X射线荧光光谱法测定精炼合成渣中的CaO、Al_2O_3、MgO和SiO_2

采用铂金坩埚电热熔融的方法制取玻璃片试样,应用X荧光光谱仪测定精炼合成渣中的CaO、Al2O3、MgO和SiO2,分析方法快速、准确,与传统的化学分析方法相比,精确度与准确度都能满足要求.     

X荧光光谱法测定铁矿石中主、次量元素的研究

使用熔融玻璃片法将试样与熔剂按照一定配比在高温下进行熔融以消除矿物、颗粒效应的影响制成玻璃片，进行荧光扫描后进行理论系数校正和经验系数校正，工作曲线优化后进行样品的荧光定量分析。     

X射线荧光光谱分析熔融法制样的系统研究

对X射线荧光光谱(XRF)分析的熔融法制样进行了系统地总结。内容包括熔剂的选择、氧化剂的选择、硫化剂的选择、重吸收剂的选择、脱模剂的选择,给出了氧化物、碳酸盐、硫化物、铁合金、石墨材料、铜精矿等几种典型样品熔融制备玻璃片的方法。介绍了铂黄合金坩埚和铸模的保养,而且对制备硼酸盐熔融玻璃片遇到的问题及解决办法都做了详细的说明,此外,还对3种不同类型的熔融设备及其特点做了介绍。研究内容对X射线荧光光谱分析工作者的熔融制样操作有一定指导意义。     

熔融制样X-射线荧光光谱法测定硅铁合金主次元素含量

为了能够制备出适合荧光分析的玻璃片主要分三步进行。第一步无水四硼酸锂粉末在高温下熔融挂壁在铂金坩埚表面,第二步样品特殊预氧化阶段,第三步用预氧化完成后的样品制备出适合X射线荧光光谱分析的玻璃片,该方法能够快速准确分析硅铁中4种元素的含量,克服了铂金坩埚不能直接用来熔融硅铁合金的缺陷。     

钴内标法X荧光仪测定铁矿石中的全铁

选择合适的熔融试剂,使用熔融玻璃片法将试样与熔剂按照一定配比在高温下进行熔融,以消除矿物、粒度效应的影响,应用钴内标法对全铁进行分析。实践证明此方法可行,能够满足生产的需要。     

X射线荧光光谱法测定精炼合成渣中的CaO、A12O3、MgO和SiO2

采用铂金坩埚电热熔融的方法制取玻璃片试样，应用X荧光光谱仪测定精炼合成渣中的CaO、Al2O3、MgO和SiO2，分析方法快速、准确，与传统的化学分析方法相比，精确度与准确度都能满足要求。     

熔融制样-X射线荧光光谱法测定钛铁中钛硅锰磷铝

熔融制样-X射线荧光光谱法测定钛铁合金中化学成分,核心技术是合金试样氧化技术,以有效避免样品熔融过程中铂-金坩埚受到侵蚀。在石墨垫底的瓷坩埚内以专用助熔剂将钛铁样品氧化成钛铁熔球,以四硼酸锂与碳酸锂混合熔剂熔融制备成玻璃片,建立X射线荧光光谱法(XRF)测定钛铁中钛、硅、锰、磷、铝含量的方法。试验探讨了熔剂选择、助熔剂用量、氧化条件、稀释比、脱模剂、熔融时间等条件对玻璃片质量及检测结果的影响,确定了最佳氧化、熔融实验条件。熔融制得的玻璃片强度高、质地均匀、检测面光洁,满足XRF测定要求。使用有证标准物质建立校准曲线,钛、硅、锰、磷、铝校准曲线相关系数介于0.999 6～1.000 0之间,校准曲线相关性满足XRF要求。方法应用于钛铁合金样品检测,各元素测定结果的相对标准偏差(RSD)介于0.25%～6.5%之间;准确度实验表明,钛铁标准样品测定结果与认定值相符。实验方法解决了钛铁熔融制样过程腐蚀铂-金坩埚问题,实现了钛铁合金中钛、硅、锰、磷、铝含量的同时快速分析,能够满足钛铁合金质量控制及作为炼钢生产指导的日常检测需求。     

X射线荧光光谱法测定铁原料中K、Na、Pb、Zn微量元素

采用高频熔融制备玻璃片样品,用市售国家标样和自制标样绘制工作曲线,确定最佳试验参数,消除干扰因素,成功实现X射线荧光光谱法测定铁原料中K、Na、Pb、Zn等微量元素.该方法检出限低,灵敏度高,操作简单快速,尤其适用于进厂铁原料的批量检测.     

