用呋喃树脂砂造型浇注 HCF-82钢锭模的试验

一、前言宝钢钢锭模车间引进了新日铁用高呋喃树脂砂制造钢锭模的工艺,而当时国内还没有相应的糠醇含量达到90%的高呋喃尿醛树脂(以下简称高呋喃树脂)。为了在宝钢投产以后、使高呋喃树脂的供应能基于国内,在C 阶段谈判结束以后,我们就着手组织并委托有关科研单位,一起进行高呋喃树脂的研制和试验。经过几年努力,初步研制出一种高呋喃树脂,模索     

“汇波牌”XLZ型呋喃树脂的发展及应用

概述了呋喃树脂的最新发展,介绍了“汇波牌”XLZ呋喃树脂的性能,用途,使用方法及应用。     

呋喃树脂砂生产铸铁件过程控制

呋喃树脂砂铸造虽是成熟的工艺,但生产中铸件的缺陷频频出现,因此本文以铸造流程为脉络,讲述了呋喃树脂砂生产铸铁件的过程控制,希望对铸造缺陷控制具有指导意义。     

焦化厂YJ-Ⅱ型呋喃树脂 耐酸石材 防腐蚀地坪工艺探讨

本文结合我公司焦化厂防腐蚀地坪实际情况，探讨了YJ-Ⅱ型呋喃树脂、耐酸石材防腐蚀地坪的制作工艺。     

呋喃树脂混凝土铜电解槽

文章叙述了呋喃树脂混凝土铜电解槽的制做工艺、使用材料、主要技术性能,以及该厂几年来在生产中应用的效果。     

呋喃树脂电解槽在铜电解生产中的应用

文章介绍了呋喃树脂电解槽在铜电解生产过程中的试用与生产实践对使用呋喃电解槽的优点及其经济效益进行了分析与评估。     

热风炉炉篦子铸造工艺设计及生产

形状各异密布梅花孔的热风炉炉篦子，采用自硬呋喃树脂砂作型芯材料，造型采用坭芯组装的工艺方法，保证了孔距精度和炉篦子质量，解决了铸造生产中的难题。     

组芯造型铸造工艺在电机铸件上的应用

介绍了二种电机主要铸件的结构特点，从工艺角度分析了制造过程中的难点，采用呋喃树脂砂制芯并进行组芯造型的铸造工艺，获得了外观质量好，尺寸精度高的铸件。     

铜电解槽FRP衬里的使用与维修

铜电解槽采用197不饱和树脂FRP内衬,较铅皮和呋喃树脂FRP内衬的使用寿命延长,但施工条件要求较严格,周期长。现正探索—种无衬里耐腐蚀电解槽。     

树脂砂造型生产钢锭模的研究与应用

本文论述了树脂砂生产线的概况及树脂砂工艺的技术特性,对呋喃树脂砂与碱性酚醛树脂砂的性能进行了对比,确定了碱性酚醛树脂的优势,解决了北方气候条件下树脂砂工艺的正常运行问题,并对碱性酚醛树脂砂在实际生产中的应用进行了研究.     

Effect of praseodymium on catalytic graphitization of furan resin carbon

We introduced a new catalyst,rare earth element praseodymium,for the catalytic graphitization of furan resin carbon.The extent of graphitization of the furan resin carbon was examined by X-ray diffraction and Raman spectroscopy.The morphology of furan resin carbon was characterized by scanning electron microscopy.The effects of the praseodymium content and the heat-treatment temperature on the catalytic graphitization of furan resin carbon were also investigated.The results indicated that the praseodymium c...     

