65 research outputs found

    An Angular Position-Based Two-Stage Friction Modeling and Compensation Method for RV Transmission System

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    In RV transmission system (RVTS), friction is closely related to rotational speed and angular position. However, classical friction models do not consider the influence of angular position on friction, resulting in limited accuracy in describing the RVTS frictional behavior. For this reason, this paper proposes an angular position-based two-stage friction model for RVTS, and achieves a more accurate representation of friction of RVTS. The proposed model consists of two parts, namely pre-sliding model and sliding model, which are divided by the maximum elastic deformation recovery angle of RVTS obtained from loading-unloading tests. The pre-sliding friction behavior is regarded as a spring model, whose stiffness is determined by the angular position and the acceleration when the velocity crosses zero, while the sliding friction model is established by the angular-segmented Stribeck function, and the friction parameters of the adjacent segment are linearly smoothed. A feedforward compensation based on the proposed model was performed on the RVTS, and its control performance was compared with that using the classical Stribeck model. The comparison results show that when using the proposed friction model, the low-speed-motion smoothness of the RVTS can be improved by 14.2%, and the maximum zero-crossing speed error can be reduced by 37.5%, which verifies the validity of the proposed friction model, as well as the compensation method

    Transcatheter Arterial Embolization in the Treatment of Extensive Maxillofacial Hemangioma in Children

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    Abstract Infantile hemangioma frequently occurs in the maxillofacial region as an extensive mass involving many vital structures. As such, many children are found to have an unresectable hemangioma at the initial diagnosis. In the present study transcatheter arterial embolization (TAE) alone or in combination with surgery and local injection of bleomycin A has been attempted to improve the treatment of these lesions. The results of evaluating the effectiveness and therapeutic role of TAE in these extensive maxillofacial hemangiomas in children are presented. We retrospectively analyzed the records of 17 children with maxillofacial hemangioma treated between 1997 and 2004. Altogether, 17 patients (11 boys, 6 girls) were diagnosed as having an extensive maxillofacial hemangioma based on its clinical manifestation, color Doppler ultrasonography, and sometimes computed tomography. They underwent selective TAE alone or TAE followed by surgical excision. For the children with Kasabach-Merritt syndrome, systemic corticosteroid therapy was administered first. All the children had an excellent response after TAE treatment without obvious complications, and the size of the hemangioma body markedly decreased. Local injection of bleomycin A was then undertaken in four children and surgical removal in five. All the children achieved successful disappearance of the hemangioma, with no recurrence during the follow-up period of 5 to 86 months. TAE is thus a reliable and effective therapeutic choice for extensive maxillofacial hemangioma in children, alone or as a preoperative adjunctive measure. It improves the feasibility of complete resection and effects the disappearance of these potentially dangerous bulky tumors with little bleeding and few complications

    A Triad of Lys12, Lys41, Arg78 Spatial Domain, a Novel Identified Heparin Binding Site on Tat Protein, Facilitates Tat-Driven Cell Adhesion

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    Tat protein, released by HIV-infected cells, has a battery of important biological effects leading to distinct AIDS-associated pathologies. Cell surface heparan sulfate protoglycans (HSPGs) have been accepted as endogenous Tat receptors, and the Tat basic domain has been identified as the heparin binding site. However, findings that deletion or substitution of the basic domain inhibits but does not completely eliminate Tat–heparin interactions suggest that the basic domain is not the sole Tat heparin binding site. In the current study, an approach integrating computational modeling, mutagenesis, biophysical and cell-based assays was used to elucidate a novel, high affinity heparin-binding site: a Lys12, Lys41, Arg78 (KKR) spatial domain. This domain was also found to facilitate Tat-driven β1 integrin activation, producing subsequent SLK cell adhesion in an HSPG-dependent manner, but was not involved in Tat internalization. The identification of this new heparin binding site may foster further insight into the nature of Tat-heparin interactions and subsequent biological functions, facilitating the rational design of new therapeutics against Tat-mediated pathological events

    Extensive Crosstalk between O-GlcNAcylation and Phosphorylation Regulates Akt Signaling

