Fluorine in optics

Fluorine occupies an original and strategic position in modern optics. The F₂ excimer lasers are unrivaled sources of deep UV light for semiconductors, microphotolithography and micromachining which has brought on the development of single crystal calcium fluoride optics. Due to the weak polarisability of the fluoride ion, fluoride materials have low refractive index suitable for thin film antireflective coatings specially in IR optics. Transparent magnesium fluoride ceramics, prepared by fine grains hot pressing, are transparent in the mid IR where the transparency windows of the atmosphere are located. They are used as IR domes for missiles guidance. Fluoride glasses when elaborated as optical fibers or channel waveguides and when doped with appropriate lanthanides, are original optical devices for laser operations lying from the mid IR to the UV region where light emission is characterized by up-conversion phenomena. The same devices have also found industrial applications in telecommunications as a new generation of optical amplifiers operating in the ultra-transparency window of the silica fiber.     

ORGANIC CHELATING REAGENT ON REDOX ADSORPTION OF ACTIVATED CARBON FIBER TOWARDS Au^3+

Organic chelating reagent influences upon the redox adsorption of activated carbon fibertowards Au3- were systematically investigated. The experimental results indicated that the presenceof organic chelating reagent on activated carbon fiber strongly affects adsorption capacity ofactivated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three timesby the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended onthe pH value of adsorption and temperature.     

ADSORPTION CAPACITY OF ACTIVATED CARBON FIBER FABRIC IN CYANIDE LEACHING LIQUOR OF GOLD ORES

1. INTRODUCTION Reclamation of gold in liquid of gold with activated carbon fiber (ACF) is reported. ACF possessed numerous advantages, such as high adsorption capacity, great adsorption rate and high recovery of gold. It was generally considered tha…     

Estimation on the optic loss for acrylic polymers by theoretical modification

Various fluorinated/chlorinated polymers were synthesized and characterized by FT-IR and NMR. Also, theoretical optic loss of the POF were investigated and proposed for the purpose of finding a definite rule of the optic loss.From the computation of the results, the modified equation was theoretically deduced, and the optic loss of each prepared polymer was measured and compared with the calculated optical loss of polymers. Also, it was found that the optic loss from the modified equation fitted well with the experimental data.     

Statistical Modeling of Unidirectional Fibrous Structures

Some textiles such as slivers, rovings, yarns, and highly oriented polymer fibers as well as the reinforcing structure of unidirectional composites have a kind of unidirectional or quasi-unidirectional fibrous structures. The statistical properties of their structure and strength can be modeled by using idealized fiber bundles as model elements. In this study the tensile test process of unidirectional short fiber structures is modeled for different damage types using the instantaneous fracture model and special idealized fiber bundles for gradual damages such as fiber breakage and fiber slippage. Constant fiber length and exponential fiber length distribution as extreme cases of the Erlang distributions were used for analysis. In case of exponential fiber length distribution and constant fiber breaking strain simple analytical relationships between the mean tensile strength and the fiber length were derived and compared to those for constant fiber length and written in a general form which is valid for all the damage modes discussed. The convex linear combination of the solutions for exponential fiber length distribution and constant fiber length was proposed to use for cases when the variation coefficient of the fiber length is between 0 and 1. The practical applicability of the results was demonstrated by identifying the relationship between the mean tensile strength and the average molecule mass of polypropylene fibers that made it possible to estimate the critical molecule mass and the tensile strength of the molecules without further measurements.     

氙在活性炭纤维吸附床上穿透的动力学模型

研究了氙在活性炭纤维吸附床上的穿透特性,采用Boltzmann分布函数理论模拟了穿透曲线,根据Boltzmann函数曲线推导了穿透时间方程,给出了半穿透时间的理论表达式,较好地解释了实验数据。     

四川某金矿中非金属单矿物的元素分析及意义

利用中子活化分析法对四川某地区的非金属单矿物(热液脉矿物)的元素进行了测试,并利用元素地球化学研究方法对元素间的相关关系进行了分析。结果表明,在该地区可以利用元素间的伴生关系指导找矿。     

不同的灰熔点调控方式对煤灰熔融特性的影响

对两种原始煤灰进行混合,并分别搭配不同的添加剂,得到3种元素组成相同的煤灰,灰熔点测试结果显示,三者的灰熔点存在较大差异。结合X射线衍射技术和SEM-EDX(扫描电子显微镜与能谱联用)分析了3种煤灰(>800 ℃)在高温时的矿物质转化过程。结果表明,不同的灰熔点调控手段对不同煤的影响是不同的。原因是高温时矿物质组成不仅与煤灰化学元素组成相关,更与元素在矿物质中的赋存状态有关。两者共同决定了煤灰的熔融特性。     

辛基羟肟酸浮选氟碳铈矿机制研究

采用纯矿物浮选的方法,以松醇油为起泡剂,研究了氟碳铈矿在辛基羟肟酸钠为捕收剂体系下的浮选行为,在p H=7~11范围内,氟碳铈矿回收率大于96%,尤其在p H=9附近,氟碳铈矿的可浮性最好,回收率接近100%;采用傅立叶红外光谱(FT-IR)和X射线光电子能谱(XPS)手段进行作用机制研究,红外光谱表明,辛基羟肟酸钠在氟碳铈矿表面发生了化学吸附;XPS结果表明,氟碳铈矿表面可能只存在-C=O-RE-O-N-一种五元环螯合物;结合La3+和Ce3+离子溶液化学和氟碳铈矿浮选行为,推测La(OH)2+,La(OH)2+,Ce(OH)2+和Ce(OH)2+是存在于氟碳铈矿表面的浮选活性点,并推测了辛基羟肟酸在氟碳铈矿表面作用的模型。     

Flame-retardant Wrapped Ramie Fibers towards Suppressing “Candlewick Effect” of Polypropylene/Ramie Fiber Composites

In this work, a flame-retardant polypropylene(PP)/ramie fiber(RF) composite was prepared. The ramie fibers were wrapped chemically by a phosphorus- and nitrogen-containing flame retardant(FR) produced via in situ condensation reaction so as to suppress their candlewick effect. Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM) demonstrated that the ramie fibers wrapped chemically by FR(FR-RF) were obtained successfully. Thermogravimatric test showed that the PP/FR-RF composite had more residue and better thermal stability at high temperatures than the PP/RF composite. Cone calorimeter(CC) results indicated that the peak of heat release rate(PHRR) and total heat release(THR) correspondingly decreased by 23.4% and 12.5% compared with the values of neat PP/RF. The PP/FR-RF composite created a continuous and compact char layer after the combustion. Combining FTIR analysis of char residue after CC test with heat conduction coefficient results, it could be concluded that the charring of FR on RF greatly weakened the candlewick effect of RF, and more char residue in the RF domain facilitated the formation of more continuous and compact char layer in the whole combustion zone, consequently protected PP composites during combustion, resulting in the better flame retardancy of PP/FR-RF composite than that of PP/RF composite.