船板命中率的影响因素及改进措施

简要介绍了韶钢二轧厂船板生产的工艺特点,对影响船板命中率的因素进行了分析,介绍了提高船板命中率的措施。     

全定尺生产模式在船板生产中的运用

全定尺生产模式在船板生产中的运用,极大地提高了船板命中率,有效降低了生产成本.     

提高船板双定尺命中率的措施

介绍了新余钢铁公司中板生产线的工艺流程，分析了影响生产船板双定命中率的因素，并介绍了采取的改进措施和取得的效果。     

船板质量缺陷成因及控制措施

主要结合首秦公司船板质量整改分析船板质量缺陷的成因,通过整改现场经验介绍船板质量缺陷的控制措施,同时介绍了国内外船板在质量、管理及信息系统等方面的差距,指出首秦公司下一步的改进方向。     

船板钢的成分性能要求及研究现状

船板钢作为船舶制造和海洋工程的核心材料之一,其性能与质量直接影响着海洋工业的可靠性和安全性。综述了特殊服役条件下对船板钢化学成分以及性能的要求,介绍了船板钢的开发特点以及国内外生产船板钢的关键技术,分析了船板钢未来的发展方向,旨在为钢铁企业船板钢的开发提供借鉴。     

影响船板合格率的因素及对策

本文简要介绍了提高中厚船板合格率的重要意义，重点介绍了影响船板合格率的因素及采用的相应措施。     

首钢船板钢热轧板卷的生产和使用

介绍了首钢迁钢公司开发生产船板钢热轧板卷的情况,分析了批量生产的船板钢热轧板卷的化学成分、力学性能、冶金质量和焊接性能,对开平矫直船板的残余应力研究进行了阐述。     

船板钢的发展与生产技术

介绍了船板钢的发展趋势、冶炼技术、成分控制、纯净度要求，对船板钢的轧制技术进行了概述，重点综述了高强度船板钢的生产技术。     

船板轧成率的影响因素及对策

本文简要介绍船板的技术特点，对影响船板轧成率的因素进行统计和分析，介绍提高船板轧成率的措施。     

浅谈提高船板强韧性的途径

对影响船板一次性合格率因素进行了分析，并介绍了坯料熔炼成分，轧制工艺参数的确定对船板强韧性的影响以及提高船板强韧性的途径。     

The inositol 5'-phosphatase SHIP binds to immunoreceptor signaling motifs and responds to high affinity IgE receptor aggregation

Immunoreceptors such as the high affinity IgE receptor, FcepsilonRI, and T-cell receptor-associated proteins share a common motif, the immunoreceptor tyrosine-based activation motif (ITAM). We used the yeast tribrid system to identify downstream effectors of the phosphorylated FcepsilonRI ITAM-containing subunits beta and gamma. One novel cDNA was isolated that encodes a protein that is phosphorylated on tyrosine, contains a Src-homology 2 (SH2) domain, inositolpolyphosphate 5-phosphatase activity, three NXXY motifs, several proline-rich regions, and is called SHIP. Mutation of the conserved tyrosine or leucine residues within the FcepsilonRI beta or gamma ITAMs eliminates SHIP binding and indicates that the SHIP-ITAM interaction is specific. SHIP also binds to ITAMs from the CD3 complex and T cell receptor zeta chain in vitro. SHIP protein possesses both phosphatidylinositol-3,4,5-trisphosphate 5'-phosphatase and inositol-1,3,4,5-tetrakisphosphate 5'-phosphatase activity. Phosphorylation of SHIP by a protein-tyrosine kinase, Lck, results in a reduction in enzyme activity. FcepsilonRI activation induces the association of several tyrosine phosphoproteins with SHIP. SHIP is constitutively tyrosine-phosphorylated and associated with Shc and Grb2. These data suggest that SHIP may serve as a multifunctional linker protein in receptor activation.     

