Does placebo effect exist in contact lens discomfort management?

PurposeTo study the effect of daily disposable contact lens (DDCL) refitting in monthly contact lens (CL) wearers suffering from contact lens discomfort (CLD), and to assess if there is a placebo effect associated with this CLD intervention.MethodsSymptomatic CL wearers, according to the Contact Lens Dry Eye Questionnaire 8 (CLDEQ-8 ≥ 12 points), were divided into two groups. The study group was provided with DDCLs (delefilcon A) and the control group with a masked pair of their habitual monthly CLs (placebo effect) and were assessed after one month. Then, the control group was provided with the same DDCLs and evaluated one month later. The symptoms were recorded with the CLDEQ-8 and global rating of change scale (GRCS). Non-invasive tear break-up time (NITBUT), conjunctival hyperaemia, fluorescein staining, and lid wiper epitheliopathy (LWE) were evaluated. Changes between visits, groups, and the effect of each intervention were analysed.ResultsThirty-one participants (mean age: 23.2 ± 5.3 years) were recruited. The study group (n = 14) showed an improvement of -39.6 ± 25.8 % (p < 0.001) in CLDEQ-8 and 31.3 ± 14.6 points in GRCS (p < 0.001) after one month of DDCL use, while no changes in clinical tests were found. In the control group (n = 17), symptoms improved significantly after wearing the masked monthly CL (CLDEQ-8: -26.1 ± 31.0 %, p = 0.03; GRCS: 14.9 ± 17.0, p = 0.002), however a worsening in bulbar (26.5 ± 40.0 %; p = 0.02) and limbal hyperaemia (21.6 ± 34.7 %, p = 0.02) and an improvement of -19.1 ± 37.0 % (p = 0.049) in LWE was found. When the control group was fitted with the DDCL, improvements in GRCS (20.5 ± 25.5, p = 0.02), NITBUT (37.9 ± 42.3 %, p = 0.002), and conjunctival staining (-47.1 ± 59.9 %, p = 0.005) were noted.ConclusionsRefitting symptomatic monthly CL wearers with Delefilcon A DDCL is effective in reducing symptoms related to CLD. However, clinicians and researchers must be aware of the existence of a placebo effect when assessing the effectiveness of any CL refitting.     

Eye care professionals’ perceptions of the benefits of daily disposable silicone hydrogel contact lenses

PurposeTo gain a better understanding of eye care professionals’ (ECPs) perceptions regarding the benefits of silicone hydrogel (SiH) daily disposable contact lenses (DDCL), particularly with respect to health, comfort and patient satisfaction.MethodsA survey was conducted with 300 ECPs in the United States, United Kingdom and Japan during November 2017. The survey comprised 34 statements relating to SiH DDCLs, to which the ECPs provided their level of agreement using a 6 point Likert scale. A minimum of 70% agreement was set to define majority agreement. Categories of statements included Health, Comfort, Patient Experience, and Standard of Care.ResultsECPs rated the highest levels of agreement to perceptions within the Patient Experiences and Health categories. The six statements receiving the highest ratings were “Silicone hydrogel 1 day lenses satisfy today’s patients’ demanding lifestyles” (93% agreement); “Silicone hydrogel 1 day lenses are the best choice to safeguard my patients’ eye health related to contact lens wear” (92%); “Silicone hydrogel 1 day lenses provide the best benefits to my patients” (92%); “Silicone hydrogel 1 day lenses provide better long term eye health for my patients than hydrogel 1 day lenses” (91%); “Silicone hydrogel is the healthiest lens material for my daily disposable patients” (90%); and “Silicone hydrogel 1 day lenses provide a better wearing experience for my patients than hydrogel 1 day lenses” (90%).ConclusionECPs perceive that SiH DDCLs offer long-term eye health and comfort for the patient and although the ECPs surveyed would not necessarily prescribe SiH DDCLs to all their patients, they would prescribe them to most of their patients. The results support the premise that while ECPs consider SiH 1 day contact lenses as the current “standard of care”; the principal barrier continues to be the perceived higher cost of these lenses.     

尼龙餐厨具在热氧条件下的老化行为研究

目的对尼龙餐厨具样品进行差示扫描量热(differential scanning calorimetry,DSC)原位热氧加速老化行为研究,分析老化温度和老化时间对样品熔点和热稳定性能的影响。方法采用傅立叶变换红外光谱法(Fourier transform infrared spectroscopy, FTIR)探究老化温度和老化时间与样品分子结构变化之间的关系。结果在模拟使用温度100～260℃范围内,随着DSC热氧老化温度的上升,样品的短期老化作用不明显。在模拟极限使用温度240℃条件下,样品的老化以氧化作用为主,且随热氧老化时间的延长,样品分子链的支化和断链程度加剧,同时伴随着交联现象,总体氧化稳定性变差。结论在极限使用温度240℃条件下,当热氧老化时间短于30min时,市售尼龙餐厨具具有良好的耐热氧稳定性,但若热氧老化时间在延长至60min以上时,其内在结构可能因热氧老化作用发生变化且产生酮等氧化产物,存在安全风险。     

