宁波绿茶氟含量的调查分析

氟作为对人体有益的微量元素,适量的氟摄人对人体有益,过量的氟摄人对人体有害。而茶树是一种聚氟作物,茶叶中的氟含量直接影响人体的健康。本文旨在调查研究分析宁波九大茶区的绿茶氟含量现状,意在让人们重视饮茶中氟摄人对人体健康所产生的影响,引导人们合理的选择健康饮品和科学的泡饮绿茶,从而让氟元素在人体里发挥其合理的功效。     

2003年2月份部分有机氟产品市场参考价格

产品名称规格型号产地价格 (元 /吨 )对氟苯甲醛国产 1 750 0 0对氟苯甲酸国产 1 30 0 0 0对氟苯甲酸乙酯 99%国产 2 0 0 0 0 0对氟苯乙酮 99%国产 1 30 0 0 0对氟氯苄国产 1 4 0 0 0 0分散聚四氟乙烯树脂国产 80 0 0 0氟表面活性剂ＳＦ - 4 0 2国产 1 30 0 0 0氟润滑脂ＳＦ -     

对氟离子呈现状态和比色响应的有机凝胶的研究进展

氟离子刺激响应的有机凝胶因子通过氢键识别或复合氟离子,使紫外吸收波长红移而发生颜色变化,实现比色响应;同时破坏凝胶形成的主要驱动力,诱导凝胶-溶胶转变,实现状态响应。能够响应外界氟离子刺激的有机凝胶在氟离子检测方面表现出明显的优势,具有方便快捷的肉眼检测效果,并且可以实现氟离子对准固体的检测,因此,具有氟离子刺激响应性的小分子有机凝胶受到人们越来越多的关注。文献报道较多的氟离子响应有机凝胶只能对氟离子刺激呈现状态响应,即氟离子加入能够诱导凝胶-溶胶转变,却不能诱导体系颜色变化;或者只能对氟离子刺激呈现比色响应,即氟离子加入能够诱导体系颜色变化,却不能诱导凝胶-溶胶转变。而对氟离子具有双重响应性的有机凝胶在氟离子探测方面具有更明显的优势,可以同时表现出肉眼可见的状态响应(凝胶-溶胶)和比色响应(颜色变化)。目前为止,对氟离子具有双重响应性的有机凝胶已经有一些报道。研究较多的是氢键型有机凝胶,凝胶因子中含有酰胺、酰腙、脲、酰肼等官能团,分子间氢键相互作用是凝胶形成的主要驱动力。由于氟离子有很强的电负性,能够与凝胶因子上的氢质子复合或发生去质子化,从而导致凝胶的破坏或颜色变化。因此,氟离子的响应机理基本上都是氢键相互作用和去质子化过程。但是凝胶因子与氟离子具体的响应过程千差万别,不仅与凝胶因子提供的氢键类型有直接关系,还与凝胶因子中的共轭基团、取代基性质和位置等有关。因此有必要对氟离子响应有机凝胶进行系统总结。基于此,结合本课题组近期对氟离子响应有机凝胶的研究结果,对近年来文献报道的有关氟离子刺激响应的有机凝胶体系,重点是近年来文献报道的对氟离子同时表现出肉眼可见的状态和比色响应的有机凝胶体系进行综述,以期为新型氟离子响应有机凝胶体系的分子设计提供一些参考。     

有机氟改性丙烯酸树脂的合成及研究

使用不同的有机氟单体对丙烯酸树脂进行改性,合成了具有低表面能性质的有机氟改性丙烯酸树脂;对树脂进行了红外和分子量检测,并测试了涂膜的附着力、抗冲击力、接触角等各项性能;研究了不同的氟单体种类、氟单体用量以及合成工艺对树脂性能的影响。结果表明,氟单体对丙烯酸树脂进行低表面能改性效果明显,其中含有叔碳原子和甲基结构,分子中含有12个F的G04单体效果最为理想;采用滴加氟单体工艺能够显著增大树脂的接触角;当氟单体G04用量在16.7%时,树脂与水的接触角最大可达104.5°。     

氟树脂对聚偏氟乙烯膜疏水性的影响

采用N,N-二甲基甲酰胺(DMF)为溶剂,以氟树脂为疏水助剂,制备聚偏氟乙烯(PVDF)膜.采用不同偶联剂对疏水助剂氟树脂进行改性,研究了改性氟树脂对PVDF膜疏水性的影响.研究结果表明:添加疏水助剂氟树脂可改善PVDF膜的疏水性.当经偶联刺G502改性的氟树脂添加量为10%时,PVDF膜与水的静态接触角达到120°.通过集灰实验表明添加改性氟树脂的PVDF膜具有较好的疏水性.     