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    O-linked N-acetylglucosamine glycosylations (O-GlcNAc) and O-linked phosphorylations (O-phosphate), as two important types of post-translational modifications, often occur on the same protein and bear a reciprocal relationship. In addition to the well documented phosphorylations that control Akt activity, Akt also undergoes O-GlcNAcylation, but the interplay between these two modifications and the biological significance remain unclear, largely due to the technique challenges. Here, we applied a two-step analytic approach composed of the O-GlcNAc immunoenrichment and subsequent O-phosphate immunodetection. Such an easy method enabled us to visualize endogenous glycosylated and phosphorylated Akt subpopulations in parallel and observed the inhibitory effect of Akt O-GlcNAcylations on its phosphorylation. Further studies utilizing mass spectrometry and mutagenesis approaches showed that O-GlcNAcylations at Thr 305 and Thr 312 inhibited Akt phosphorylation at Thr 308 via disrupting the interaction between Akt and PDK1. The impaired Akt activation in turn resulted in the compromised biological functions of Akt, as evidenced by suppressed cell proliferation and migration capabilities. Together, this study revealed an extensive crosstalk between O-GlcNAcylations and phosphorylations of Akt and demonstrated O-GlcNAcylation as a new regulatory modification for Akt signaling

    Molecular Mechanisms of Fiber Differential Development between G. barbadense and G. hirsutum Revealed by Genetical Genomics

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    Cotton fiber qualities including length, strength and fineness are known to be controlled by genes affecting cell elongation and secondary cell wall (SCW) biosynthesis, but the molecular mechanisms that govern development of fiber traits are largely unknown. Here, we evaluated an interspecific backcrossed population from G. barbadense cv. Hai7124 and G. hirsutum acc. TM-1 for fiber characteristics in four-year environments under field conditions, and detected 12 quantitative trait loci (QTL) and QTL-by-environment interactions by multi-QTL joint analysis. Further analysis of fiber growth and gene expression between TM-1 and Hai7124 showed greater differences at 10 and 25 days post-anthesis (DPA). In this two period important for fiber performances, we integrated genome-wide expression profiling with linkage analysis using the same genetic materials and identified in total 916 expression QTL (eQTL) significantly (P<0.05) affecting the expression of 394 differential genes. Many positional cis-/trans-acting eQTL and eQTL hotspots were detected across the genome. By comparative mapping of eQTL and fiber QTL, a dataset of candidate genes affecting fiber qualities was generated. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed the major differential genes regulating fiber cell elongation or SCW synthesis. These data collectively support molecular mechanism for G. hirsutum and G. barbadense through differential gene regulation causing difference of fiber qualities. The down-regulated expression of abscisic acid (ABA) and ethylene signaling pathway genes and high-level and long-term expression of positive regulators including auxin and cell wall enzyme genes for fiber cell elongation at the fiber developmental transition stage may account for superior fiber qualities

    CLTCP: An Adaptive TCP Congestion Control Algorithm Based on Congestion Level

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    MiR-34c regulates the proliferation and apoptosis of lung cancer cells

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    Purpose: As miR-34c acts as a tumor suppressant for multiple cancers, the purpose of this study was to investigate that role that miR-34c plays in the proliferation and apoptosis of lung cancer. Methods: The expression of miR-34c in 600 patients with lung cancer was quantitatively analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) technology and correlated to clinical pathological parameters. The CCK-8 analysis and flow cytometry were carried out to detect cell proliferation and apoptosis in miR-34c-mimic transfected cell lines. Moreover, the regulation of miR-34c to interleukin-6 (IL-6) in cell lines was detected by western blot, qRT-PCR and dual-luciferase reporter assay. Results: The expression of miR-34c was downregulated in lung cancer compared with adjacent normal tissues. The expression level of miR-34c was linked to stromal invasion. Furthermore, overexpressing miR-34c played an active role in effectively inhibiting cell proliferation and inducing apoptosis. In addition, a significant inverse relationship was exhibited between the expression of miR-34c and IL-6 in tumor tissues. Conclusion: At the molecular level, IL-6 can be used as a direct target of miR-34c in the treatment of lung cancer cells and miR-34c can be used as an effective biomarker and therapeutic target for lung cancer

    The Dewetting Properties of Lotus Leaves

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    EFFECT OF LIGNIN CONTENT ON ENZYMATIC HYDROLYSIS OF FURFURAL RESIDUES

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    The enzymatic saccharification of pretreated furfural residues with different lignin content was studied to verify the effect of lignin removal in the hydrolysis process. The results showed that the glucose yield was improved by increasing the lignin removal. A maximum glucose yield of 96.8% was obtained when the residue with a lignin removal of 51.4% was hydrolyzed for 108 h at an enzyme loading of 25 FPU/g cellulose. However, further lignin removal did not increase the hydrolysis. The effect of enzyme loading on the enzymatic hydrolysis was also explored in this work. It was concluded that a high glucose yield of 90% was achieved when the enzyme dosage was reduced from 25 to 15 FPU/g cellulose, which was cost-effective for the sugar and ethanol production. The structures of raw material and delignified samples were further characterized by XRD and scanning electron microscopy (SEM)
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