The src homology 2-containing inositol phosphatase (SHIP) is the gatekeeper of mast cell degranulation

To clarify the role that the src homology 2-containing inositol phosphatase (SHIP) plays in mast cell degranulation, the gene for SHIP was disrupted by homologous recombination in embryonic stem cells. Bone-marrow-derived mast cells from SHIP+/+, +/-, and -/- F2 littermates were compared. SHIP-/- mast cells were found to be far more prone to degranulation, after the crosslinking of IgE preloaded cells, than SHIP+/- or +/+ cells. Intriguingly, IgE alone also stimulated massive degranulation in SHIP-/- but not in +/+ mast cells. This degranulation with IgE alone, which may be due to low levels of IgE aggregates, correlated with a higher and more sustained intracellular calcium level than that observed with SHIP+/+ cells and was dependent upon the entry of extracellular calcium. Immunoprecipitation studies revealed that the addition of IgE alone to normal mast cells stimulates multiple cascades, which are prevented from progressing to degranulation by SHIP. PI 3-kinase inhibitor studies suggested that IgE-induced activation of PI 3-kinase is upstream of the entry of extracellular calcium and that SHIP restricts this entry by hydrolyzing phosphatidylinositol 3,4, 5-trisphosphate. These results show the critical role that SHIP plays in setting the threshold for degranulation and that SHIP directly modulates a "positive-acting" receptor.     

Role of the inositol phosphatase SHIP in B cell receptor-induced Ca2+ oscillatory response

Src homology-2 domain-containing inositol polyphosphate 5'-phosphatase (SHIP) is a recently identified protein that has been implicated as an important signaling molecule. Although SHIP has been shown to participate in the FcgammaRIIB-mediated inhibitory signal, the functional role of SHIP in activation responses by immunoreceptor tyrosine-based activation motif-bearing receptors such as B cell receptor (BCR) remains unclear. Indeed, it has been proposed that SHIP serves as a linking molecule for the regulation of the extracellular signal-regulated kinase pathway in BCR signaling, because SHIP associates with Shc. We now report that SHIP-deficient DT40 B cells display enhanced Ca2+ mobilization in response to BCR ligation, whereas extracellular signal-regulated kinase activation is unaffected. This Ca2+ enhancement is due to a sustained intracellular Ca2+ increase or to long-lasting Ca2+ oscillations by loss of SHIP, as revealed by single-cell Ca2+ imaging analysis. These results demonstrate the importance of SHIP in B cell activation by the modulation of Ca2+ mobilization.     

Meta-synthesis of qualitative analyses of caring: defining a therapeutic model of nursing

SHIP is a SH2 domain-containing inositol polyphosphatase that is selectively tyrosine phosphorylated and associated with the adapter protein Shc in B lymphocytes upon co-crosslinking surface immunoglobulin and Fc gamma RIIB1. We previously observed that this stimulation condition is associated with a reduction in the interaction of Grb2 with phosphorylated Shc, an enhanced interaction of Shc with SHIP, and a block in the Ras signaling pathway. We proposed that the SH2 domain of SHIP competes with Grb2 in binding to phospho-Shc, resulting in a block in Ras signaling. To test this model, we examined the mode of SHIP-Shc interaction. Using recombinant Shc and SHIP interaction domains and purified Shc and SHIP phosphopeptides, we show that the interaction is bi-dentate such that the SH2 domain of SHIP recognizes phosphorylated Y317 and doubly-phosphorylated Y239/Y240 of Shc and the Shc PTB domain recognizes phosphorylated NPxpY motifs within SHIP. We observed no role for the Shc SH2 domain in the interaction. These findings are consistent with our earlier model that SHIP and Grb2 compete for binding to phospho-Shc and support the notion that, in addition to the hydrolysis of inositol phosphates and phospholipids, SHIP contributes to anti-proliferative biochemistry by blocking protein-protein interactions.     

Shc interaction with Src homology 2 domain containing inositol phosphatase (SHIP) in vivo requires the Shc-phosphotyrosine binding domain and two specific phosphotyrosines on SHIP