室温固化型有机氟硅防污涂膜的制备及性能研究

使用氟硅氧烷交联剂,与基料羟基聚二甲基硅氧烷(PDMS)在二月桂酸二丁基锡的催化下室温交联固化制备了有机氟硅防污涂膜。对该涂膜表面氟含量、表面形貌、与水接触角等表面性能进行了测试,并通过抑藻实验测试了涂膜的防污性能。结果表明:氟硅氧烷交联剂对有机硅涂膜的性能影响效果较为显著,当氟硅氧烷交联剂用量为11.60%时,有机氟硅涂膜表面氟含量达到6.87%,接触角达到140.92°。抑藻性能测试中发现,当氟硅氧烷交联剂用量为11.60%时,与有机硅涂膜相比,有机氟硅涂膜对颗石藻的吸附量减少了86.67%,防污性能得到大幅度提高。     

疏水耐油氟硅橡胶的制备及性能

以1,3,5-三氟丙基-1,3,5-三甲基环三硅氧烷、四甲基四乙烯基环四硅氧烷为原料,四甲基二乙烯基二硅氧烷为封端剂,自制催化剂,制得性能优异的氟硅橡胶,以此生胶为基胶,制得氟硅混炼橡胶,讨论了合成氟硅橡胶的最佳工艺,分析了氟硅橡胶的疏水性、耐油性和力学性能。结果表明:氟硅橡胶生胶合成最佳反应温度110℃,反应时间60min,氟硅橡胶涂覆于玻璃表面对水的静态接触角可以达到137.49°,疏水效果良好,氟硅混炼橡胶具有很好的耐热稳定性、耐油性和优异的力学性能。     

四月份部分有机氟产品市场参考价格

产品名称规格型号产地价格 (元 /吨 )2 -氟 -4 -溴苄基溴≥ 99%国产 1 0 0 0 0 0 02 -氟 -4 -溴甲苯≥ 99%国产 90 0 0 0 03 ,4 -二氯三氟甲基苯 无色透明液体 99% 国产面议3 ,5-二硝基 -4 -　氯三氟甲苯 淡黄色晶体国产面议3 ,5-二硝基三氟甲苯≥ 99%国产 4 50 0 0 03 ,5-双三氟甲基　苯胺淡黄色液体 99% 国产面议3 -氨基 -4 -　氟三氟甲苯 ≥ 99%国产 650 0 05-氯 -2 -氨基　三氟甲基苯淡黄色透明液体 98 5% 国产面议氨基三氟甲苯≥ 98%国产 63 0 0 0八氟环丁烷国产面议对氟苯胺 无色透明液体 99% 国产面议对氟苯酚白色结晶 99%国产面议对…     

镧、铈改性介孔氧化铝对氟离子的吸附

以La、Ce为改性物负载至其他载体表面作为高效除氟吸附剂已经受到广泛的关注。但是将La和Ce负载到介孔氧化铝(MA)却少见报道。本研究制备了La和Ce改性介孔氧化铝并将其用于氟的去除。采用N2吸脱附等温线、X射线衍射(XRD)、傅里叶红外光谱(FTIR)对该吸附剂的结构性质进行了表征。同时,考察了吸附剂接触时间、初始浓度和溶液pH等吸附条件对氟离子吸附效果的影响。结果表明,反应在150 min时达到吸附平衡,此时La/MA的氟去除率达92. 2%,吸附氟容量大小为La/MA Ce/MA MA;氟吸附量随初始浓度的增大而增大;在pH值为5～9时,除氟效果较好;吸附等温线方程均符合Langmuir等温吸附模型; La/MA的氟离子最大吸附容量为27. 9 mg/g;共存阴离子对氟吸附的影响程度为CO32- SO42- NO3- Cl-。最后比较了吸附前后的FTIR,可以看出La/MA对氟离子去除效果最佳。     

沉淀法制备氟羟基磷灰石的影响因素

采用沉淀法制备了纳米氟羟基磷灰石(FHA), 研究了合成温度、初始氟离子浓度和 pH 值对氟替代的影响. 用 X 射线衍射和红外光谱表征了FHA粉体的物相组成和晶体结构变化, 用透射电镜观察了FHA的形貌. 结果表明: 氟替代会导致晶格参数和键能的变化, 随着合成温度或原料中氟浓度的升高, FHA 晶粒尺寸和长径比增大; 相组成主要受pH值控制, 考虑到OH^–和F ^–对羟基空位的竞争, 高pH值不利于氟替代.     

