复合助熔剂对煤灰熔融特性的影响研究

以高灰熔点煤AQ007为试验煤样,助熔剂5#矿渣和AND的添加量为考察因素,采用正交试验优化复合助熔剂的添加量,将AQ007煤的灰熔点降到1 400℃以下,以满足Shell气化炉的操作要求.最终确定助熔剂的最佳添加量为:5#矿渣为2.25%,ADN为1.5%.经过验证试验证实该复合助熔剂添加量可以使煤的灰熔点降到1 400℃以下.     

应用正交试验设计研究烟草中总氮测定的消化条件

采用L9（3^4）正交设计研究烟草中总氮测定的消化条件．结果表明：消化条件对烟样消化效应的极差是,称样量〉硫酸〉硫酸钾〉硫酸铜;称样量、硫酸和硫酸钾用量对烟样消化效果表现显著,硫酸铜用量不显著;选用400℃、180in、称样量0．3g、硫酸钾3．0g、硫酸5mL、硫酸铜0．1g为最佳消化条件．     

活性焦化学需氧量吸附值测定方法

通过实验确定活性焦化学需氧量(COD)吸附值测定方法中活性焦的称样量,据此建立针对活性焦性能指标的标准测定方法。实验中以邻苯二甲酸氢钾作为活性焦COD吸附值测定的标准物质,参照活性炭苯酚吸附值测定实验方法,进行活性焦COD吸附值测定的实验研究。对实验结果应用数据检验和回归分析,剔除异常值后,经t、F检验,得到活性焦COD吸附值与称样量之间的关联关系式。考虑满足COD吸附值测定数据受称样量影响变异系数小于5%,确定称样量为0.800~1.200 g,从而得到选定1.000 g作为测定方法中活性焦的合理称样量。     

复吹转炉炉渣无氟助熔剂的特性与应用

综合分析了国内转炉炉渣无氟助熔剂的研究和应用现状,从作用原理、转炉冶炼过程控制及经济性方面对MnO基和Al2O3基等无氟助熔剂进行了对比,并结合应用实际,提出了相应的无氟助熔剂的使用方法和注意事项。     

高氢金属钛中氧含量测定方法

对惰性熔融红外吸收法测定高氢钛样品中氧含量的分析方法进行了研究,确定了最佳分析参数。通过步进式升温模式将样品中的大部分氢提前释放出来,避免了在高温条件下甲烷的产生。确定高温段最佳分析功率为4. 8 k W;最佳样品称样量为0. 04～0. 08 g;助熔剂采用镍囊镍粒组合形式;氧最短分析时间为140 s,比较器水平设为1%。使用标样502-879建立单标样校准曲线,得到回归方程y=0. 7123 85x。通过对高氢钛样品的多次平行试验和加标回收试验对测定方法的可行性进行了分析,测定方法的相对标准偏差分别为2. 57%,加标回收率在95%～107%,表明该测定方法可以准确测定高氢钛样品中的氧含量。     

助熔剂对Ca_(0.99)(WO_4)_(0.5)(MoO_4)_(0.5):0.01Eu~(3+)的显微结构和荧光性能的影响

分别以Na Cl、KCl、Li2CO3、化学计量比为1:1的(KCl+Na Cl)为助熔剂,采用熔盐法制备了Ca0.99(WO4)0.5(Mo O4)0.5:0.01Eu3+红色荧光粉。利用扫描电子显微镜和荧光分光光度计分析不同类型的助熔剂对Ca0.99(WO4)0.5(Mo O4)0.5:0.01Eu3+荧光粉的颗粒形貌和荧光性能的影响,以及复合助熔剂(KCl+Na Cl)的含量变化对荧光粉的颗粒形貌和荧光性能的影响。结果表明:Na Cl、KCl、Li2CO3分别作为助熔剂时,荧光粉荧光强度增幅程度小,而(KCl+Na Cl)作为助熔剂,荧光粉的发光强度增幅程度大。当(KCl+Na Cl)复合助熔剂含量为1.5 g,粉体的荧光强度较大,颗粒分散性较好,粒度比较均匀。     

燃烧-碘量法测定钢铁中硫含量的实验研究

燃烧一碘量法是测定钢铁中硫含量的常用方法之一，用此法测定时炉温、助熔剂、氧气流量及适当的预热时间、淀粉水溶液的配制和使用等都对测定结果有很大的影响。本通过大量实验，找出了最佳的测定条件。     

碱土金属氧化物复合代替氧化铅研制无铅釉上彩熔剂

以碱-硼-硅系统为基础,加入碱土金属氧化物复合助熔剂,研制无铅釉上彩熔剂。其彩烤温度为720~780℃,利于色剂呈色,光泽度好,耐酸性强,各种性能达到了铅熔剂的效果。     

熔融制样XRF测定铜冶炼厂原料矿中主次成分

采用熔融制样技术,使用专用熔剂(过氧化钡、硝酸钠、四硼酸锂)对铜冶炼厂的入厂原料中铜、硫、铁、硅、钙、镁、铝、锌、砷等9种元素进行测定。通过实验确定最佳熔融条件为:试样与熔剂稀释比为1:30,预氧化温度为750℃;15分钟,熔融温度为1050℃;10分钟,200g/l溴化锂作为脱模剂。对用国家标准合成的样品进行分析,测定值与认定值相一致。对5个不同的原料矿样进行测定,与化学对标较好。分析结果精确度和正确度能够满足一般铜矿的分析要求。试验结果表明本方法快速,准确可靠。     

