金属材料分析方法的选择和施行第四讲金属材料中钛的测定(续)

2.4　铝钛中间合金中钛的测定(此方法由上海材料研究化学分析研究室提供)测定范围:w(Ti)≥1%方法提要:试样0.5000g,置于500ml锥形瓶中,加入盐酸(1+1)20ml,作用缓慢时加热至试样全溶,滴加过氧化氢(ρ1.11g·ml-1)3～5滴,煮沸。如溶液不清,过滤至另个500ml锥形瓶中,用盐酸(5+95)洗涤沉淀及滤纸。如沉淀中有不溶性钛的化合物存在,须将沉淀及滤纸置于铂坩埚中灰化,用焦硫酸钾熔融,熔块用稀硫酸浸出后并入于主液中。加硫酸(ρ1.84g·ml-1)5ml,加热蒸发至冒硫酸烟,冷却,加盐酸(1+1)100ml,加热溶解盐类,加水至约150ml,加入碳酸氢钠2g和铝片2g,随即…     

金属材料分析方法的选择和施行——第四讲 金属材料中钛的测定（续）

(2)高纯铝(纯度99.99%)中痕量钛的测定(摘自上海材料研究所1964年研究报告)适用范围:高纯铝测定范围:w(Ti)0.001%～0.010%方法提要:①试样的溶解及钛的分离　称取试样1 000～2 000g,置于聚四氟乙烯烧杯中,按每克试样6g氢氧化钠的比例加入氢氧化钠后分次加入水10ml,待自发溶解反应缓慢时加热至试样溶解完全,加水稀释至约200ml,加入铁溶液(ρFe5mg·ml-1)4ml,充分搅拌,加热至沸并保温约30min,冷却,过滤,用10g·L-1氢氧化钠溶液洗涤烧杯及沉淀。弃去滤液。分次用热盐酸(1+3)20ml将沉淀从滤纸上溶解并接受于原烧杯中。必要时在稀盐酸中加…     

金属材料分析方法的选择和施行第四讲金属材料中钛的测定(续)

2 .3　锌汞剂还原硫酸高铁铵滴定法测定钢铁中钛(JISG12 2 3- 1986 )测定范围 :w(Ti)≥ 0 .0 5 %方法提要 :(1)试样溶液的制备 :按表 1所示称取试样并溶解制成试样溶液。溶样在 30 0ml烧杯中进行。表 1　称样量及试样的溶解Tab .1　Massofsampleanditsdissolution含钛范围w(Ti) %称样量(m/ g)溶样方法可溶于盐酸的试样难溶于盐酸的试样≥ 2≥ 0 .5～ <2≥ 0 .0 5～<0 .51.0 0 0 02 .0 0 0 05 .0 0 0 0　 1～ 2g试样加盐酸 ( 1+1) 3 0ml及硫酸 ( 1+4 ) 10ml加热溶解　 5 g试样加盐酸( 1+1) 80ml及硫酸 ( 1+4 ) 10ml,加热溶解　每克试样加…     

金属材料分析方法的选择和施行第五讲金属材料中钨的测定

2.1.2　GB 7731.1-1987 钨酸沉淀重量法测定钨铁中钨量适用范围:钨铁中钨的测定测定范围:钨量w(W)>65%方法提要:(1) 试样的溶解　称取通过 0.088 mm筛孔的试样1.000 0 g置于铂坩埚中,加入浓氢氟酸5 mL,滴加浓硝酸分解试样。加入硫酸(1+1) 15 mL,小心蒸发至冒浓三氧化硫白烟,冷却,加入浓盐酸10 mL及热水30 mL使可溶的盐类溶解。用紧密滤纸过滤,滤液接受于600 mL烧杯中,用盐酸(1+9)洗涤沉淀及滤纸。滴加适量氨水(1+1)将滤纸上的钨酸沉淀溶解,用 20 g·L-1 氯化铵溶液洗涤残渣及滤纸。以上的盐酸洗液、溶解钨酸的氨水及氯化铵洗液均与600 m…     

