基于GUM法的风电叶片结构试验方法不确定度研究

针对风电叶片全尺寸结构试验方法,首先分析试验过程中所需测量物理量的不确定度因素来源;其次利用GUM法建立不确定度数学模型,然后评定各部分输入量的标准不确定度;最后分析得到叶片结构试验各测试物理量的合成标准不确定度和扩展不确定度,从而建立风电叶片试验不确定度的系统评价方法。

自适应MCM法和GUM法评价直接进样测汞法测定稻谷中总汞的不确定度比较研究

重金属汞污染是危害粮食安全的重要问题,直接进样测汞法的检测过程中需要对检测结果做好质量控制。检测结果需要识别实验过程中各环节对结果的影响大小。基于GB/T 27404—2008《实验室质量控制规范食品理化检测》附录F中对实验室开展新项目所需验证的各种项目:回收率、标准曲线、测定低限、精密度、准确度等。使用自适应蒙特卡洛法(adaptive Monte Carlo method,MCM)和测量不确定度表示指南方法(Guide to the expression of uncertainty in measurement,GUM)分别对直接进样测汞法开展不确定度评定。GUM法得到的不确定范围为(0.0193±0.0017)mg/kg(k=2);MCM法得到的不确定度置信区间(95%)为[0.0177,0.0211];使用MCM Alchimia软件对2种方法的不确定度概率密度拟合曲线,MCM法与GUM法评价结果一致性较好。分析不确定度评定过程中各不确定度贡献率,回收率和标准曲线拟合过程引入不确定度在检出限处引入的不确定度分量较大,建议在方法验证和不确定度评定中使用定量限作为加标回收率和标准曲线最小浓度点。

Alleviation of the plastic deformation of gel ink under strong stress through an esterification of xanthan gum reinforcing its double helix structure

As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ink.However,as the double-helix structure connected by hydrogen bonds cannot resist the mechanical environment of strong stress,XG shows poor shear resistance.In this study,a polymer gel with interpenetrating polymer network structure was prepared by esterifying XG,taking polystyrene maleic anhydride(SMA)as the modifier.In addition to retaining the excellent rheological properties of XG,the generated polymer gel also exhibited high shear resistance.The optimal addition amount of the esterification reaction modifier was determined as mXG:mSMA=5:3 according to the gel ink standard.With this amount,the viscosity of the modified xanthan gum(SXG)gel increased to 1578.8 mPa·s and 100.7 mPa·s at shear rates of 4 s1 and 383 s1,respectively,and the shear resistance increased more than 2 times compared to the unmodified one.It is because of the ester bond formed by esterification that the reaction strengthens the interaction between molecular segments,enabling the new gel to resist to strong mechanical stress.The new polymer gel studied in this paper and the proposed mechanism of action provide new insights for the development of high-end gel ink and also provide theoretical support for the study of rheological properties of non-Newtonian fluids.

Enhancement of the Antigenotoxic and Antioxidant Actions of Eugenol from Spice Clove and the Stabilizer Gum Arabic on Colorectal Carcinogenesis

Spices are defined as any aromatic condiment of plant origin used to alter the flavor and aroma of foods. Besides flavor and aroma, many spices have antioxidant activity, mainly related to the presence in cloves of phenolic compounds, such as flavonoids, terpenoids and eugenol. In turn, the most common uses of gum arabic are in the form of powder for addition to soft drink syrups, cuisine and baked goods, specifically to stabilize the texture of products, increase the viscosity of liquids and promote the leavening of baked products (e.g., cakes). Both eugenol, extracted from cloves, and gum arabic, extracted from the hardened sap of two species of the Acacia tree, are dietary constituents routinely consumed virtually throughout the world. Both of them are also widely used medicinally to inhibit oxidative stress and genotoxicity. The prevention arm of the study included groups: Ia, IIa, IIIa, Iva, V, VI, VII, VIII. Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the same period and for an additional 9 weeks, the animals received either water, 10% GA, EUG, or 10% GA + EUG by gavage. The treatment arm of the study included groups Ib, IIb, IIIb e IVb, IX, X, XI, XII). Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the subsequent 9 weeks, the animals received either water, 10% GA, EUG or 10% GA + EUG by gavage. The novelty of this study is the investigation of their use alone and together for the prevention and treatment of experimental colorectal carcinogenesis induced by dimethylhydrazine. Our results show that the combined use of 10% gum arabic and eugenol was effective, with antioxidant action in the colon, as well as reducing oxidative stress in all colon segments and preventing and treating genotoxicity in all colon segments. Furthermore, their joint administration reduced the number of aberrant crypts and the number of aberrant crypt foci (ACF) in the distal segment and entire colon, as well as the number of ACF with at least 5 crypts in the entire colon. Thus, our results also demonstrate the synergistic effects of 10% gum arabic together with eugenol (from cloves), with antioxidant, antigenotoxic and anticarcinogenic actions (prevention and treatment) at the doses and durations studied, in the colon of rats submitted to colorectal carcinogenesis induced by dimethylhydrazine.

