改性超细Al(OH)_3水悬浮液的稳定性

选用六偏磷酸钠对超细Al(OH)3 粉体进行湿法改性,利用红外光谱评价其改性效果.通过沉降量、沉降速率及透光率的测定,研究了分散剂、pH值、温度和搅拌速率对Al(OH)3水悬浮液体系的稳定性影响.结果表明,六偏磷酸钠湿法改性过的Al(OH)3 粉体亲水性增强,在288 K,pH值为11的条件下,控制搅拌速率为600 r/min,加入0.2%的Tween-20可制得分散性和稳定性俱佳的改性Al(OH)3水悬浮液体系.     

共沉淀法制备A1(OH)3-Y(OH)3/ZrB2复合粉体的热力学形成条件研究

由于ZrB2的独特晶体结构,使其兼有金属和陶瓷的许多优异的物理和化学性能,因此在许多领域得到广泛应用.本文利用共沉淀法制备Al(OH)3-Y(OH)3/ZrB2复合粉体,并研究其形成热力学条件.经过热力学计算并用实验验证得出:ZrB2悬浮液的pH值必须大于8.3,才符合Al3+与Y3+共沉淀所需热力学条件;当ZrB2悬浮液的pH值为9时,Al (OH)3-Y(OH)3/ZrB2复合粉体的壳-核结构最好.在溶液浓度较低的情况下,可以获得具有理想壳-核结构的Al (OH)3-Y(OH)3/ZrB2复合粉体,即c(Al3+) =0.017mol/L,c( Y3+) =0.010mol/L,分别接近于Al( NO3)3和Y(NO3)3浓度的热力学条件计算拟定值,即:0.012 60mol/L和0.007 56mol/L.     

共沉淀法制备Al（OH）3-Y（OH）3/ZrB2复合粉体的热力学形成条件研究

由于ZrB2的独特晶体结构,使其兼有金属和陶瓷的许多优异的物理和化学性能,因此在许多领域得到广泛应用。本文利用共沉淀法制备A1(OH)3-Y(OH)3/ZrB2复合粉体,并研究其形成热力学条件。经过热力学计算并用实验验证得出:ZrB2悬浮液的pH值必须大于8.3,才符合Al3+与Y3+共沉淀所需热力学条件;当ZrB2悬浮液的pH值为9时,A1(OH)3-Y(OH)3/ZrB2复合粉体的壳-核结构最好。在溶液浓度较低的情况下,可以获得具有理想壳-核结构的A1(OH)3-Y(OH)3/ZrB2复合粉体,即c(Al3+)=0.017mol/L,c(Y3+)=0.010mol/L,分别接近于Al(NO3)3和Y(NO3)3浓度的热力学条件计算拟定值,即:0.012 60mol/L和0.007 56mol/L。     

Fe(OH)3吸附法从高钨钼酸钠溶液中分离钨钼的研究

研究了用Fe（OH）3吸附法从高含钨的钼酸钠溶液中分离钨的可能性及技术条件。试验表明，在pH=7．0和Fe（OH）3用量为WO4^2-量2～4倍的条件下，每次吸附能分离70％～80％的钨。对WO3／MO=0．445的物料而言，经一次吸附可使WO3/Mo降为0．17～0．18。试验中开发了一种以HCl＋NH4Cl作中和剂将Na2MoO4溶液中和的新方法，采用这种方法可显著提高回收率及分离效果。     

共沉淀法制备稀土石榴石Ln3Al5O12(Ln=Y, Ce, Yb)

以Y2O3、Yb2O3、Al(NO3)3.9H2O和Ce(NO3)3.6H2O为原料,NH4HCO3、NH3.H2O做复合沉淀剂,用共沉淀法制备纳米稀土石榴石Ln3Al5O12(LnAG,Ln=Y,Ce,Yb)粉体。用TG/DTA、XRD、SEM、TEM等手段对LnAG前驱体及煅烧后的粉体进行表征。结果表明,用上述方法在1 000℃煅烧3h可得到分散性好、形状规则且粒径为50nm左右的Y3Al5O12、Yb3Al5O12、Y2.9Ce0.1Al5O12石榴石粉体,但不能得到Ce3Al5O12石榴石,合成石榴石粉体的最佳煅烧温度为1 050℃以上。     