磷钼钒杂多酸光度法测定钒

磷钼钒杂多酸早已用于磷的光度分析,其它应用尚未见报道。本文提出利用磷钼钒杂多酸光度测定高速钢中常量的钒,共存元素中铬、钴的影响以试样空白扣除,钨的负干扰可采用经验系数补正,样中1％Si和1％Nb不干扰测定。方法简便、快速、准确。本文还提出了在一定条件下形成磷钼钒酸、磷钨钒酸和磷钨钼酸的经验规律。 1 试剂与仪器 钼酸铵溶液:53g·L~(-1) 盐磷混酸:1.19g·ml~(-1)盐酸+1.74g·ml~(-1)磷酸=3+2 钒标准溶液:0.900mg·ml~(-1)(里偏钒酸铵配制并以滴定法标定) 721型分光光度计 2 分析方法称取试样0.1000g于200ml锥形瓶中(同时称一份不含钒的钢样作试剂空白A_0),加盐磷混酸1.5ml,硫酸(1+1)8ml,加热溶解,滴加浓硝酸助溶,继续加热     

金属材料分析方法的选择和施行——第四讲 金属材料中钛的测定（续）

③显色及光度测定　将分取的两份试液分别置于100ml容量瓶中,各加硫酸(1+1)25.0ml,加水至约65ml,加入50g·L-1硫酸铜溶液2滴,20g·L-1抗坏血酸溶液(用时现配)2.0ml,摇匀,加入50g·L-1DAPM溶液(1mol·L-1盐酸)10 0ml,加水至标线,摇匀。放置30min,用1cm或3cm的吸收皿,以试剂空白作参比,在400nm波长处测得其吸光度。④工作曲线的制备钛量为0～0.050mg的工作曲线:于一组100ml容量瓶中,依次加入0.010mg·ml-1钛标准溶液0,0.50,1.00,1.50,3.00及5.00ml,各加入20mg·ml-1铝溶液(约1.3mol·L-1盐酸)25 0ml,以下操作同③。钛量为0～0.160mg的…     

金属材料分析方法的选择和施行——第四讲 金属材料中钛的测定（续）

(2)过氧化氢光度法测定铝合金钛含量(摘自美国ASTM标准E34-68,在之后修订的标准中钛的测定已改为二安替比林甲烷光度法)适用范围:铝合金测定范围:w(Ti)0.01%～0.50%方法提要:称取0.300～1.000g试样(估计含钛0.15～3.0mg),置于400ml烧杯中,分次加入200g·L-1氢氧化钠溶液30ml,待剧烈反应趋于平静时加入硫酸硝酸混合酸[硝酸(1+5)300ml与硫酸(1+1)700ml混合]50ml使溶液酸化,温热使盐类溶解并驱除黄烟,冷却,将溶液移入100ml容量瓶中,加水稀释至标线,摇匀。用紧质滤干过滤,弃去最初流出的几毫升滤液。保留滤液25ml作为参比溶液。在剩余的…     

合金钢中钼的快速分析

试样用酸溶解,并以硝酸氧化,使钼成为6价,在硫酸存在下,用抗坏血酸将钼还原成5价(同时铁也被还原)。5价钼与硫氰酸盐形成络合物进行光度测定,发色速度快,色泽稳定,操作简单,重现性好,分析结果准确可靠。 分析方法:称取试样50mg于100ml锥形瓶中,加高氯酸2ml,硝酸(1+1)8滴,加热溶解,继续加热蒸发     

光度法快速测定锰

钛铁合金含较多硅和微量碳。测定锰,以往在铂皿或聚四氟乙烯烧杯中,加硫酸和氢氟酸溶解,冒烟除去硅和氟。铂皿昂贵,并除碳不便。硫酸冒烟温度高,聚四氟乙烯烧杯底部易损坏,且传热较慢,制备试液需2h甚至更长时间。本文试验在玻璃烧杯中加硫酸溶解,于试样基本溶解硅酸尚未析出时,加入氢氟酸3滴,继续溶解冒烟。经两年实践,此法溶矿速度快,操作简便,结果准确。对烧杯腐蚀轻微。 1 分析方法 称取试样0.18于125ml三角烧杯中,加硫酸(1 4)10ml,加热溶解,待试样基本溶解,硅酸尚未析出时加入氢氟酸3～4滴,蒸发至4～5ml,趁热沿杯壁加硝酸2滴管,氧化碳化物,继续蒸发至冒三氧化硫白烟2～3min,冷却,加硝酸     

金属材料分析方法的选择和施行第三讲钢铁中钼的测定(续)