熔融制样-X射线荧光光谱法测定硅锰合金和锰铁合金中硅锰磷铁

熔融制样-X射线荧光光谱法测定铁合金化学成分,关键技术是样品预氧化,以有效避免铂金坩埚受到侵蚀。试验以专用氧化剂预处理硅锰合金和锰铁合金样品,以四硼酸锂-混合熔剂(m(Li₂B₄O₇)∶m(LiBO₂)=67∶33)为熔剂熔融制备玻璃片,建立X射线荧光光谱法(XRF)测定硅锰合金和锰铁合金中硅、锰、磷、铁含量的方法。以碳含量校正烧失量对检测结果的影响,进一步探讨了氧化剂加入量、稀释比、熔融温度、熔融时间等条件对硅锰合金和锰铁合金中锰、硅、磷、铁含量的影响,得出最佳熔融条件。熔融制得的玻璃片均匀、光洁,满足XRF测定要求。各元素测定结果的相对标准偏差(RSD,n=12)在0.25%~4.3%之间;测定结果与硅锰、锰铁标准物质认定值相符。     

熔融制样-X射线荧光光谱法测定硅钙钡合金中硅钙钡磷铝

为消除硅钙钡合金试样熔融制片时侵蚀铂-黄坩埚的难题,实验中硅钙钡样品以四硼酸锂-碳酸锂(m∶m=2∶1)为预氧化熔剂,在石墨垫底的瓷坩埚中高温熔融成熔球,再将熔球转到铂-黄坩埚中,再用四硼酸锂为熔剂熔融制成玻璃片,这样铂-黄坩埚在熔融制样过程中的腐蚀问题得到了有效解决,实现了熔融制样-X射线荧光光谱法(XRF)对硅钙钡合金中硅、钙、钡、磷、铝的测定。实验确定了最佳制样条件:0.2000g试样、2.0000g四硼酸锂、1.0000g碳酸锂在石墨垫底的瓷坩埚中,500℃灰化完全,900℃熔融15min,取出冷却;移入盛有3.0000g四硼酸锂的铂-黄坩埚中,加0.50mL 300g/L碘化钾脱模剂,在1150℃熔融15min,取出摇匀,再熔融15min,取出摇匀冷却,制得均匀玻璃片。实验方法选用具有适当梯度的硅钙钡合金标样和内控样绘制校准曲线,各待测元素校准曲线的相关系数r≥0.9997。精密度结果表明,各元素测定结果的相对标准偏差(RSD,n=10)在0.11%~5.9%;正确度结果表明,硅钙钡合金标样采用本法分析,其测定值与标准值相吻合。硅钙钡试样采用本法分析,其测定值与行业标准的分析值一致性较好,并进行了成对数据t检验,结果表明本法与行业标准分析方法无显著性差异,能满足日常生产检测要求。     

14-3-3 facilitates Ras-dependent Raf-1 activation in vitro and in vivo

14-3-3 proteins complex with many signaling molecules, including the Raf-1 kinase. However, the role of 14-3-3 in regulating Raf-1 activity is unclear. We show here that 14-3-3 is bound to Raf-1 in the cytosol but is totally displaced when Raf-1 is recruited to the plasma membrane by oncogenic mutant Ras, in vitro and in vivo. 14-3-3 is also displaced when Raf-1 is targeted to the plasma membrane. When serum-starved cells are stimulated with epidermal growth factor, some recruitment of 14-3-3 to the plasma membrane is evident, but 14-3-3 recruitment correlates with Raf-1 dissociation and inactivation, not with Raf-1 recruitment. In vivo, overexpression of 14-3-3 potentiates the specific activity of membrane-recruited Raf-1 without stably associating with the plasma membrane. In vitro, Raf-1 must be complexed with 14-3-3 for efficient recruitment and activation by oncogenic Ras. Recombinant 14-3-3 facilitates Raf-1 activation by membranes containing oncogenic Ras but reduces the amount of Raf-1 that associates with the membranes. These data demonstrate that the interaction of 14-3-3 with Raf-1 is permissive for recruitment and activation by Ras, that 14-3-3 is displaced upon membrane recruitment, and that 14-3-3 may recycle Raf-1 to the cytosol. A model that rationalizes many of the apparently discrepant observations on the role of 14-3-3 in Raf-1 activation is proposed.     

