Study of eye drops dispensing and dose variability by using plastic dropper tips

The application of eye drops from flexible dropper bottles fitted with different types of dropper tips is associated with the high variability of eye drop weights. The aim of this report was to investigate the simultaneous effect of three factors influencing the mean weight of drops dispensing from two plastic dropper tips. Using a designed experiment (Box-Behnken), the effect of the concentration of benzalkonium chloride solutions (BAC) in the range of 0-0.02%, the dispensing angle from 90° to 30° from horizontal, and the residual volume of liquid in the dropper bottle from 4 to 10 mL on the mean drop weights were examined. The significant effect of the increase in BAC concentration resulted in a linear decrease in drop weights for both of the dropper tips investigated. The significant effect of the dispensing angle was influenced by the dropper tip design. For the dropper tip A, the effect of the dropper tip tilt was described by the quadratic equation with a minimum, which corresponded to the dispensing angle equal to that of 48° from horizontal. Below this angle, the increase in drop weights occurred due to the drop formation from the wetted external surface of the tip orifice. The linear decrease in drop weights in response to the decrease in dispensing angle was detected for the dropper tip B. The regression equations and the contour line plots obtained allowed the drop weights to be estimated for the actual combinations of both the BAC concentration and the dispensing angle. The effect of the residual volume was found to be non-significant. Based on the formula of Tate's law, the direct proportion between surface tension of a solution and the radius of the effective perimeter of a dropper tip can be used to estimate the theoretical maximal weight of drops at the dispensing angle of 90°. Using the stalagmometric values of surface tension of the BAC solutions, the maximal drop weights were estimated for both of the dropper tips investigated. A comparison between the theoretical and the experimentally measured drop weights enabled the dropper tips behavior to be discussed by using Harkins and Brown correction factor F. The F-value of 0.74 noted for the dropper tip A differed from that of stalagmometer F-value (0.61) indicating a deviation from the simple drop formation process in answer to more complicated design of the dropper tip A. On the other hand, the F-value of 0.6 observed for the dropper tip B demonstrated the better consistency with stalagmometry. As a result, the dropper tip B with the linear decrease of drop weights in response to the increased concentration of BAC and the decreased dispensing angle without the adverse external drop formation could be recommended in real drop dispensing.     

非职业投资者利用综合收益信息的眼动研究

目的通过眼动研究深入考察非职业投资者利用综合收益信息的过程,以及列报方式对估值决策的影响。方法采用眼动技术追踪了综合收益列报的"一表法"和"两表法"下86名MBA学生信息获得、认知和利用的过程。结果 (1)非职业投资者按照呈报的顺序阅读财务报告,证实了"顺序搜寻"信息策略。(2)列报方式不影响信息的获得,但显著影响综合收益信息区域的注视点时长、注视点个数和观察时长。(3)"一表法"下非职业投资者能更好地识别综合收益增长与公司投资价值之间的关系。结论列报方式通过信息认知来影响信息利用,"一表法"有利于非职业投资者改善估值决策。     

Using response surface methodology to assess the effects of iron and spent mushroom substrate on arsenic phytotoxicity in lettuce (Lactuca sativa L.)

The effects of iron (Fe) and spent mushroom substrate (SMS) arsenic (As) phytotoxicity towards lettuce in artificial soils were investigated to separate the adverse soil parameters relating to As toxicity using a response surface methodology. SMS induced the root elongation of lettuce in both control and As-treated soils. However, in phytotoxicity test using a median effective concentration (EC₅₀) of As, Fe and the interaction between both parameters (Fe*SMS) significantly affected EC₅₀, which explained 71% and 23% of the response, respectively. The refined model was as follows: EC₅₀ of As (mg kg⁻¹) = 10.99 + 60.03 × Fe − 10.50 × Fe*SMS. The results confirmed that the soil parameters relating to the As mobility in soils were important factors affecting its toxicity. In conclusion, Fe significantly reduced the As phytotoxicity. However, although SMS enhanced the root elongation, SMS in As-treated soils decreased EC₅₀ of As on the root growth via its interaction with Fe. Despite the limitations of the artificial soils and range of parameters studied, the application of this statistical tool can be considered a powerful and efficient technique for interpretation and prediction of the complicated results caused by the interactions between many factors within the soil environments.     