冷库氟里昂制冷系统冷风机除霜模式的探讨

文章主要介绍冷库氟里昂制冷系统中冷风机的几种常见的除霜模式,深入分析、比较不同除霜模式的能耗,提倡氟里昂制冷系统的节能投入。     

Heat transfer coefficients for a vertical fluted-plate condenser with R113 and 114

Heat transfer coefficients were obtained for film condensation on four different vertical fluted plates. Freon 113 and Freon 114 were used as working fluids. The tests were carried out over a wide range of vapour velocities. Empirical correlations are proposed to predict the average condensation heat transfer coefficients on a vertical rectangular fluted surface, wavy fluted surface and triangular fluted surface, respectively.     

Reactions of UF<Subscript>6</Subscript> and HF with Ethanol

Qualitative studies were performed, and the feasibility of ethanol fluorination by its reactions with anhydrous HF and UF₆ was demonstrated. The reaction occurs at temperatures of up to 150°С via replacement of OH groups with probable formation of Freon 161 and substitution of СH groups with the most probable formation of Freon 152. The Freons were identified by IR spectroscopy. The solid reaction products mainly consist of intermediate uranium fluorides. The formation of uranyl fluoride is not proved unambiguously.     

Heat transfer coefficients for a vertical fluted-plate condenser with R113 and 114Coefficients de transfert de chaleur pour un condenseur à plaques rainurées verticales fonctionnant au R113 et au R114

Heat transfer coefficients were obtained for film condensation on four different vertical fluted plates. Freon 113 and Freon 114 were used as working fluids. The tests were carried out over a wide range of vapour velocities. Empirical correlations are proposed to predict the average condensation heat transfer coefficients on a vertical rectangular fluted surface, wavy fluted surface and triangular fluted surface, respectively.     

Thermal conductivity of gaseous CFCl3 (Freon 11) and CF2Cl2 (Freon 12) and their mixtures with N2 at 292K

Thermal conductivity of the gases CFCl₃ (Freon 11), CF₂Cl₂ (Freon 12), and their binary mixtures with nitrogen have been measured at 292 K. The results for the mixtures are compared with various theoretical models, which give the thermal conductivity as a function of concentration using properties of the pure components. From the experimental results, the mutual diffusion coefficients for the two systems are calculated.     

Effect of fluorine doping on the optical loss in MCVD fibers based on heavily doped germanosilicate glass

We have studied the size distribution of silica glass particles in the fabrication of heavily doped germanosilicate glass fiber preforms by modified chemical vapor deposition (MCVD) at different Freon 113 concentrations in the gas mixture. The addition of Freon 113 to the gas mixture is shown to reduce the particle size in the deposited core glass layer and the optical loss in the fiber. A mechanism is proposed which accounts for the effect of the initial particle size in the core glass layer on the anomalous scattering and total optical loss in heavily doped step- and graded-index fibers.     

氟利昂罐式集装箱的安全使用与维护

介绍了氟利昂罐式集装箱的基本结构,叙述了氟利昂罐式集装箱的装卸作业、安全操作要求、安全性保证、紧急事故处理、定期检查和日常维护保养等要点。     

Experimental Investigation into the Exergy Loss of a Ground Heat Pump and its Optimization Based on Approximation of Piecewise Linear Functions

Journal of Engineering Physics and Thermophysics - The authors have presented experimental data on determining the thermodynamic parameters of a ground heat pump operating on Freon R407c on whose...     

Environmental shear deformation zones and crazes in crosslinked polystyrene and poly(para-methylstyrene)

Thin films ( 1m) of polystyrene and poly (para-methylstyrene) were bonded to annealed copper grids and crosslinked using electron radiation to increase, the network strand density. At each separate films were strained in air and in Freon 113 until the critical strain, _c, for plastic deformation was reached. Transmission electron microscopy observations reveal that both sets of films undergo a transition from crazing to localized shear deformation zones (DZs) as is increased. The critical strains for both crazing and DZ formation are markedly decreased in Freon 113. The DZs formed in Freon 113 show abrupt changes in extension ratio,, at their interfaces while those formed in air show more diffuse changes in. A mechanism for environmental DZ formation is proposed in which the diffusion rate of Freon 113 into the DZ is strongly enhanced by the ongoing plastic deformation. This mechanism is suggested by Rutherford backscattering measurements of Freon 113 diffusion into PS which show that such diffusion in the absence of plastic deformation is much too slow to allow the observed rate of growth of the environmental DZs.     

天然工质碳氢化合物的研究现状和前景分析

本文介绍了碳氢类制冷剂的发展背景和现状,从低温和空调这两个领域,分别概述各个领域的最新研究成果,通过碳氢类制冷剂与传统氟利昂型制冷剂的物性相比较,归纳出碳氢化合物作为制冷剂的独特优势;且讲述了关于安全性的问题;最后瞻望碳氢类制冷剂的发展前景.