GUM评定数字式气压计不确定度的适用性验证

为确保数字式气压计测量不确定度的可靠性,需对现有的测量不确定度表示指南(GUM)评定数字式气压计不确定度的方法进行适用性验证。本文根据国际标准ISO/IEC Guide 98-3:2008附件1给出的蒙特卡洛法(Monte Corlo Method,简称MCM)验证方案,以PTB220型数字式气压计为研究对象,分别采用自适应MCM对GUM方法进行不确定度的评定;将评定结果对比求偏差;根据偏差值是否超限来判定GUM方法适用性。结果表明:所采用的自适应MCM通过迭代增加试验次数,实时判断试验统计意义上的稳定,能有效确保评定结果的可靠性,且仅通过2×10^(4)样本量,计算出对应的评定结果。通过将GUM评定结果与其对比求偏差,分析得出GUM在进行数字式气压计的不确定度评定时偏离程度超过规定范围,说明GUM未能通过验证,即GUM可能不宜适用于该仪器不确定度的评定。

Effect of defatted flaxseed gum powder addition on the quality of sesame paste

The study explored the influence of defatted flaxseed gum powder(DFGP) on the stability and quality of sesame paste by measuring and analyzing its composition, color, texture, particle size, centrifugal oil separation rate,rheological properties, and microstructure. The results showed that the moisture and polysaccharide content of sesame paste was increased as the DFGP increased. Additionally, the hardness, gumminess, and chewiness of the sesame paste was improved, while the presence of particles with small particle size(1–100 μm) was decreased.The rate of oil precipitation was reduced by 28.99% when the amount of DFGP was 6%. The sesame paste samples exhibited pseudoplastic behavior, demonstrating shear thinning. As the shear rate increased, the apparent viscosity of sesame paste gradually decreased. Both the storage modulus(G’) and the loss modulus(G’’) increased as the shear frequency increased. The microstructure observation revealed that protein and oil were evenly distributed in the sesame paste system, and the addition of DFGP enhanced the bonding between oil and protein.This study can provide valuable references for high-quality sesame paste products in the food industry.

Effect of Gum Arabic from Acacia senegal var. kerensis as an Improver on the Rheological Properties of Wheat Flour Dough

Dough improvers are substances with functional characteristics used in baking industry to enhance dough properties. Currently, the baking industry is faced with increasing demand for natural ingredients owing to increasing consumer awareness, thus contributing to the rising demand for natural hydrocolloids. Gum Arabic from Acacia senegal var. kerensis is a natural gum exhibiting excellent water binding and emulsification capacity. However, very little is reported on how it affects the rheological properties of wheat dough. The aim of this study was therefore, to determine the rheological properties of wheat dough with partial additions of gum Arabic as an improver. Six treatments were analyzed comprising of: flour-gum blends prepared by adding gum Arabic to wheat flour at different levels (1%, 2% and 3%), plain wheat flour (negative control), commercial bread flour and commercial chapati flour (positive controls). The rheological properties were determined using Brabender Farinograph, Brabender Extensograph and Brabender Viscograph. Results showed that addition of gum Arabic significantly (p chapati. These findings support the need to utilize gum Arabic from Acacia senegal var. kerensis as a dough improver.