(Sm2O3)0.04(Gd2O3)0.06掺杂CeO2纳米粉体的制备与表征

以Sm2O3、Gd2O3与Ce2(CO3)3·nH2O为原料,采用改进的沉淀法制备了二元稀土(Sm2O3)0.04 (Gd2O3)0.06掺杂CeO2纳米粉体.测定了pH值对0.80Ce(OH)4·0.08Sm(OH)3·0.12Gd(OH)3水溶胶体系Zeta电位的影响.pH值约为7.0时,体系的Zeta电位为0,即体系的等电点(IEP)为7.0.pH值为10.0时,Zeta电位达到最大值-18.5mV,说明此时该体系的稳定性最好.DTA/TG热分析表明,0.80Ce(OH)4·0.08Sm(OH)3·0.12Gd(OH)3粉体的热分解温度约为232℃.由粉末XRD分析可知,经750℃焙烧的二元稀土掺杂CeO2粉末为立方萤石结构,说明Sm2O3与Gd2O3已完全固溶到CeO2中,形成了CeO2基固溶体.由TEM照片可以看出,粉末具有良好的分散性,呈软团聚状态,粒径在5nm～10nm之间.经BET测试计算的平均颗粒尺寸为11nm,与TEM结果是一致的.     

添加剂对均匀沉淀法制备Al(OH)3微粉形貌的影响

利用均匀沉淀法从AlCl3-尿素体系制备Al（OH）3微粉，研究了不同的添加剂对粉末形貌的影响，并用扫描电镜分析了所制得的粉末形貌。结果表明：在运用均匀沉淀法AlCl3-尿素体系制备Al（OH）。微粉过程中，添加剂对其形貌的影响较大，且不同添加剂对粉末的形貌有着不同的影响结果。加入PVP和NaH2PO4，粉末仍未产生规则形貌；加入PVA后，颗粒长成片状结构；添加SDS，颗粒较分散，但形貌不规整；加入物质X则得到了规则的球形颗粒。     

Preparation and Electrorheological Property of Y4O（OH）9（NO3）-NH4NO3 Materials

The new electrorheological (ER) material, a particle material composed of Y4O(OH)9(NO3) and NH4NO3, was obtained.They display better ER performance.The shear stress of the suspension of Y4O(OH)9(NO3)(NH4NO3)2.8 material in dimethyl silicone oil reaches 1469 Pa at an electric field strength (E) of 4.2 kV·mm-1 and the shear rate (γ) of 150 s-1.The relative shear stress, τE/τ0 (τE and τ0 are the shear stresses at E=4.2 and 0 kV·mm-1, respectively), is up to 29, which is 19 times that of pure Y2O3 material.The dielectric and conductive property of the materials play important roles in the modification of the ER effect of the particle materials.The researches on these new ER materials are very useful for obtaining a better understanding on the mechanism of the ER effect and finding an ideal ER material.     

Fe2O3粉末表面非均匀成核法包覆

为解决氧化铁红在高温下呈现不稳定性的问题, 采用非均匀成核法使Si（OH）4和Al（OH）3均匀包覆在氧化铁红粉末颗粒表面, 用X射线衍射仪、透射电镜、 Zeta电位测定仪对包覆前后的Fe2O3粉末颗粒进行分析. 结果表明, 通过非均匀成核法可以制备出被SiO2和Al2O3包覆的Fe2O3复合粒子, 其技术的关键是如何控制反应溶液pH值和涂层物质沉淀的反应浓度, 以保持被覆颗粒稳定的悬浮特性.     

共沉淀法制备Al/Cr_2O_3复合粒子及其性能研究

采用共沉淀法将Cr2O3复合于片状金属铝粉表面获得了包覆效果好的Al/Cr2O3复合粒子。为了保证复合粒子的红外隐身性能,对前躯体粒子Al/Cr(OH)3进行了TG-DSC测试,确定了对前躯体的热处理温度;同时借助于XRD,SEM测试对制得的Al/Cr2O3粉末的相组成和形貌进行了表征,此外,将Al/Cr2O3粉末制成红外隐身涂层进行红外辐射率性能测试。结果表明,当铝粉含量为50%(质量分数)时制得的Al/Cr2O3复合粒子包覆较为完整,红外辐射率值最低为0.77。Cr2O3对片状Al粉的包覆在降低红外辐射率的同时不仅避免了Al粉的"显形"和氧化,其本身的绿色还可以起到可见光隐身的效果,在林地的迷彩隐身中具有重要的应用价值。     

氢氧化镧和氢氧化钕微粉的制备

采用化学共沉淀法制备La(OH)3和Nd(OH)3微粉,研究了反应物浓度、氨水浓度、滴定速度以及加入分散剂对制备La(OH)3微粉和Nd(OH)3微粉粒度的影响,初步确定了制备D50≤1μm的La(OH)3微粉和Nd(OH)3微粉的最佳工艺条件。     