稀土对呋喃树脂-柔性石墨复合材料性能的影响

本文研究了不同种类稀土对呋喃树脂－柔性石墨复合材料性能的影响。结果表明，复合材料的肖氏硬度、电阻率、压缩率及回弹率明显地依赖于稀土种类与用量，在本实验条件下加入０．９％（ｗｔ）ＣｅＯ２时，材料的综合性能最佳；而体积密度基本不受ＣｅＯ２用量影响。结合表面形貌ＳＥＭ分析，从稀土活性中心对树脂与石墨之间界面粘结力的影响以及稀土对树脂固化过程的助催化两方面初步探讨了稀土的作用机理。     

解决钠离子交换树脂"中毒"问题的方案探讨

本文介绍了东北轻合金有限责任公司锅炉用软化水处理工艺及钠离子交换树脂“中毒”类型和解决的办法。     

The predictive value of thyroid "test profile" in habitual abortion

A characteristic thyroid test profile is observed in pregnancy; it consists of an elevated serum thyroxine (T4I), thyroxine binding globulin (TBG) and electrophoretic index (EI) with lowered triiodothyronine resin uptake (T3U), the free thyroxine index (FTI) remaining in the normal range. An investigation was made of progressive changes in these parameters in 70 normal pregnant women, 34 pregnant women with a past history of habitual abortion who carried to term, seven habitual aborters who miscarried again, and 49 women at the time of spontaneous miscarriage. The results indicated that normal women reached a typical pregnancy thyroid test profile at seven to eight weeks' gestation while habitual aborters carrying a pregnancy to term reached it at 14 to 15 weeks and almost all patients who miscarried never reached it at all. In addition, four women who had aborted previously and were treated with thyroxine throughout six pregnancies, developed a normal "thyroid profile" and carried their pregnancy to term. The significance of the "predictive value" of the test profile is discussed.     

Rubral tremor associated with cavernous angioma of the midbrain

The insecticidal activity of five alkylfurans against the generalist insect herbivore beet armyworm, Spodoptera exigua, was examined. Two naturally occurring compounds, the avocadofurans 2-(pentadecyl)furan (1) and 2-(heptadecyl)furan (2), previously isolated from specialized avocado idioblast oil cells, and three homologues, 2-(tetradecyl)furan (3), 2-(hexadecyl)furan (4), and 2-(octadecyl)furan (5), were synthesized. Bioassays of alkylfurans 1-5 using a 9-day diet-incorporation initiated with neonates showed that all alkylfurans tested significantly increased S. exigua larval mortality and reduced larval weights, with maximal biological activity detected among the naturally occurring alkylfurans 1 and 2.     

Child psychiatry perspectives. After the "civilized" divorce

The sorption of bile acids, bilirubin, bilirubin glucuronates and cholesterol on ion-exchange resin is described. After some successful attempts of sorption of these substances from human and animal bile in vitro, this exchanger has been used in human therapy. Positive results obtained showed the usefulness of the method. The purpose of the experiments was to study the usefulness of ion-exchangers for sorption of bile components of bile acids, bilirubin, bilirubin glucuronates and cholesterol. First sorption was carried out on human and animal bile, on Zerolit-FS-ip, in cycles (OH-) and (Cl-), by passing through glass columns downwards and some of them by mixing the bile with ion-exchange resin. Zerolit FS-ip is an organic sorbent, a scavenger, a strongly basic macroporous, anion exchanger. Positive results of these sorptions indicated the possibility of using this method in therapy of disturbed lipid conditions.     

Characterization of amino acid and glutathione adducts of cis-2-butene-1,4-dial, a reactive metabolite of furan