Physico-Chemical, and Sensory Properties of Mayonnaise Substitute Prepared from Chia Mucilage (Salvia hispanica L.) and Gum Arabic from Acacia senegal var. kerensis

Gum Arabic (GA) from Acacia senegal var. kerensis has been approved as an emulsifier, stabilizer, thickener, and encapsulator in food processing industry. Chia mucilage, on the other hand, has been approved to be used as a fat and egg yolk mimic. However, both chia mucilage and gum Arabic are underutilized locally in Kenya;thus, marginal reports have been published despite their potential to alter functional properties in food products. In this study, the potential use of chia mucilage and gum Arabic was evaluated in the development of an eggless fat-reduced mayonnaise (FRM). The mayonnaise substitute was prepared by replacing eggs and partially substituting sunflower oil with chia mucilage at 15%, 30%, 45%, and 60% levels and gum Arabic at 3% while reducing the oil levels to 15%, 30%, 45%, and 60%. The effect of different concentrations of oil and chia mucilage on the physicochemical properties, for example, pH, emulsion stability, moisture content, protein, carbohydrate, fats, calories, ash, and titratable acidity using AOAC methods and sensory properties for both consumer acceptability and quantitative descriptive analysis of mayonnaise were evaluated and compared to the control with eggs and 75% sunflower oil. The results indicated that all fat-reduced mayonnaises had significantly lower energy to 493 kcal/100g and 20% fat content but higher water content of 0.74 than the control with 784 Kcal/100g calories, 77% fat and 0.39 moisture. These differences increased with increasing substitution levels of chia mucilage, as impacted on pH, carbohydrate, and protein. There was no significant difference between ash content for both fat-reduced mayonnaise and control. Sensory evaluation demonstrated that mayonnaises substituted with chia seeds mucilage and gum Arabic were accepted. All the parameters are positively correlated to overall acceptability, with flavor having the strongest correlation of r = 0.78. Loadings from principal component analysis (PCA) of 16 sensory attributes of mayonnaise showed that approximately over 66% of the variations in sensory attributes were explained by the first six principal components. This study shows good potential for chia mucilage and gum Arabic to be used as fat and egg mimetics and stabilizers, respectively, in mayonnaise with functional properties.

Continuous Gum Chewing Exercise Improves Perioral Muscle Strength

Objective: The purpose of this study was to examine the effects of continuous gum chewing exercise on perioral muscle strength. Methods: Thirty healthy adults (24.1 ± 2.0 years) with normal occlusion performed gum chewing exercise 3 times daily for 3 months. Each exercise session lasted 5 min and involved alternating of chewing 10 times using the left molars and then 10 times using the right molars, with the mouth closed. The effect of the exercise on oral function was evaluated by measuring tongue pressure (TP), cheek pressure (CP), and labial closure strength (LCS) immediately before starting exercise, at 2 weeks and 1, 2, and 3 months after starting exercise, and at 3 months after cessation of exercise. Changes in TP, CP, and LCS according to sex and duration of exercise were analyzed by repeated two-way ANOVA. Results: Measurements for all muscles were significantly greater in men than in women at all time points. After starting exercise, TP was markedly increased at 2 months in men and women, and both CP and LCS were markedly increased at 2 weeks in men and at 1 month in women. These effects persisted for 3 months. Three months after cessation of exercise, TP, CP, and LCS tended to decrease, but were not significantly attenuated as compared with 3 months after beginning of exercise in either sex. Conclusion: The results of this study revealed that gum chewing exercise contributed to an improvement in perioral muscle strength, and that this effect was maintained for at least 3 months after discontinuation of exercise.

GUM与基于观测方程的测量不确定度评估

比较了GUM系列文件与贝叶斯方法评估不确定度的过程,说明GUM是以测量方程为基础的前向分析方法,而贝叶斯分析是以观测方程为基础、以数据分析为主的一种后向不确定度评估方法。运用概率模型的描述方法对上述两种分析过程进行了分析与比较,说明了两种方法在线性测量模型的条件下,不考虑被测量先验分布时两种结果基本一致,对于非线性的测量模型,GUM S1得到的结果与一定先验分布条件下的贝叶斯分析的结果也基本一致。最后通过实例说明了该结论。