露天多金属矿山采空区的钻探分析与工程应用

由于盗采等历史原因,在大宝山矿由地采转露采过程中,露天多金属矿铜采场采空区给露天采矿作业造成很大安全隐患.技术人员逐渐摸索出地质钻与潜孔钻联合钻探、三维激光扫描空区定位、探采结合的采空区超前钻探安全管理模式.该模式无论对现有矿山规模的正常生产,还是后续铜硫大开发项目的基建工程和正式运营均能取得良好的经济效益和社会效益,可以促进大宝山多金属矿的危机转型,为同类危机矿山的转型提供了有益的经验.     

多膛炉生产普通氧化钼收尾控制的研究

为了系统规范地控制12层多膛炉生产普通氧化钼的收尾,本文通过分析各层硫含量及拍摄炉况图片,在确定将11层作为收尾层的基础上,对收尾状态判断及非正常收尾状态下的调节方法进行了研究。结果表明,在收尾正常的状态下,10层炉内气氛清晰,炉内侧料脊发红而外侧发暗红,物料粒度较大,颜色为灰黑色为主夹有灰黄色,下料口物料堆积面积小;在收尾偏早的状态下,10层炉内气氛清晰,料脊发暗,物料粒度较大,颜色以灰黄色为主夹有灰黑色,下料口物料堆积面积小,可通过调小10-12层观察口让收尾下移;在收尾偏晚的情况下,10层炉内气氛模糊,料脊发红,物料粒度较小,颜色为灰黑色,炉温会自然升高,下料口物料堆积面积大,可通过调大10—12层观察口让收尾上移。     

A dimeric 14-3-3 protein is an essential cofactor for Raf kinase activity

cRaf-1 is a mitogen-activated protein kinase that is the main effector recruited by GTP-bound Ras in order to activate the MAP kinase pathway. Inactive Raf is found in the cytosol in a complex with Hsp90, Hsp50 (Cdc37) and the 14-3-3 proteins. GTP-bound Ras binds Raf and is necessary but not sufficient for the stable activation of Raf that occurs in response to serum, epidermal growth factor, platelet-derived growth factor or insulin. These agents cause a two- to threefold increase in overall phosphorylation of Raf on serine/threonine residues, and treatment of cRaf-1 with protein (serine/threonine) phosphatases can deactivate it, at least partially. The role of 14-3-3 proteins in the regulation of Raf's kinase activity is uncertain and is investigated here. Active Raf can be almost completely deactivated in vitro by displacement of 14-3-3 using synthetic phosphopeptides. Deactivation can be substantially reversed by addition of purified recombinant bacterial 14-3-3; however, Raf must have been previously activated in vivo to be reactivated by 14-3-3 in vitro. The ability of 14-3-3 to support Raf activity is dependent on phosphorylation of serine residues on Raf and on the integrity of the 14-3-3 dimer; mutant monomeric forms of 14-3-3, although able to bind Raf in vivo, do not enable Raf to be activated in vivo or restore Raf activity after displacement of 14-3-3 in vitro. The 14-3-3 protein is not required to induce dimerization of Raf. We propose that dimeric 14-3-3 is needed both to maintain Raf in an inactive state in the absence of GTP-bound Ras and to stabilize an active conformation of Raf produced during activation in vivo.     

南钢DF钢夹杂物分析研究

对南钢转炉厂生产DF钢中的夹杂物进行了研究，结果表明现有工艺制度下吹氩精炼效果不明显，氩后钢中的夹杂物含量为865．78mg／kg；大于300μm的夹杂物，主要成分为Si—Al，或Si—Al—Mn；80～300μm夹杂物，主要成分为Si—Al-Mn，且Si较高，Mn较低；小于80μm的夹杂物，主要成分为Si—Al—Mn，并且含Mn较高：改变钢液脱氧制度及控制吹氩搅拌，可使氩后钢中及铸坯中的夹杂物含量分别降低到203．38mg/kg、59．8mg／kg。     