塑性变形诱发表面自纳米化的研究及其应用

详细介绍了强烈塑性变形诱发表面自纳米化的研究进展,即形变诱发表面自纳米化的方法与设备、表面自纳米化层的结构及其表征、形变诱发表面自纳米化的机理及其相关应用,并展望了形变诱发表面自纳米化的研究与应用.     

大视场自由曲面复眼设计研究

在大视场小体积的人造复眼结构中,倾斜的边缘子眼成像时存在较大的轴外像差。提出一种复眼结构,利用光线在子眼中的折转与自由曲面矫正像差,提高了边缘子眼的成像质量,进而增大了复眼结构的视场角。设计出5组子眼对180°视场成像,每组对应特定的视场范围。利用光学仿真软件CodeV对5组子眼分别做了光学仿真,得到了各组子眼的像差曲线,光学传递函数MTF曲线。结果表明,在整个180°视场范围内,频率为100 lp/mm时,MTF值均大于0.2,畸变在30%以内,复眼具有良好的成像质量。     

Optimization,Kinetics, and Equilibrium Studies on the Removal of Lead(II) from an Aqueous Solution Using Banana Pseudostem as an Adsorbent

Natural adsorbents such as banana pseudostem can play a vital role in the removal of heavy metal elements from wastewater. Major water resources and chemical industries have been encountering difficulties in removing heavy metal elements using available conventional methods. This work demonstrates the potential to treat various effluents utilizing natural materials. A characterization of banana pseudostem powder was performed using environmental scanning electron microscopy (ESEM) and Fourier-transform infrared (FTIR) spectroscopy before and after the adsorption of lead(II). Experiments were carried out using a batch process for the removal of lead(II) from an aqueous solution. The effects of the adsorption kinetics were studied by altering various parameters such as initial pH, adsorbent dosage, initial lead ion concentration, and contact time. The results show that the point of zero charge (PZC) for the banana pseudostem powder was achieved at a pH of 5.5. The experimental data were analyzed using isotherm and kinetic models. The adsorption of lead(II) onto banana pseudostem powder was fitted using the Langmuir adsorption isotherm. The adsorption capacity was found to be 34.21 mg·g^–1, and the pseudo second-order kinetic model showed the best fit. The optimum conditions were found using response surface methodology. The maximum removal was found to be 89%.     

Modelling the Effect of Initial Grain Size on Dynamic Recrystallization Using a Modified Cellular Automata and a Adaptive Response Surface Method

A modified cellular automata (CA) model of dynamic recrystallization (DRX) and a flow stress-based nucleation parameter identification method have been developed.In the method,the modified CA model,which takes the role of deformation degree on nucleation behavior into consideration,is coupled with an adaptive response surface model (ARSM) to search for the optimum nucleation parameter.The DRX behavior of an oxygen free high conductivity (OFHC) copper with different initial grain sizes has been taken as an e...     

AZ31镁合金表面气相沉积不锈钢薄膜的实验研究

利用真空蒸发镀膜技术在镁合金表面沉积不锈钢薄膜是提高镁合金防腐性能的新尝试.本研究利用该技术在AZ31上成功制备了不锈钢薄膜.通过在5%NaCl溶液中的浸入实验和极化实验考察了腐蚀性能,发现镀膜后耐蚀性显著降低.另外,镀膜后的显微硬度也未有明显提高.利用AFM,SEM,EDX等分析手段对薄膜进行了观察和检测,发现耐蚀性变差的原因主要是薄膜表面存在贯穿性的微米级孔洞和Cr元素分布不均匀造成的.     

Design and Analysis of Storing Experiments: A Case Study

In order to achieve robust and stable food products of desired quality and characteristics, all stages of the food production process, including storage conditions, should be considered during product development projects. This article describes a multistage production development project on low-fat mayonnaise, where experimental design was used to set up a pilot plant study involving ingredient factors, processing factors, and storage factors and their effect on mayonnaise viscosity. The article discusses three alternative empirical modeling approaches to analyze the data—namely, a simple graphics approach, a robustness approach, and a mixed models approach—considering their multistratum (split-plot) structure and repeated measurements of each subsample. In the case study, all information relevant for business decisions was obtained through the combination of graphical analysis and the robustness approach. This information could also be extracted by a practitioner, while the mixed model analysis clearly requires a graduate statistician. In order to obtain valid and useful information for the practitioner in an efficient way, the authors believe that, usually, the first two approaches would be sufficient. The more complex mixed model strategy might be advisable if a deeper understanding is required or desired.     