GUM法与蒙特卡洛法在IFCC37℃肌酸激酶催化活性水平参考测量程序不确定度评定中的应用

目的用测量不确定度表示指南(GUM)与蒙特卡洛法(MCM)评定本室条件下国际临床化学与检验医学联合会(IFCC)37℃肌酸激酶(CK)参考测量程序的不确定度,比较两种评定结果并尝试寻找适用的酶学参考测量不确定度评定模式。方法按照IFCC参考方法测定样品RELA2012KSA中CK活性水平,寻找测定过程中各不确定度来源,确定本室酶学参考测量模型。用GUM法与MCM法评定3次测量结果的不确定度,并以自适应MCM法对GUM法结果进行验证。结果本室实验条件下,CK活性测定不确定度来源主要有修正后的反应速率、总体积比、样品复溶体积、比色皿光径、摩尔吸光系数、反应温度与pH值及监测波长的偏离等。CK单次测定GUM法不确定度评定结果为(260.0±12.2)U/L,相对扩展不确定度为4.7%,3次测定结果的95%概率对称包含区间分别为(247.829 5,272.094 7)U/L、(246.938 8,270.923 6)U/L、(246.495 1,269.857 5)U/L,均值的不确定度评定结果为(259.0±7.0)U/L,相对扩展不确定度为2.7%。3次CK测定MCM法不确定度评定结果为输出量估计值,分别为260.0、259.0、258.2 U/L,95%概率对称包含区间分别为(248.753 2,271.535 7)U/L、(247.746 9,270.418 0)U/L、(247.303 9,269.330 8)U/L。用MCM法验证GUM法包含区间,3组绝对偏差dlow与dhigh值均大于数值容差0.05,GUM法结果未通过MCM法验证。结论 MCM法结果更为准确,可用于结果报告。GUM法结果经MCM法验证其质量后,可用于发现各不确定度来源对参考测量质量的影响,提高实验室质量改进效率。联合应用GUM法与MCM法进行不确定度评定可作为酶学参考测量不确定度评定方案的一种选择。

采用MCM对GUM法测量不确定度评定的验证方法研究

目前不确定度评定的基本方法是GUM法,GUM法在一定的条件下是可以有效应用的,但在模型复杂的情况下,却不容易直接确定其是否满足所有的应用条件。由于蒙特卡罗法(MCM)的有效性范围大于GUM法的有效性范围,因此可利用合适的软件,应用MCM对GUM法测量不确定度的评定结果进行验证。建议此时分别应用GUM法和MCM法,并对结果进行比较。如果结果较满意,则表明GUM法可应用于此类场合;否则,应考虑使用MCM或其它适当的替代方法。通过质量计量的实例,介绍了采用MCM对GUM法进行验证的两种方法。

GUM S1与基于贝叶斯方法的不确定度评估比较

论述了GUM S1与基于贝叶斯方法的不确定度评估,解析说明了GUM S1是一种选定参数且在特定先验信息下的贝叶斯方法。在一定的先验条件下对于线性系统,GUM S1与贝叶斯评估方法的结果是一致的;但对于非线性测量模型,两者的结果通常都不一样,其原因在于选择了不同的参数组以及先验信息的选取。通过两个测量模型的实例说明:对于线性系统,两种方法都可以使用;但对于非线性测量模型,且对被测量无先验信息时采用GUM S1所推荐方法能得到较为可靠的结果。在实际计量工作中若对被测量有了解,则可以采用贝叶斯分析方法。

Hydrothermal synthesis of silver nanoparticles in Arabic gum aqueous solutions

Finely divided silver nanoparticles were synthesized via the hydrothermal method. Arabic gum （AG） was used as both the reductant and steric stabilizer without any other surfactant. By adjusting the reaction temperature, mass ratio of AG to AgNO3, and reaction time, silver nanoparticles with different morphological characteristics could be obtained. The products were characterized by UV-Vis, FTIR, TEM, SEM, and XRD measurements. It was found that temperature and AG played an important role in the synthesis of mono-disperse silver nanoparticles. Well dispersed and quasispherical silver nanoparticles were obtained under the optimal synthesis conditions of 10 mmol/L AgNO3, m（AG）/m（AgN03）= l：1, 160 ℃ and 3 h.