宣钢大方坯品种钢的连铸工艺优化

2007年底宣钢进行品种结构调整,将120t转炉-130tLF精炼炉-12流方坯连铸机生产线的6号连铸机转为生产200mm×285mm断面大方坯品种钢。宣钢炼钢厂为满足大方坯品种钢生产需要,对6号连铸机进行了设备改造及品种钢生产工艺优化,改进后大方坯品种钢的热顶锻合格率、低倍合格率达到99％以上,成材率大幅度提高。     

Chymotrypsin gene expression in rat peripheral organs

Cdc25, the dual-specificity phosphatase that dephosphorylates the Cdc2-cyclin B complex at mitosis, is highly regulated during the cell cycle. In Xenopus egg extracts, Cdc25 is associated with two isoforms of the 14-3-3 protein. Cdc25 is complexed primarily with 14-3-3epsilon and to a lesser extent with 14-3-3zeta. The association of these 14-3-3 proteins with Cdc25 varies dramatically during the cell cycle: binding is high during interphase but virtually absent at mitosis. Interaction with 14-3-3 is mediated by phosphorylation of Xenopus Cdc25 at Ser-287, which resides in a consensus 14-3-3 binding site. Recombinant Cdc25 with a point mutation at this residue (Cdc25-S287A) is incapable of binding to 14-3-3. Addition of the Cdc25-S287A mutant to Xenopus egg extracts accelerates mitosis and overrides checkpoint-mediated arrests of mitotic entry due to the presence of unreplicated and damaged DNA. These findings indicate that 14-3-3 proteins act as negative regulators of Cdc25 in controlling the G2-M transition.     

Oxidation kinetics of ilmenite concentrate by non-isothermal thermogravimetric analysis

The non-isothermal oxidation experiments of ilmenite concentrate were carried out at various heating rates under air atmosphere by thermogravimetry.The oxidation kinetic model function and kinetic parameters of apparent activation energy(Ea)were evaluated by Málek and Starink methods.The results show that under air atmosphere,the oxidation process of ilmenite concentrate is composed of three stages,and the chemical reaction(G(α)=1-(1-α)~2,whereαis the conversion degree)plays an important role in the whole oxidation process.At the first stage(α=0.05-0.30),the oxidation process is controlled gradually by secondary chemical reaction with increasing conversion degree.At the second stage(α=0.30-0.50),the oxidation process is completely controlled by the secondary chemical reaction(G(α)=1-(1-α)~2).At the third stage(α=0.50-0.95),the secondary chemical reaction weakens gradually with increasing conversion degree,and the oxidation process is controlled gradually by a variety of functions;the kinetic equations are G(α)=(1-α)~(-1)(β=10K·min~(-1),whereβis heating rate),G(α)=(1-α)~(-1/2)(β=15-20K·min~(-1)),and G(α)=(1-α)~(-2)(β=25K·min~(-1)),respectively.For the whole oxidation process,the activation energies follow a parabolic law with increasing conversion degree,and the average activation energy is 160.56kJ·mol~(-1).     

青城子铅锌矿田地质特征

辽东裂谷是大型陆间裂谷,是我国重要的有色金属及贵金属巨型成矿带,青城子矿田是辽东裂谷著名矿床。本文通过对青城子矿田的区域地质背景、控矿地质特征、矿床地质特征及同位素地质、成矿流体进行了全面的详细的研究与阐述,提出了青城子铅锌矿田的成因,海相火山喷流-厚积-变质-岩浆热液-叠加的再造型。     

离子交换分离富集极谱法连续测定金、铂、铱、铑、钌

研究了在同一份试液中极谱法连续测定Au、Pt、Ir、Rh、Ru的体系。首先在1mol/L的氢氧化钠溶液中,于原点电位-0.20V处扫描作Au的峰电流-质量浓度曲线;然后,改变溶液pH值,在0.75mol/L硫酸-1.5%氯化铵-1.5×10-3mol/L六次甲基四胺-0.003%硫酸肼体系中,于原点电位-0.78V处扫描作Pt、Ir、Rh的峰电流-质量浓度曲线;最后,加入2.25mol/L硫酸-4%氯化铵-2.5×10-4mol/L硫脲测定Ru。在选定的实验条件下得到令人满意的分析结果,线性范围分别为:0.1～1000μg/mL(Au);8×10-5～6.4×10-3μg/mL(Pt、Ir);1.6×10-5～1.28×10-3μg/mL(Rh);1.14×10-4～3.42×10-3μg/mL(Ru)。实际样品通过阴离子交换树脂分离富集后进行分析,回收率在93%～106%之间。