The adapter protein Shc has been implicated in mitogenic signaling via growth factor receptors, cytokine receptors, and antigen receptors on lymphocytes. Besides the well characterized interaction of Shc with molecules involved in Ras activation, Shc also associates with a 145-kDa tyrosine-phosphorylated protein upon triggering via antigen receptors and many cytokine receptors. This 145-kDa protein has been recently identified as an SH2 domain containing 5'-inositol phosphatase (SHIP) and has been implicated in the regulation of growth and differentiation in hematopoietic cells. In this report, we have addressed the molecular details of the interaction between Shc and SHIP in vivo. During T cell receptor signaling, tyrosine phosphorylation of SHIP and its association with Shc occurred only upon activation. We demonstrate that the phosphotyrosine binding domain of Shc is necessary and sufficient for its association with tyrosine-phosphorylated SHIP. Through site-directed mutagenesis, we have identified two tyrosines on SHIP, Tyr-917, and Tyr-1020, as the principal contact sites for the Shc-phosphotyrosine binding domain. Our data also suggest a role for the tyrosine kinase Lck in phosphorylation of SHIP. We also show that the SH2 domain of SHIP is dispensable for the Shc-SHIP interaction in vivo. These data have implications for the localization of the Shc.SHIP complex and regulation of SHIP function during T cell receptor signaling.     

Growth factors and insulin stimulate tyrosine phosphorylation of the 51C/SHIP2 protein

Antibodies raised against the 51C/SHIP2 inositol polyphosphate 5'-phosphatase were used to examine the effects of growth factors and insulin on the metabolism of this protein. Immunoblot analysis revealed that the 51C/SHIP2 protein was widely expressed in fibroblast and nonhematopoietic tumor cell lines, unlike the SHIP protein, which was found only in cell lines of hematopoietic origin. The 51C/SHIP2 antiserum precipitated a protein of approximately 145 kDa along with an activity which hydrolyzed phosphatidylinositol 3,4, 5-trisphosphate to phosphatidylinositol 3,4-bisphosphate. Tyrosine phosphorylation of the 51C/SHIP2 protein occurred in response to treatment of cells with epidermal growth (EGF), platelet-derived growth factor (PDGF), nerve growth factor (NGF), insulin-like growth factor-1 (IGF-1), or insulin. EGF and PDGF induced transient tyrosine phosphorylation of 51C/SHIP2, with maximal tyrosine phosphorylation occurring at 5-10 min following treatment and returning to near basal levels within 20 min. In contrast, treatment of cells with NGF, IGF-1, or insulin resulted in prolonged tyrosine phosphorylation of 51C/SHIP2 protein, with 40-80% maximal phosphorylation sustained for up to 2 h following agonist treatment. The kinetics of activation of the Akt/PKB protein kinase by the various factors correlated well with the kinetics of tyrosine phosphorylation of 51C/SHIP2. EGF, NGF, and PDGF stimulated the association of 51C/SHIP2 protein with the Shc adapter protein; however, no Shc could be detected in 51C/SHIP2-immune precipitates from cells treated with IGF-1 or insulin. The data suggest that 51C/SHIP2 may play a significant role in regulation of phosphatidylinositol 3'-kinase signaling by growth factors and insulin.     

Recruitment and phosphorylation of SH2-containing inositol phosphatase and Shc to the B-cell Fc gamma immunoreceptor tyrosine-based inhibition motif peptide motif

Recently, we and others have demonstrated that negative signaling in B cells selectively induces the tyrosine phosphorylation of a novel inositol polyphosphate phosphatase, p145SHIP. In this study, we present data indicating that p145SHIP binds directly a phosphorylated motif, immunoreceptor tyrosine-based inhibition motif (ITIM), present in the cytoplasmic domain of Fc gammaRIIB1. Using recombinant SH2 domains, we show that binding is mediated via the Src homology region 2 (SH2)-containing inositol phosphatase (SHIP) SH2 domain. SHIP also bound to a phosphopeptide derived from CD22, raising the possibility that SHIP contributes to negative signaling by this receptor as well as Fc gammaRIIB1. The association of SHIP with the ITIM phosphopeptide was activation independent, while coassociation with Shc was activation dependent. Furthermore, experiments with Fc gammaRIIB1-deficient B cells demonstrated a genetic requirement for expression of Fc gammaRIIB1 in the induction of SHIP phosphorylation and its interaction with Shc. Based on these results, we propose a model of negative signaling in which co-cross-linking of surface immunoglobulin and Fc gammaRIIB1 results in sequential tyrosine phosphorylation of the ITIM, recruitment and phosphorylation of p145SHIP, and subsequent binding of Shc.     

