Lith显影的自催化性质

Lith显影与常规显影不同,在一个较宽的曝光范围内,颗粒群体的还原是平行的而不是顺序的。顺序还原时,乳剂层的密度增长速率只是给出了颗粒间显影诱导期分布的信息。只有平行还原时,密度增长速率才给出了单个乳剂颗粒还原速率的信息。换言之,只有在颗粒群体平行还原时,表现显影动力学才具有单个乳剂颗粒的显影特征:在显影诱导期结束后开始了自催化的还原阶段。Lith显影的自催化性质应该归因于颗粒群体还原的平行方式。     

Lith显影的诱导期条件

Lith效应的产生要求严格的显影诱导期条件。Lith显影的诱导期条件要靠显影促进和显影抑制两种作用的结合来实现。半醌的显影促进作用缩短了显影颗粒邻近的载有较大潜影颗粒的显影诱导期,使颗粒间显影诱导期分布变窄。显影中心钝化现象的发生延长了载有较小潜影颗粒的显影诱导期,导致了表现显影诱导期对曝光量的依赖关系。Lith效应是两种作用在不同曝光区以不同程度发生的平衡结果。     

感光乳剂颗粒中杂质中心在感光过程各阶段的演变及其诠释——(Ⅰ)感光乳剂颗粒中最大潜影中心相对大小频率分布的测定

本文根据显影过程电极理论的基本概念和单个乳剂颗粒显影过程的若干动力学特征,认为在特定的条件下,单个乳剂颗粒的显影过程可以分作两个阶段:自催化阶段和快速还原阶段。在自催化阶段,决定过程速度的是显影液/潜影中心界面上电子转移的步骤,这时过程的速度与显影中心表面积的大小成正比,反应具有自催化的性质。在快速还原阶段,乳剂颗粒内部填隙银离子向显影中心附近的迁徙成为决定过程速度的步骤;这一阶段与自催化阶段相比,持续的时间极短。在这种假设的基础上,通过乳剂颗粒显影时间的频率分布求出颗粒中最大潜影中心相对大小的频率分布。该方法适用于在同样的原始乳剂和显影的条件下比较乳剂颗粒中最大潜影中心的相对大小频率分布的情况。     

显影灰雾形成机理的研究 Ⅰ.显影灰雾形成过程的受阻显影研究

本文利用受阻显影和电镜方法,对比了显影灰雾与乳剂灰雾的形成过程。研究表明,乳剂灰雾是由于在乳剂制备过程中形成的灰雾中心而引起的,这种灰雾中心在显影过程中的行为与潜影中心一样,显影在少数中心开始,最后生成丝团状银。显影灰雾的形成则经过成核和生长两个不同的阶段:藉显影物分子与乳剂颗粒表面的碰撞而生成银核,一旦稳定的银核生成,随后就能以较快的速率继续生长。因此在一般显影的条件下,显影灰雾的形成需要一个较长的显影引发期。成核在颗粒表面的许多部位发生,同时生长,最后生成紧密的银块。溴化钾和季铵盐对成核速率有显著影响,这表明了乳剂颗粒表面负电荷在显影成核阶段中的作用。未敏化乳剂的显影灰雾中心在颗粒表面上的分布是随机的,而硫敏化乳剂的显影灰雾中心则优先在八面体的棱上生成。     

不同取代基的苯酰肼的感染显影及其机理

本文研究了五种苯酰肼化化合物（通式为ＲｐＨ－ＮＨＮＨ－ＣＯＲ＇）对卤化银乳剂感光性能的影响。利用循环伏安、气－质联仪等方法研究了苯酰肼感染显影的作用机理及其影响因素。实验结果表明，通过苯酰肼的感染显影可获得高感、高反差的效果。影响感染显影程度的大小、除了与取代基 Ｒ，Ｒ＇结构有密切关系以外，还以乳剂的种类、胶银比、苯酰肼在上卤化银颗粒上的吸附等因素有一定关系。另外也苯酰肼衍生物取代基结构不同，其作     