高温水直埋保温管道覆土后预热的应力计算

论述了热水直埋预制保温管道覆土后预热安装的管道应力计算方法。在设计和应用过程中需要注意的关键问题是保证管道接口处和一次性补偿器处的应力满足规范要求,确保管道的运行安全和使用寿命。     

线束支架成形、冲孔-切断工艺及模具设计

通过对后桥线束支架制件的工艺分析,介绍了不同方向多处加强筋的拉伸成形方式及冲孔-切断的冲压组合工艺,并确定相关工序的模具结构,最终分析了相应模具设计的要点。     

微波消解-电感耦合等离子体质谱法同时测定一次性纸杯中7种重金属元素的残留量

建立了同时测定一次性纸杯中Pb、Cr、Ni、As、Sb、Cd和Ba7种重金属元素的微波消解仪-电感耦合等离子体质谱仪法。样品以硝酸和双氧水为消解液,通过微波消解仪消解样品,采用动能歧视消除模式(kinetic energy discrimination,KED)和在线引入内标溶液进行检测。检测信号(CPS)与7种重金属元素含量之间呈现良好的线性关系,相关系数R~2均0.9997,样品回收率在85.0%~112.2%之间,相对标准偏差(RSD)小于6.46%。利用该方法分析了国家标准物质GBW10045中的7种重金属元素,所得结果与标准值基本一致。该方法具有灵敏快速和定量准确的特点,适用于一次性纸杯中7种痕量重金属元素的检测分析。     

Migration of formaldehyde and melamine from melaware and other amino resin tableware in real life service

ABSTRACT

The migration of formaldehyde and melamine monomers has been measured on 90 samples of plastic tableware in three different situations – new articles, already used articles and artificially aged articles – by using simulant, contact times and temperatures prescribed by Commission Regulation (EU) No. 10/2011. Formaldehyde was determined by ultraviolet spectroscopy analysis of the coloured complex obtained by reaction with chromotropic acid. Melamine was measured by an ultra high performance liquid chromatography method. Fourier Transformed – Infrared Analysis was applied to characterise the plastic. The results highlighted the presence of different amino resins based on formaldehyde-melamine, urea-formaldehyde or melamine-urea-formaldehyde with different migration behaviour. The migration of monomers was related to progressive degradation of the resins. Ageing studies demonstrated that the potential degradation of the resins and the consequent migration of the monomers may continue throughout the service life of the product. The specific migration limit (SML) of melamine was exceeded after ageing.     

从铬离子析出量的检测结果谈谈不锈钢食具的质量控制

对大量不锈钢食具及其原材料的铬离子析出量检测结果进行分析后,发现从原材料的选择到加工过程中力的变化、热处理和冷处理的工艺、表面粗糙度等均会影响不锈钢食具的铬离子析出量,本文提出在工艺上对奥氏体材料进行固溶、稳定化和去应力退火处理等以提高其耐腐蚀性能,在管理上加强对产品原材料、中间环节半成品及最终的成品进行严格的检测、记录、跟踪、监督,利用检测结果指导工艺改进,监督工艺成效,从而提高产品合格率,达到从产品源头开始控制产品质量的目的。     

功能型纸尿裤表层材料的开发及其性能研究

选用甲壳素、Lyocell和ES三种纤维为原料,采用水刺法进行固结,通过优化三种纤维的混用比例试验,对混合、梳理和水刺加固工艺进行合理配置,筛选出最佳工艺参数,试制成功一种外观均匀并布满椭圆形小孔的新材料。新材料作为功能型纸尿裤的表层材料,与现用材料进行了性能测试对比,其抗菌性、强力、透气性、吸收率和柔软性能明显提高。     

Applications of sample preparation techniques in the analysis of pesticides and PCBs in food

Pesticides and polychlorinated biphenyls (PCBs) are found in various parts of the environment in quite small concentrations, but they accumulate and thus become a threat to human health and life. A review is focused on the application of some popular techniques for sample preparation in analysis of these compounds in food. Even with the emergence of advanced techniques of final analysis, complex matrices, such as food, require extensive sample extraction and purification. Traditional sample preparation techniques are time consuming and require large amount of solvents, which are expensive, generate considerable waste, contaminate the sample and can enrich it for analytes. There have been many sample preparation techniques proposed to meet the requirements connected with the multiplicity of food. Optimal sample preparation can reduce analysis time, sources of error, enhance sensitivity and enable unequivocal identification and quantification. Sample extraction and purification techniques are discussed and their most recent applications in food analysis are provided. This review pointed out that sample preparation is the critical step.