Nuclear accumulation of G-actin in isolated rat hepatocytes by adenine nucleotides

Distinct inositol and phosphatidylinositol polyphosphates 5-phosphatases have recently been cloned. Primers have been designed coding for highly conserved amino acid regions that are shared between sequences of 5-phosphatases. One of the PCR fragment referred to as 51 C, shows 99% identity to a previously reported sequence (INPPL-1) present in the database. We report here the identification of cDNAs for a new SH2-domain-containing protein showing homology to the inositol 5-phosphatase SHIP and therefore referred to as SHIP2. SHIP2 differs at both N- and C-terminal ends with the sequence of INPPL-1. The translated sequence of SHIP2 encodes a 1258 amino acid protein with a predicted molecular mass of 142 kDa. Particularly high levels of SHIP2 were found in human heart, skeletal muscle and placenta as shown by Northern blot analysis. SHIP2 was also expressed in dog thyroid cells in primary culture where the expression was enhanced in TSH and EGF-stimulated cells.     

Targeted disruption of SHIP leads to Steel factor-induced degranulation of mast cells

To investigate the role of the src homology 2 (SH2)-containing inositol 5' phosphatase (SHIP) in growth factor-mediated signalling, we compared Steel factor (SF)-induced events in bone marrow-derived mast cells (BMMCs) from SHIP-/- and SHIP+/+ littermates. We found SF alone stimulated massive degranulation from SHIP-/- but none from SHIP+/+ BMMCs. This SF-induced degranulation, which was not due to higher c-kit levels in SHIP-/- cells, correlated with higher intracellular calcium than that in SHIP+/+ cells and was dependent on the influx of extracellular calcium. Both this influx and subsequent degranulation were completely inhibited by PI-3-kinase inhibitors, indicating that SF-induced activation of PI-3-kinase was upstream of extracellular calcium entry. A comparison of phosphatidylinositol-3,4,5-trisphosphate (PIP3) levels following SF stimulation of SHIP+/+ and SHIP-/- BMMCs suggested that SHIP restricted this entry by hydrolyzing PIP3. Although PI-3-kinase inhibitors blocked the release of intracellular calcium, implicating PIP3, and PLCgamma-2 was slightly more tyrosine phosphorylated in SHIP-/- cells, the increase in inositol-1,4,5-trisphosphate (IP3) and intracellular calcium levels were identical in SHIP-/- and SHIP+/+ BMMCs. These results suggest that SHIP prevents SF from triggering degranulation of normal BMMCs, and does so by hydrolyzing PIP3, which in turn limits extracellular calcium entry at a step after the release of intracellular calcium.     

The human SHIP gene is differentially expressed in cell lineages of the bone marrow and blood

The macrophage colony-stimulating factor receptor and several other hematopoietic growth factor receptors induce the tyrosine phosphorylation of a 145- to 150-kD protein in murine cells. We have previously cloned a cDNA for the murine 150-kD protein, SHIP, and found that it encodes a unique signaling intermediate that binds the SHC PTB domain through at least one tyrosine phosphorylated (NPXY) site in the carboxyl-terminal region. SHIP also contains several potential SH3 domain-binding sites, an SH2 domain for binding other tyrosine phosphorylated proteins, and an enzymatic activity that removes the phosphate from the 5 position of phosphatidylinositol 3,4,5-phosphate or from inositol 1,3,4,5-phosphate. SHIP has a negative effect on cell growth and therefore loss or modification may have profound effects on hematopoietic cell development. In this study, we have cloned a cDNA for human SHIP and examined mRNA and protein expression of SHIP and related species in bone marrow and blood cells. Flow cytometry indicates that at least 74% of immature CD34+ cells express SHIP cross-reacting protein species, whereas within the more mature population of CD33+ cells, only 10% of cells have similar expression. The majority of T cells react positively with the anti-SHIP antibodies, but significantly fewer B cells are positive. Immunoblotting detects up to seven different cross-reacting SHIP species, with peripheral blood mononuclear cells exhibiting primarily a 100-kD protein and a CD34+ acute myeloblastic leukemia expressing mainly 130-kD and 145-kD forms of SHIP. Overall, these results indicate that there is an enormous diversity in the size of SHIP or SHIP-related mRNA and protein species. Furthermore, the expression of these protein species changes according to both the developmental stage and differentiated lineage of the mature blood cell.