Investigating the effects of feeding properties on rock breakage by jaw crusher using response surface method and gene expression programming

The present study investigates the effects of feeding properties on rock comminution by a laboratory-scale jaw crusher. For this purpose, detailed crushability tests were carried out on four different rock types to assess their degree of rock crushability (DRC). Various feeding sizes (9.5 – 19 mm) and quantities (500 – 1500 g) were adopted to reveal the choke feeding intensity during crushing actions. The efficiency of feeding properties was investigated through the response surface methodology (RSM). The RSM results demonstrated that the characterized feeding size (F₈₀, mm) dominates the general size reduction, whereas the feeding quantity (m_f, g) is associated with the crushing energy consumption and product flakiness. Therefore, the choke feeding intensity has a direct relation to the m_f and F₈₀. In addition, novel gene expression programming (GEP) models were employed to generate empirical formulations to predict the DRC parameters. The established GEP models have a satisfactory estimation capability. Therefore, the DRC of the investigated rocks can be optimized through the proposed GEP models based on the coupling variables of m_f and F₈₀.     

剧烈塑性变形法制备纳米晶材料Ni和Ni／SiO2

剧烈塑性变形法是制备纳米材料的一种新方法。报道由此法制备的纳米晶Ｎｉ和纳米晶复合材料Ｎｉ／ＳｉＯ２的热稳定性和力学性能的研究结果。     

采用仿真型与透视型模型进行智力切割测试(MCT)的空间认知效果的研究

在智力切割测试(MCT:Mental Cutting Test)中,影响评价空间认知能力效果的因素很多,其中采用不同类型的立体模型测试时,MCT测试的正确率不同.在形状判断问题中,采用仿真型模型代替透视型模型进行MCT测试时正确率提高.在量判断问题中,采用仿真型或透视图模型进行MCT测试时正确率没有太大差异.这说明借助计算机产生的仿真型模型可以帮助学生更好地理解形体.     

地铁隧道钻爆施工地表振动速度特征研究

为了研究地铁隧道爆破振动规律并有效地控制爆破振动危害,对贵阳地铁二号线一期工程隧道爆破开挖进行实时监测,然后对监测数据进行回归分析,计算出爆破地震波衰减系数α和k值,并利用大型有限元软件LS-DYNA对爆破施工进行数值模拟,结果表明:用萨道夫斯基公式对地铁隧道掘进的地表振动速度进行拟合时,隧道掘进前方比掘进后方的相关性较好,数值模拟计算所获得的地表振动速度规律与现场监测结果基本一致,地铁隧道掌子面后方已开挖区的地表振动速度存在放大现象。因此,在进行爆破施工方案设计时,必须考虑已开挖区的地表振动速度放大的影响,保障掌子面后方地表建筑物的安全。     

钢筋混凝土梁静态破裂试验与应变分析

为研究钢筋混凝土构件的静态破裂规律,采用预留钻孔和内部预埋应变砖的方法,进行了钢筋混凝土梁的静态破裂试验。通过内置12个应变砖测得的钢筋混凝土梁内部应变以及梁破裂面的裂缝宽度变化,分析了钢筋混凝土梁在静态破裂过程中的应变变化和破坏形态。试验结果表明:孔内膨胀应力作用下,裂缝优先由孔周边向最小抵抗线方向的自由面扩展;同一排药孔位置的应变大小以及变化趋势大致相同;逐排灌孔的静态破碎方式能够顺利破裂钢筋混凝土构件,构件呈梅花状破裂。研究结果为静态破裂技术在钢筋混凝土工程中的应用提供了试验参考依据。     

胃粘膜正常、肠化和腺癌组织基因组DNA的拉曼光谱分析

本文提出结合生物组织DNA提取技术和拉曼光谱技术来系统研究胃癌不同发生过程中的组织DNA空间结构的方法.实验中,首先提取涉及胃癌发病过程中的胃粘膜正常上皮组织、肠化组织和腺癌组织的基因组DNA,分别对其进行拉曼光谱检测,根据拉曼谱图特征,详细分析了基因组DNA的结构变化.实验结果表明,胃粘膜正常组织DNA中有稳定的磷酸骨架;肠化组织基因组DNA拉曼特征峰在1 090 cm~(-1)处谱峰强度低于1 050 cm~(-1)处谱峰强度,表明其磷酸骨架变得不稳定,其它位置的谱峰与正常组织相似;腺癌组织基因组DNA拉曼特征峰在1090 cm~(-1)附近出现双峰,其相对于1050 cm~(-1)处谱峰强度更强,提示DNA有可能出现断链并再次形成了稳定的磷酸骨架,在950 cm~(-1)、1 010cm~(-1),1 100～1 600 cm~(-1)波段的特征谱峰与正常组织DNA相比变化也较犬,说明脱氧核糖和碱基可能由于DNA断链也随之改变.这些结果提示胃癌的发生过程中DNA结构变化过程可能是:胃粘膜正常组织具有稳定的DNA磷酸骨架,在致病因素作用下发展为具有不稳定磷酸骨架DNA的肠化组织,最后组织DNA磷酸骨架断裂并重新形成稳定的DNA磷酸骨架,致胃癌发生.     

