoplasmic proteins (crystallins) in central cells; and the cleaved proteins aggregate and scatter light

A Comparison of Molecular Biology Mechanism of Shewanella putrefaciens between Fresh and Terrestrial Sewage Wastewater

Municipal and industrial wastewater is often discharged into the environment without appropriate treatment, especially in developing countries. As a result, many rivers and oceans are contaminated. It is urgent to control and administer treatments to these contaminated rivers and oceans. However, most mechanisms of bacterial colonization in contaminated rivers and oceans were unknown, especially in sewage outlets. We found Shewanella putrefaciens to be the primary bacteria in the terrestrial sewage wastewater outlets around Ningbo City, China. Therefore, in this study, we applied a combination of differential proteomics, metabolomics, and real-time fluorescent quantitative PCR techniques to identify bacteria intracellular metabolites. We found S. putrefaciens had 12 different proteins differentially expressed in freshwater culture than when grown in wastewater, referring to the formation of biological membranes (Omp35, OmpW), energy metabolism (SOD, deoxyribose-phosphate pyrophosphokinase), fatty acid metabolism (beta-ketoacyl synthase), secondary metabolism, TCA cycle, lysine degradation (2-oxoglutarate reductase), and propionic acid metabolism (succinyl coenzyme A synthetase). The sequences of these 12 differentially expressed proteins were aligned with sequences downloaded from NCBI. There are also 27 differentially concentrated metabolites detected by NMR, including alcohols (ethanol, isopropanol), amines (dimethylamine, ethanolamine), amino acids (alanine, leucine), amine compounds (bilinerurine), nucleic acid compounds (nucleosides, inosines), organic acids (formate, acetate). Formate and ethanolamine show significant difference between the two environments and are possibly involved in energy metabolism, glycerophospholipid and ether lipids metabolism to provide energy supply and material basis for engraftment in sewage. Because understanding S. putrefaciens’s biological mechanism of colonization (protein, gene express and metabolites) in terrestrial sewage outlets is so important to administering and improving contaminated river and to predicting and steering performance, we delved into the biological mechanism that sheds light on the effect of environmental conditions on metabolic pathways

Genome-wide identification and expression analysis of the MYB transcription factor in moso bamboo (Phyllostachys edulis)

The MYB family, one of the largest transcription factor (TF) families in the plant kingdom, plays vital roles in cell formation, morphogenesis and signal transduction, as well as responses to biotic and abiotic stresses. However, the underlying function of bamboo MYB TFs remains unclear. To gain insight into the status of these proteins, a total of 85 PeMYBs, which were further divided into 11 subgroups, were identified in moso bamboo (Phyllostachys edulis) by using a genome-wide search strategy. Gene structure analysis showed that PeMYBs were significantly different, with exon numbers varying from 4 to 13. Phylogenetic analysis indicated that PeMYBs clustered into 27 clades, of which the function of 18 clades has been predicted. In addition, almost all of the PeMYBs were differently expressed in leaves, panicles, rhizomes and shoots based on RNA-seq data. Furthermore, qRT-PCR analysis showed that 12 PeMYBs related to the biosynthesis and deposition of the secondary cell wall (SCW) were constitutively expressed, and their transcript abundance levels have changed significantly with increasing height of the bamboo shoots, for which the degree of lignification continuously increased. This result indicated that these PeMYBs might play fundamental roles in SCW thickening and bamboo shoot lignification. The present comprehensive and systematic study on the members of the MYB family provided a reference and solid foundation for further functional analysis of MYB TFs in moso bamboo

Sex-Based Differences in Gut Microbiota Composition in Response to Tuna Oil and Algae Oil Supplementation in a D-galactose-Induced Aging Mouse Model

Our previous work indicated that a mixture of tuna oil and algae oil treatment in male mice effectively relieved D-galactose (D-gal)-induced aging and resulted in gut microbiota alterations, and that the best anti-aging effects were observed for a tuna oil to algae oil ratio of 1:2. However, the possibility of a sex-based difference in the anti-aging effect of the tuna oil and algae oil mixture or gut microbiota variation, has rarely been investigated. In this study, the anti-aging effect of an oil mixture (1:2) in male and female mice was measured, and oil treatment improved the learning and cognition of mice that were damaged by D-gal, increased the activities of anti-oxidative enzymes, and decreased the level of MDA, which acted as a hallmark of oxidative damage to lipids. Male mice showed better anti-aging effects than female mice with a specific oil mixture ratio, and the clinical drug donepezil showed a similar or better effect on aging alleviation than oil treatments in both sexes. On the other hand, the same oil treatment led to different gut microbiota composition alterations in male and female mice. Redundancy analysis (RDA) identified 31 and 30 key operational taxonomic units (OTUs) in the male and female mice, respectively, and only three of these OTUs overlapped. Moreover, the abundance of Lactobacillus and several probiotic-like butyric acid producers was higher in male mice than in female mice, whereas the abundance of some inflammation-related genera, such as Clostridium XlVa, was lower in male mice. In conclusion, this study indicated the sex-based differences related to the anti-aging effects of tuna oil and algae oil treatment are accompanied by sex-based differences in gut microbiota modulation

Comparison of osteogenic capability of 3D-printed bioceramic scaffolds and granules with different porosities for clinical translation

Pore parameters, structural stability, and filler morphology of artificial implants are key factors influencing the process of bone tissue repair. However, the extent to which each of these factors contributes to bone formation in the preparation of porous bioceramics is currently unclear, with the two often being coupled. Herein, we prepared magnesium-doped wollastonite (Mg-CSi) scaffolds with 57% and 70% porosity (57-S and 70-S) via a 3D printing technique. Meanwhile, the bioceramic granules (57-G and 70-G) with curved pore topography (IWP) were prepared by physically disrupting the 57-S and 70-S scaffolds, respectively, and compared for in vivo osteogenesis at 4, 10, and 16 weeks. The pore parameters and the mechanical and biodegradable properties of different porous bioceramics were characterized systematically. The four groups of porous scaffolds and granules were then implanted into a rabbit femoral defect model to evaluate the osteogenic behavior in vivo. 2D/3D reconstruction and histological analysis showed that significant bone tissue production was visible in the central zone of porous granule groups at the early stage but bone tissue ingrowth was slower in the porous scaffold groups. The bone tissue regeneration and reconstruction capacity were stronger after 10 weeks, and the porous architecture of the 57-S scaffold was maintained stably at 16 weeks. These experimental results demonstrated that the structure-collapsed porous bioceramic is favorable for early-stage osteoconduction and that the 3D topological scaffolds may provide more structural stability for bone tissue growth for a long-term stage. These findings provide new ideas for the selection of different types of porous bioceramics for clinical bone repair