2 .11　钢铁中钼的原子吸收光谱测定法 (摘自ГОСТ12 35 4- 81)适用范围 :合金钢、高合金钢测定范围 :0 .0 1% 5 .0 0 %方法提要 :(a)试样溶解 :称取 0 .5 0 0 0g试样 ,置于 2 5 0ml烧杯中 ,加入盐酸 硝酸 (3+ 1)混合酸 30ml ,加热溶解 ,再加硫磷混合酸 (每升溶液中含浓硫酸 15 0ml及浓磷酸 15 0ml) 30ml,蒸发至冒硫酸烟 ,冷却 ,加水4 0ml,加热溶解盐类 ,冷却 ,移入 10 0ml容量瓶中 ,加水至刻度 ,摇匀。如溶液呈混浊 ,则用干滤纸过滤 ,弃去初始的滤液。(b)测定溶液的准备 :根据试样含钼量的高低从 (a)节的澄清滤液中分取部分试液 ,置于 …     

Generation and detection of levuglandins and isolevuglandins in vitro and in vivo

Levuglandins (LGs) and isolevuglandins (isoLGs), formed by rearrangement of endoperoxide intermediates generated through the cyclooxygenase and free radical induced oxidation of polyunsaturated fatty acids (PUFAs), are extraordinarily reactive, forming covalent adducts incorporating protein lysyl ε-amino groups. Because they accumulate, these adducts provide a dosimeter of oxidative injury. This review provides an updated and comprehensive overview of the generation of LG/isoLG in vitro and in vivo and the detection methods for the adducts of LG/isoLG and biological molecules in vivo.     

Enthalpies of solution of purine and adenine in water and in dimethylsulfoxide

Journal of Solution Chemistry - Enthalpies of solution of purine and adenine in water and in demethylsulfoxide were measured calorimetrically in the temperature range 25–40°C. ΔH s...     

Coassembly of Nanorods and Nanospheres in Suspensions and in Stratified Films

The entropically driven coassembly of nanorods (cellulose nanocrystals, CNCs) and nanospheres (dye‐labeled spherical latex nanoparticles, NPs) was studied in aqueous suspensions and in solid films. In mixed CNC‐latex suspensions, phase separation into an isotropic latex‐NP‐rich and a chiral nematic CNC‐rich phase took place; the latter contained a significant amount of latex NPs. Drying the mixed suspension resulted in CNC‐latex films with planar disordered layers of latex NPs, which alternated with chiral nematic CNC‐rich regions. In addition, fluorescent latex NPs were embedded in the chiral nematic domains. The stratified morphology of the films, together with a random distribution of latex NPs in the anisotropic phase, led to the films having close‐to‐uniform fluorescence, birefringence, and circular dichroism properties.     

Determination of diazepam and nordazepam in milk and plasma in the presence of oxazepam and temazepam

For studies on the excretion of drugs into milk a sensitive high-performance liquid chromatographic assay was developed to quantitate diazepam and nordazepam in the milk and plasma of humans and rabbits in the presence of their major metabolites, oxazepam and temazepam. Flurazepam was used as an internal standard. The assay involves extractions with diethyl ether and an additional acid clean-up step. Chromatographic separation was achieved by a LiChrospher 60 RP-select B (5 microns) column and KH2PO4- acetonitrile (69:31, v/v) adjusted to pH 2.80 as a mobile phase. The same extraction and chromatographic conditions were suited to both types of samples, milk and plasma. The limits of determination using ultraviolet detection at 241 nm was for diazepam 20 ng/ml and for nordazepam 15 ng/ml. The absolute recoveries of diazepam, nordazepam and flurazepam in human milk were 84, 86 and 92% and in human plasma 97, 89 and 94%, respectively. The within- and between-day accuracy and precision for diazepam and nordazepam in milk and plasma at all concentrations tested (20-1500 ng/ml) were better than 8%. The high fat content which occurs in rabbit milk presented no limitation for the extraction of lipophilic diazepam: the method was successfully used to monitor milk and plasma concentrations of diazepam and nordazepam in lactating New Zealand White rabbits during 26-h infusions of diazepam (1.4 mg/h).     