高温状况下如何冲洗黑白负性胶片

每年6～9月份,我国大部分地区气温均较高,平均在30℃左右,有的地区甚至可达到35～38℃,即使是冷水温度也超过25℃,如此高的温度显然已超出了20℃的胶片标准冲洗温度.当用常规的显影方法冲洗胶片时,由于显影温度高,就会提高显影主药活性,加快显影速度,使卤化银颗粒变粗,灰雾增加,产生污染,导致乳剂层过度膨胀、龟裂、起皱和溶化,使胶片受到损坏.为了保证胶片的冲洗质量,使它的感光度、颗粒度、影像反差、密度等主要技术指标与20℃标准显影条件下所获得的效果大体一致,就必须采用一套有别于常温状况下冲洗的加工方法.     

新型中空卤化银颗粒乳剂的制备和性能研究 Ⅲ.中空卤化银颗粒乳剂感光性能的研究

本文应用表面显影、Ｄｅｍｂｅｒ效应、化学成熟、光谱增感等方法,对照实心立方体溴化银乳剂研究了中空卤化银微晶的结构与光物理性质及感光性能的关系．实验结果表明：（１）中空卤化银的潜影在孔洞处优先形成;（２）中空卤化银微晶中位错、缺陷较多,其填隙银离子浓度较大,电子陷阱较多;（３）中空颗粒表面反应活性高,感光度高,光谱增感效果好;（４）中空颗粒乳剂其反差较大,最大密度较高;（５）上述结果均可归因于中空卤化银微晶所特有的孔洞结构．     

铱盐在AgBr乳剂中的作用

用(NH_4)_3IrCl_6(Ⅲ)和(NH_4)IrCl_6(Ⅳ)分别对立方体AgBr乳剂颗粒表面和内部进行敏化,用表面显影和内部显影的方法,对铱盐在乳剂颗粒中的作用进行了研究。实验表明,经铱表敏的AgBr乳剂表面感光度增加,而铱内敏的AgBr乳剂表面感光度降低,内部感光度增加;铱内敏并经灰化的乳剂在曝光后能形成直接正像。这是因为经化学灰化的铱内敏乳剂在曝光后,光生电子被乳剂颗粒内部的铱中心捕获而形成内潜影,光空穴则破坏颗粒表面的灰化中心,使其不能显影。因此,我们认为铱在乳剂颗粒内部起着电子陷阱的作用。     

酰基苯肼的感染显影及反差促进剂的作用

研究了六种结构不同的酰基苯肼化合物(通式:R—PhNH—NH—COR′)对卤化银乳剂感光性能的影响。结果表明,感染显影作用程度与酰基苯肼的结构有密切的关系。另外本文还就反差促进剂(醇类化合物和胺类衍生物)的作用及其机理进行了较深入的研究。事实说明,显影液中加入反差促进剂,不但能消除单独使用酰基苯肼时出现的“自阻”效应,而且还大大促进了感染显影的进行,提高了乳剂的反差和感光度。同时,本实验在应用高压液相色谱、色-质联仪、顺磁共振等方法对酰基苯胼的还原反应产物及反应中间物进行分析的基础上,更加明确地解释了感染显影和反差促进的作用机理。     

感光乳剂颗粒中杂质中心在感光过程各阶段的演变及其诠释——Ⅲ.两类中心在氧化剂作用下的行为

本文利用显影动力学方法研究了感光乳剂颗粒中两类不同大小的杂质中心在氧化剂作用下的行为。结果表明,经氧化处理后,有较大一类中心的乳剂颗粒形成潜影的能力大大减弱,而有较小一类中心的乳剂颗粒在未曝光的情况下显影的速度有所增长。本文将这两种现象均归因于杂质中心为氧化剂所氧化,并且认为,有较小一类中心的乳剂颗粒经氧化处理后,其显影速度之所以增长,是由于杂质中心遭受破坏以后,颗粒周围的明胶囊上原先为杂质中心所遮蔽的缺口暴露,从而使乳剂颗粒在该部位失去了明胶的保护作用,以致在显影液中得以较快地还原。上述现象在未敏化、硫敏化以及硫加金敏化的情况下都同样存在。     