微弧氧化与磁控溅射复合处理的钛合金表面耐磨性研究

微弧氧化处理后的钛合金,表面形成的多微孔氧化膜可使其摩擦因数降低且耐磨性得到提高,但这还不能满足某些使用要求.在微弧氧化的基础上再利用脉冲偏压式磁控溅射技术在钛合金表面沉积氮化钛涂层.球-盘磨损试验表明,与微弧氧化相比,其摩擦因数进一步降低且耐磨性进一步提高,这主要是沉积富钛氮化钛使氧化膜的微孔得到了部分或全封闭的覆盖.     

VARI工艺制备典型平面及曲面构件的流道设计模拟研究

对典型平面及典型曲面构件进行了VARI工艺模拟分析,分别采用不同的模拟方案对两类构件进行流道设计模拟研究,由此得出了两类构件工艺流道设计的异同点,旨在针对不同构件的结构特点,选择最佳的注射方式及合理的流道设计方案,从而为模具设计及构件制造提供重要依据。     

Prediction of Delta Ferrite Content and Effect of Welding Process Parameters in Claddings by FCAW

This article discusses the influence of welding process parameters on the content of delta ferrite in the claddings of AISI 317L, deposited onto IS: 2062 structural steel plate by the flux cored arc welding (FCAW) process. Measurement of delta ferrite within the cladding often gives important insight into the future mechanical and corrosion resistant behavior of the cladded structures. To predict and control the amount of residual ferrite, regression models were developed in terms of process parameters, using the data obtained from experiments. The experiments were conducted by using a central composite rotatable design of experiments. The study revealed that the cladding process parameters have influence over the formation of delta ferrite.     

聚全氟乙丙膜电子束引发预辐射接枝AA和SSS制备阳离子交换膜的性能

利用电子束引发预辐射接枝技术,在聚全氟乙丙烯(FEP)膜上接枝丙烯酸(AA)和对苯乙烯磺酸钠(SSS)两单体,制备出一种含羧酸基团和磺酸基团的阳离子交换膜,接枝率越高,接枝膜的吸碱性能越好。差示量热扫描及X射线衍射测试表明,接枝膜结晶度随接枝率的升高而降低。这是接枝膜中FEP组份的“结晶变形”及接枝链对晶区的“稀释作用”综合影响的结果。     

Fabrication of a 60‐nm‐Diameter Perfectly Round Metal‐Dot Array over a Large Area on a Plastic Substrate Using Nanoimprint Lithography and Self‐Perfection by Liquefaction

Typically, nanopatterning on plastic substrates has poor fidelity, poor adhesion, and low yield. Here the proposal of and the first experiment using a new fabrication method that overcomes the above obstacles and has achieved arrays of 60‐nm‐diameter, perfectly round metal dots over a large area on a polyethylene terephthalate (PET) substrate with high fidelity and high yield is reported. This new method is based on the use of a thin hydrogen silsesquioxane (HSQ) layer on top of PET, nanoimprint lithography, and self‐perfection by liquefaction (SPEL). The HSQ layer offers excellent thermal protection to the PET substrate during SPEL, as well as good surface adhesion and etching resistance. Nanoimprinting plus a lift off created a large‐area array of Cr squares (100 nm × 130 nm) on HSQ and SPEL changed each Cr square into a perfectly round Cr dot with a diameter of 60 nm, reducing the Cr footprint area by 78%. Compared to bare PET, the use of HSQ also reduced the variation in the diameter of the Cr dots from 11.3 nm (standard deviation) to 1.7 nm, an improvement of over 660%. This new technology can be scaled to much larger areas (including roll‐to‐roll web processing) and thus potentially has applications in various fields.