Metabolic activation of the hepatocarcinogen furan yields metabolites that react covalently with proteins. cis-2-Butene-1,4-dial is a microsomal metabolite of furan. This reactive aldehyde is thought to be the toxic metabolite that is responsible for the carcinogenic activity of furan. In order to characterize the chemistry by which this unsaturated dialdehyde could alkylate proteins, the products formed upon reaction of cis-2-butene-1,4-dial with model nucleophiles in pH 7.4 buffer were investigated. N(alpha)-Acetyl-L-lysine (AcLys) reacts with cis-2-butene-1,4-dial to form N-substituted pyrrolin-2-one adducts. N-Acetyl-L-cysteine (AcCys) reacts rapidly with cis-2-butene-1,4-dial to form multiple uncharacterized products. The inclusion of AcLys in this reaction mixture yielded an N-substituted 3-(S-acetylcysteinyl)pyrrole adduct which links the two amino acid residues. Related compounds were isolated when cis-2-butene-1,4-dial and glutathione (GSH) were combined. In this case, cis-2-butene-1,4-dial cross-linked two molecules of GSH resulting in either cyclic or acyclic adducts depending on the relative GSH concentration. Incubation of furan with rat liver microsomes in the presence of [glycine-2-3H]GSH led to the formation of radioactive peaks that coeluted with synthetic standards for the bisgluthathione conjugates. These studies demonstrate that the reactive cis-2-butene-1,4-dial formed during the microsomal oxidation of furan reacts rapidly and completely with amino acid residues to form pyrrole and pyrrolin-2-one derivatives. Therefore, this metabolite is a likely candidate for the activated furan derivative that binds to proteins. The ease with which cis-2-butene-1,4-dial cross-links amino acids suggests that pyrrole-thiol cross-links may be involved in the toxicity observed following furan exposure.     

Scavenging activity of furan derivatives against hydroxyl radical generated by Fenton system

As the continuation of the work on the antioxidant properties of furan derivatives, we have studied hydroxyl radical (OH.) scavenging activity of dimethylfuran (DMF) and diphenylfuran (DPF), which are well-known as an effective scavenger of singlet oxygen, by an ESR spin trapping technique. The incubation mixture of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapping agent with FE2+ and H202 in 50% acetonitrile aqueous solution gave 1:2:2:1 line signals characteristic of DMPO-OH spin adduct. The additions of furan derivatives to the incubation mixture decreased the intensity of the DMPO-OH spin adduct signal in a dose-dependent manner. The activities of furan derivatives were in the order of DMF > DPF > furan. The decrease in the intensity of the signals was not due to the inhibition of OH. generating system itself and the destruction of the spin adduct by furan derivatives. By comparison with the common OH. scavengers, DMF and DPF were found to scavenge OH. more effectively than dimethylsulfoxide and mannitol. These results indicate that DMF and DPF can act as a OH. scavenger as well as a singlet oxygen scavenger.     

Mutagenic effect of photoactivated methoxylated derivatives of 2-nitronaphtho (2.1-b) furan on the yeast Saccharomyces cerevisiae

2-nitro 7-methoxy naphtho [2,1-b] furan (R 7000) and 2-nitro 8-methoxy naphtho [2,1-b] furan, which are highly mutagenic on the bacterium Salmonella typhimurium have little activity on the yeast Saccharomyces cerevisiae. Nevertheless, irradiation at 365 nm elicits a weak but significant increase of their mutagenic activity on this yeast.     

Fumonisin B1 in maize for food production imported in The Netherlands

STATEMENT OF PROBLEM: When compared with waxes and prefabricated components made of dental alloys, processing resins is difficult and often results in a less accurate fit. The exact linear dimension is hard to realize, as the materials required for a dental casting are adjusted to dental waxes, and usually there are no special processing instructions for these resins. PURPOSE: The surface structure of 16 residue-free burning resins was determined to find which could enlarge the range of application for waxes in the dental casting technique. MATERIAL AND METHODS: A total of 480 specimens (30 castings for each of 16 resins) were marked with an individually cut pyramid, which left an impression in the resin. This was distinctly visible in the metal after casting in "the lost form." The surfaces of these 480 specimens were measured in three dimensions with a positioning aid "before casting in resin" and "after casting in metal" by the Perthometer micrometer. All specimens were treated identically by the lost-wax process by using the rotation symmetry of the muffle. The differences in the surface data before casting in resin and after casting in metal characterize the quality of the particular resin. RESULTS: Surface roughness differed between the 16 resins in the range of micrometer. CONCLUSIONS: With the dental casting technique, it is recommended that some resins replace waxes or wax-resin compositions.