Migration of Corundum Crystal Basal Surfaces in a Matrix of Fine Alumina Grains and Anorthite Liquid

Corundum crystals with basal surfaces have been embedded in a matrix of fine alumina grains and 15 wt% anorthite and heat treated at 1620°C. During the heat treatment, the fine alumina grains and the corundum crystals grow. The corundum basal surfaces that have been scratched grow most rapidly and those with a low dislocation etch pit density grow most slowly. The corundum basal surfaces with a high dislocation etch pit density grow at an intermediate rate. When the matrix alumina grains are very fine in the initial heat-treatment stage, all three corundum basal planes grow at approximately the same rate, and, as the matrix grains coarsen, the growth rates of the basal surfaces diverge. The plots of the migration rates of the basal surfaces and the inverse average size of the matrix grains are non-linear and depend on the estimated dislocation content at the basal surfaces. Such a growth behavior of the basal surfaces resembles those of the singular surfaces of a single crystal growing in a fluid. The results show that dislocations in the grains are important in abnormal growth of grains in liquid matrix.     

Kinetic study of emulsion copolymerization of ethyl methacrylate/lauryl methacrylate in propylene glycol,stabilized with poly(ethylene oxide)–block–polystyrene–block–poly(ethylene oxide) triblock copolymer

The kinetics of emulsion copolymerization of ethyl methacrylate (EMA)/lauryl methacrylate (LMA) in propylene glycol is very similar to the emulsion copolymerizations of water‐soluble monomers in water because of the high solubility of EMA/LMA in propylene glycol. The initial rate of polymerization depends only on initiator concentration and is not affected by either monomer concentration or stabilizer concentration. The overall rate of polymerization is only slightly dependent on monomer concentration and stabilizer concentration and is independent of initiator concentration. The final particle number density increases with increasing amount of stabilizer and decreases with increasing monomer concentration. The total surface area increases with stabilizer concentration and is not governed by either initiator concentration or monomer concentration. Homogeneous nucleation is the dominant mechanism of particle nucleation, as shown by the kinetic data on seeded polymerization and monomer partition behavior. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1691–1704, 2001     

油水乳化液流变性研究进展

综述了油水乳化液流变性研究进展，介绍了目前国内外乳化液流变性的研究情况、乳化液的流变模式及乳化液流变性的评价方法。乳化液的剪切应力-剪切速率关系明显受油滴尺寸的影响，在含油量一定时，表观黏度随油滴尺寸的减小而增加。绝大多数乳化液在低剪切速度下(低于50s^-1)，呈现剪切变稀行为；在剪切速率超过1000s^-1时呈现牛顿行为。高含水原油的视黏度是温度、含水率以及剪切速率的函数。介绍了乳化液的3种流变模式，并给出了流变性评价方法实例。提出了油水乳化液流变性研究的发展方向。     

Elongation rheology of polyolefins and its relation to processability

The rheology of a variety of polyolefin resins, and resin blends, has been examined under conditions of constant strain rate elongation. These include high, low, and linear low density polyethylene, as well as polypropylene, commercially modified polypropylene, and elastomer blends with polypropylene. Two distinctly different classes of behavior are apparent in the viscosity growth patterns during uniaxial extension. Some resins display unbounded stress growth even at low strain rates. Others quickly attain a time independent value of extensional viscosity even at increased strain rates. The former behavior is identified with favorable blow molding behavior, while the latter was characteristic of resins unsuitable for such processing. The class of elongation behavior depends not only on resin type, but may be influenced by molecular weight distribution or blend morphology.     