GUM与MCM评定雨量传感器不确定度对比研究

以SL3-1型双翻斗雨量传感器的校准结果为例,开展评定雨量传感器不确定度对比研究。首先,对雨量传感器结构、工作原理以及试验方案进行分析。然后,分别采用《测量不确定性的表达指南》(GUM)和蒙特卡洛法(MCM)对雨量传感器误差的测量不确定度进行分析与评定,发现MCM比GUM具有更完整的理论依据,能有效地简化不确定度的评定流程等。最后,根据《用蒙特卡洛法评定测量不确定度》方法,用MCM对GUM进行适用性验证,发现GUM不适合翻斗式雨量传感器误差的测量不确定度的评定。研究结果显示,评定翻斗式雨量传感器误差的测量不确定度时,采用MCM更合适,可提高雨量传感器测量结果的可信程度。该研究有效突破以往研究中仅依靠GUM评定雨量传感器不确定度,导致结果可靠性不高的现状。该研究对于观测数据的合理应用、仪器的改进与研发等方面有着重要的理论和应用价值。

皮托管测量风速时GUM评定不确定度的偏差修正

针对不确定度表示指南法(GUM)进行皮托管测量风速值的不确定度评定时,测量结果存在偏差的现状,为确认该方法的适用性,并获取其偏差的修正值,首先采用GUM和蒙特卡洛法(MCM)对皮托管测量风速值的不确定度进行评定;然后,通过JCGM 101:2008 GUM supplement 1给出的方法,对GUM的适用性进行验证;最后,将GUM与MCM获取的风速测量结果进行对比。结果表明,GUM方法依然适用于皮托管进行风速测量时的不确定度的评定;GUM评定的结果标准不确定度产生了负偏差,其相对于实测风速值的偏差率为-0. 611 8×10-5,对应的修正值为'0. 611 8×10-5×实测风速值',由于该值相对于实测风速值较小,因此,在应用时可根据实际情况,决定是否对其进行修正。

蒙特卡洛法与GUM评定测量不确定度对比分析

为了分析蒙特卡洛法(MCM)和GUM在评定测量不确定度时的应用情况,首先介绍了GUM和MCM评定测量不确定度时的具体步骤,以评定空盒气压表和气温传感器的测量不确定度为实例,通过仿真实验得出,相比GUM而言,MCM采用真实的模拟策略,通过计算机程序来实现输出量概率分布的解算,其适用范围更广、可操作性更强、可信度更高;当输入量均为正态分布时,GUM和MCM评定的结果一致性较好;当输入量为非正态分布时,会导致GUM评定结果趋于保守;当输入量的分布区间不对称时,会导致GUM评定结果的区间发生偏离。

基于GUM法和控制图法评定烟草中淀粉含量测定的不确定度

本研究分别基于《测量不确定度表示指南》规定的方法(GUM法)和控制图法对连续流动法测量烟草中淀粉含量的不确定度进行评定。结果表明:取扩展因子k=2,置信概率为95%,GUM法和控制图法评定烟草中淀粉含量分别为4.23%±0.10%和4.26%±0.54%,控制图法评定结果较大。采用GUM法建立不确定度模型,不确定度由样品质量测定、含水率测定、前处理稀释定容过程、浓度测定、测定重复性组成,其中测定重复性是最大不确定度分量。综合2种方法,推荐已确定不确定度主要来源的实验室采用控制图法进行实验室质控水平的长期评定。

野油菜黄单胞菌中gumD基因的过表达对产黄原胶的影响

目的在野油菜黄单胞菌58(Xc58)中过量表达产胶基因gumD,提高黄原胶发酵产量和质量。方法通过PCR扩增、重组质粒构建、三亲本接合等方法,将重组质粒pBBR-gumD转入原始菌Xc58。结果工程菌与原始菌相比,黄原胶产量提高11.19%,黏度提高6.31%,重均分子质量提高20.21%,乙酰基含量提高77.07%,丙酮酸含量下降6.34%。结论改造后的菌株的黄原胶发酵产量和质量都较原始菌株有所提高。

基于蒙特卡罗法与GUM法的直线度测量不确定度评定

由于形位误差测量的复杂性和测量结果评定的多样性,导致在实际测量结果中形位误差的不确定度评定成了难题。通过GUM法和蒙特卡罗法对直线度的测量不确定度进行评定。首先,根据最小二乘法得到直线度的误差模型;然后采用GUM方法对测量结果进行不确定度评定,采用蒙特卡罗仿真方法对测量值进行模拟仿真,从而得到直线度误差的不确定度;设置实验对比,通过数据分析验证了蒙特卡罗方法评定的可行性,为形位误差测量结果不确定度评定提供了更加简便的方法。