Comparison and correlation of in vitro, in vivo and in silico evaluations of alpha, beta and gamma cyclodextrin complexes of curcumin

In the present study investigated the effect of curcumin (CUR) alpha (α), beta (β) and gamma (γ) cyclodextrin (CD) complexes on its solubility and bioavailability. CUR the active principle of turmeric is a natural antioxidant agent with potent anti-inflammatory activity along with chemotherapeutic and chemopreventive properties. Poor solubility and poor oral bioavailability are the main reasons which preclude CUR use in therapy. Extent of complexation was β-CD complex (82 %) > γ-CD (71 %) > α-CD (65 %). Pulverization method resulted in significant enhancement of CUR (0.002 mg/ml) solubility with CUR α-CD complex (0.364 mg/ml) > CUR β-CD complex (0.186 mg/ml) > CUR γ-CD complex (0.068 mg/ml). Gibbs-free energy and in silico molecular docking studies favour formation of α-CD complex > β-CD complex > γ-CD complex. With reference to CUR, relative bioavailability of CUR α-CD, CUR β-CD and CUR γ-CD complexes were 460, 365 and 99 % respectively. CUR–CD complexes exhibited increased bioavailability with an increase in t_½, tmax, Cmax, AUC, Ka, and MRT; and a decrease in Ke, clearance and Vd values. AUC increase was CUR α-CD complex > CUR β-CD complex > CUR γ-CD complex. Significant difference (p < 0.05) was observed between CUR α-CD complex and CUR γ-CD complex by one-way ANOVA and Dunnett’s post hoc test for multiple comparison analysis. Correlation observed between in vitro, in vivo and in silico methods indicates potential of in silico and in vitro methods in CD selection.     

Homo- and hetero-complexes of exchangeable apolipoproteins in solution and in lipid-bound form

The self-association state of human plasma apolipoprotein E (apoE) in solution and in complexes with dimyristoylphosphatidylcholine (DMPC) varying in stoichiometry was studied in sub-micromolar concentration range by gel filtration, fluorescence anisotropy, fluorescence quenching and energy transfer measurements with apolipoprotein labeled with lysine-specific fluorescent dyes. Together, these results confirm the equilibrium scheme for various apoE structures in solution: oligomer (in aged preparations) <==> 'closed' tetramer <==> 'open' tetramer ('molten globule' state) <==> native or partially denatured monomer <==> fully denatured monomer. Within DMPC:apoE discoidal complex (125:1) the apolipoprotein association state seems to be intermediate between that in solution and in larger vesicular complex (1000:1); for both complexes, the degree of exposure of fluorescein chromophores into water phase decreased. Hetero-associates of apoA-I and apoC-III-1 in solution and in the complexes with DMPC appear to behave similarly to apoE. When extrapolated to native HDL particles, 'molten globule' state seems to be a structure responsible for the interaction of exchangeable apolipoproteins with phospholipid. For a first time, the location of various apolipoprotein molecules on disc periphery was confirmed. The lysine residue(s) seems to locate closely to reacting residue(s) within apolipoprotein molecules in associates, however, with different package constraints for discoidal versus vesicular complexes with phospholipid.     

Structure of dimethoxyamine in the crystalline and gaseous phases and in solution

Conclusions It has been established by the methods of x-ray diffraction analysis and electron diffraction analysis and measurements of the dipole moments and the birefringence that in the crystalline and gaseous phases, as well as in solution, N,N-dimethoxyamine has a gauche-gauche conformation, which is stipulated by a stabilizing nO-N-O* orbital interaction. The geometric parameters of the molecule have been determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2235–2242, October, 1986.     

Fluorimetric quantification of clodronate and alendronate in aqueous samples and in serum

The bisphosphonates clodronate and alendronate are drugs in the therapy of osteoporosis or Paget's disease. They are highly hydrophilic and therefore of low oral bioavailability. Determination methods for bisphosphonates are often laborious and expensive equipment is needed. The presented quantification method based on kinetic measurement of the fluorescence decrease of an Al³⁺-morin complex can be used to determine the bisphosphonate content in aqueous and plasma samples. The intra- and inter-assay accuracies were found to be within 98.8% and 102.3% of the target samples for clodronate and within 97.2% and 105.0% of the target samples for alendronate. The LOQ was defined as 15.6 ng/ml for clodronate and 62.5 ng/ml for alendronate. In serum samples, intra- and inter-assay accuracy was found to be within 99.0% and 101.6% of the target samples for clodronate and within 97.8% and 102.6% of the target samples for alendronate. In serum samples, the LOQ was defined as 1.55 mg/ml for clodronate and 0.39 mg/ml for alendronate. Though less sensitive in serum, the presented method could support research on the development of drug delivery systems in vitro and in vivo for the investigated and other structurally related bisphosphonates.