Hydrothermal synthesis of Y(OH)3, Y(OH)3:Eu3+ nanotubes and the photoluminescence of Y(OH)3:Eu3+,Y2O3:Eu3+

The phase and morphology transformation during the hydrothermal treating process of Y2O3 was evaluated with X-ray diffcrcnce (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size and specific surface area determination.The results showed that the cubic Y2O3 did not transfer into hexagonal Y(OH)3 in pure water. Therefore, pure hexagonal Y(OH)3 with nanotube and microrod morphologies were obtained by hydrothermal treating Y2O3 at 150℃ for 12 h in 15 ml of 2 mol/L NaOH solution with and with-out PVA or PEG It was suggested that the characteristic preferential growth of Y(OH)3 was attributed to the structure anisotropy of hexahedron Y(OH)3. The addition of PVA or PEG could promote the forming process of nanotubes by selective adsorption on different crystal planes,which altered the growth rate along different directions and resulted in the diffusion limit of constructing ions in the center top of rods. Finally,Y(OH)3:Eu and Y2O3:Eu nanotubes were also synthesized by using this method, and their photoluminescence properties were evaluated.     

离子膜电解法制备La(OH)3

利用阴离子交换膜电解方法制备了La(OH)3。研究了电极材料、电流密度、反应介质对La(OH)3的影响。使用不锈钢材料作阴极,在电流密度低于300 A.m-2时,La(OH)3质量随电解时间线性增大。较佳工艺条件为:电流密度300 A.m-2,LaCl3浓度为0.2 mol.L-1,添加剂浓度为15%。循环伏安曲线表明,电解过程中不锈钢表面氧化膜和H 的还原均有一个电流阶跃,两个阶跃间有一个相对平缓的电流区域。相同电压时,无添加剂的0.2 mol.L-1LaCl3溶液电流最大,含15%添加剂时的电流下降,0.6 mol.L-1NaCl空白溶液的电流最小。La(OH)3的生成使析氢电位正移。     

Anti-tumor effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in seborrheic keratosis

1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is a drug with potent antiproliferative action on keratinocytes that have nuclear receptors for 1,25(OH)2D3. We investigated the effects of 1,25(OH)2D3 on widespread seborrheic keratoses in 51 patients with these tumors. The data indicated that resolution of these tumors was dependent on both tumor size and dose of 1,25(OH)2D3. Among 15 patients treated with a high dose (0.5 microgram/d) of oral 1,25(OH)2D3, the lesions of widespread seborrheic keratoses changed from brown-black papules to brownish papules with erythema and/or crust as early as 2 wk after the start of treatment. The tumors finally developed into an atrophic scar or brownish pigmented macule. Histologically, vacuolation of the spinous cells, vesicle formation, and liquefaction degeneration of the basaloid cells were observed. Numerous lymphocytes had infiltrated in the papillary dermis. Among 36 patients treated with a low dose (0.25 microgram/d) of 1,25(OH)2D3, brownish papules became pale to normal in color and reduced in size, without erythematous change. Histologically, acanthosis of the epidermis was reduced, but degenerative change of the tumor cells was not observed. These data suggest that oral therapy of 1,25(OH)2D3 is an acceptable method well suited to the removal of seborrheic keratoses, especially those that are predominantly small tumors.     

循环流化床氢氧化铝焙烧系统的设计软件平台开发

针对循环流化床氢氧化铝焙烧系统,基于Delphi对整个焙烧系统的物料平衡、能量平衡和尺寸设计进行了软件平台的开发工作,为设计人员提供了一个方便、快捷、清晰的计算机辅助设计平台,为焙烧炉的设计和开发工作提供了实用的可视化手段。     

1,25(OH)2D3-modulated calcium induced keratinocyte differentiation

The purpose of this study was to provide optometrists with suggested base curves and powers for initial lens choice based on the infant's age. A retrospective chart review of 16 congenital cataract patients fitted at U.C. Davis Eye Clinic between July 1987 and May 1993 was performed. Patients with associated ocular pathologies were excluded. All patients were fitted with a Bausch & Lomb Silsoft lens, a Silicone Elastomer, set at a 3.00 D myopic posture, which was decreased with the child's increasing age and activity. This study provides a graphical approach to pediatric aphakic silicone elastomer contact lens fitting. Best-fit regression lines for both graphs have an r squared value better than 0.9. Optometrists will now be able to reference the Base Curve vs. Age and Power vs. Age graphs to determine the initial lens choice when keratometry is unachievable. Furthermore, the data suggest a need for an increased range of powers provided by the Silicone elastomer lens in order to approximate normal visual development.