Abnormal Grain Growth in Alumina with Anorthite Liquid and the Effect of MgO Addition

Abnormal grain growth (AGG) in alumina with anorthite liquid has been observed with varying anorthite and MgO contents, at 1620°C. When only anorthite is added to form a liquid matrix, the grain–liquid interfaces have either flat or hill-and-valley shapes indicating atomically flat (singular) structures. The large grains grow at accelerated rates to produce AGG structures with large grains elongated along their basal planes. This is consistent with the slow growth at low driving forces and accelerated growth above a critical driving force predicted by the two-dimensional nucleation theory of surface steps. With increasing temperature, the AGG rate increases. The number density of the abnormally large grains increases with increasing anorthite content. The addition of MgO causes some grain–liquid interfaces to become curved and hence atomically rough. The grains also become nearly equiaxed. With increasing MgO content the number density of the abnormally large grains increases until the grain growth resembles normal growth. This result is qualitatively consistent with the decreasing surface step free energy associated with partial interface roughening transition.     

Composition segregation and grain growth in (K0.5Na0.5)NbO3 piezoceramics prepared by two-step cold sintering process

Cold sintering process (CSP) is a new method to prepare ceramics under quite low temperature. In this work, two-step CSP under different pressures was employed to prepare (K_0.5Na_0.5)NbO₃ (KNN) ceramics. The density of KNN green pellets can be raised by enhancing the pressure of second-step CSP. Energy-dispersive spectroscopy reveals the composition segregation of A-site cations in large grains. The dissolution rate of K⁺ in an aqueous medium is faster than Na⁺, and high pressure can accelerate K⁺ dissolution, resulting in more Na⁺ in some grains. Besides, the diffusion rate of Na⁺ in grains is better than K⁺, which promote the grains growth. Finally, the piezoelectric property is improved even with low ceramic density due to the larger grains, which possess the higher performance composition. This result demonstrates that the pressure and inhomogeneous dissolution of alkali metal ions among CSP play an important role in grain growth and piezoelectric enhancement.     

硫氰酸钾在外延卤化银乳剂制备中的作用

外延卤化银乳剂一般都是在有机调变剂作用下制备出来的,而有机调变剂会给乳剂体系带来一些不利因素。本文中用无机酸盐KSCN作外延乳剂调变剂制备出了一系列外延乳剂,并利用电子透射显微技术研究了硫氰酸钾对主体乳剂颗粒的浸蚀作用和浸蚀部位,指出了浸蚀部位和外延生长位置间的关系,对八面体及薄片颗粒外延乳剂的形貌和晶态进行了研究和描述,对不同外延成份的薄片颗粒外延乳剂的形貌也进行了描述,证明了无机酸盐KSCN可以用作外延调变剂。     

Effect of Sintering Atmosphere on Grain Shape and Grain Growth in Liquid-Phase-Sintered Silicon Carbide

We investigated the effects of the sintering atmosphere on the interface structure and grain-growth behavior in 10-vol%-YAG-added SiC. When α-SiC was liquid-phase-sintered in an Ar atmosphere, the grain/matrix interface was faceted, and abnormal grain growth occurred, regardless of the presence of α-seed grains. In contrast, when the same sample was sintered in N₂, the grain interface was defaceted (rough), and no abnormal grain growth occurred, even with an addition of α-seed grains. X-ray diffraction analysis of this sample showed the formation of a 3C (β-SiC) phase, together with a 6H (α-SiC) phase. These results suggest that the nitrogen dissolved in the liquid matrix made the grain interface rough and induced normal grain growth by an α→β reverse phase transformation. Apparently, the growth behavior of SiC grains in a liquid matrix depends on the structure of the grain interface: abnormal growth for a faceted interface and normal growth for a rough interface.     

Effect of Crystallization on the Auger Electron Signal Decay in an Li2O·2SiO2 Glass and Glass-Ceramic

Problems associated with Auger analysis of glasses are well recognized. When an electron beam impinges on the surface of a glass specimen, the Auger signal produced by the alkali species decreases with exposure time. The rate at which the signal decays depends on the glass composition, beam current density, accelerating potential of the primary beam, and substrate temperature, all of which must be carefully controlled to obtain a reliable analysis. A similar decay of the alkali Auger signal is observed for glass-ceramic systems. The rate of decay for the crystalline phase is different from that for the glass and depends on the extent of crystallization. This behavior may provide a basis for using Auger electron spectroscopy for microstructural as well as compositional analysis.