科尔沁沙地土壤微生物量碳的测定分析

通过对科尔沁沙地不同类型生物结皮土壤微生物量碳的测定分析,表明:土壤微生物量碳随土壤深度的增加而减少。有结皮的沙地微生物量碳含量较高。不同类型结皮中土壤微生物量碳关系不同。这对于研究本地区的环境保护、水土保持以及防风固沙等方面意义重大。     

Sexual victimization and adolescent weight regulation practices: a test across three community based samples

OBJECTIVE: This study had four objectives: 1) to examine the association between sexual victimization and weight regulation across three samples of adolescent girls, 2) to assess whether sexual victimization is associated with more extreme forms of weight regulation in girls, 3) to discern whether sexual victimization has implications for the use of multiple forms of weight regulation, and 4) to address the role of physical victimization in explaining these relationships. METHOD: Data from three separate samples of 9th-12th graders were used to test these hypotheses. Girls from the upper Midwest responded to survey questions related to victimization and weight regulation in a largely urban sample (N = 2,086), a rural sample (N = 2,629), and a statewide sample (N = 966). RESULTS: Logistic regression revealed that sexual victimization was consistently associated with weight regulation in adolescent girls, independent of the effects of physical victimization. In the urban sample, being sexually victimized was associated with an increase in the probability of purging by 18% relative to not being sexually victimized. Sexual victimization was associated more strongly with extreme forms of weight regulation and significantly discriminated whether girls would choose multiple weight regulation forms. CONCLUSIONS: Sexual victimization contributes unique variance to the probability that girls will practice weight regulation techniques. Data from three independent samples confirms that being violated sexually places girls at risk for various health compromising eating behaviors.     

On the utilization of sample weights in latent variable models

The purpose of this article is to examine the use of sample weights in the latent variable modeling context. A sample weight is the inverse of the probability that the unit in question was sampled and is used to obtain unbiased estimates of population parameters when units have unequal probabilities of inclusion in a sample. Although sample weights are discussed at length in survey research literature, virtually no discussion of sample weights can be found in the latent variable modeling literature. This article examines sample weights in latent variable models applied to the case where a simple random sample is drawn from a population containing a mixture of strata. A bootstrap simulation study is used to compare raw and normalized sample weights to conditions where weights are ignored. The results show that ignoring weights can lead to serious bias in latent variable model parameters and that this bias is mitigated by the incorporation of sample weights. Standard errors appear to be underestimated when sample weights are applied. Results on goodness‐of‐fit statistics demonstrate the advantages of utilizing sample weights.     

A Regularized GLS for Structural Equation Modeling

Ill conditioning of covariance and weight matrices used in structural equation modeling (SEM) is a possible source of inadequate performance of SEM statistics in nonasymptotic samples. A maximum a posteriori (MAP) covariance matrix is proposed for weight matrix regularization in normal theory generalized least squares (GLS) estimation. Maximum likelihood (ML), GLS, and regularized GLS test statistics (RGLS and rGLS) are studied by simulation in a 15-variable, 3-factor model with 15 levels of sample size varying from 60 to 100,000. A key result showed that in terms of nominal rejection rates, RGLS outperformed ML at all sample sizes below 500, and GLS at most sample sizes below 500. In larger samples, their performance was equivalent. The second regularization methodology (rGLS) performed well asymptotically, but poorly in small samples. Regularization in SEM deserves further study.     

Pathsways to school achievement in very preterm and full term children

Individual differences in academic success were investigated in a geographically defined whole-population sample of very preterm children with a gestational age of less than 32 weeks or a birth weight of less than 1500 gm. The sample consisted of 264 very preterm children (75.6% of German-speaking survivors) and 264 controls matched for gender, socioeconomic status, marital status and age of mother, who were studied from birth. The present analyses focused on the impact of cognitive skills assessed at ages 6 and 8 on academic success at the age 13. IQ scores, prereading skills, reading, spelling, and math performance assessed during the last kindergarten year and again at the end of Grade 2 were used as predictors of academic success in early adolescence. Differences between very pretern children and controls in cognitive abilities already observed in earlier assessments remained stable over time, with controls on average performing more than half a standard deviation above the level of preterm children. Preterm children also performed poorer on the literacy measures and indicators of math performance. Multivariate and causal modeling revealed different prediction patterns for the two groups. Whereas IQ was particularly important for the prediction of academic success in the pre-term sample, general IQ was less relevant for the prediction of academic success in the control group. When subgroups of at-risk children were formed according to birth weight categories, we found that school problems were most pronounced for children with extremely low birth weight (1000 gm and less).     

皖西白鹅内脏器官正常值的测定

本试验测量了20只成年皖西白鹅(公母各10只)的内脏器官,进行新鲜标本观察测量,同时比较公母鹅之间的差异。结果表明成年皖西白鹅公鹅的体重(4.98±0.60千克)和内脏器官的正常值范围较母鹅(体重4.78±0.75千克)高。     

柠檬蜡伞多糖的提取工艺研究

以柠檬蜡伞为试验材料,对其多糖的水浴法提取工艺进行了研究.在单因素试验的基础上,通过L（934）正交试验,确定柠檬蜡伞多糖的最佳提取条件为：液料比40∶1 mL/g、提取温度85℃、提取时间90 min,提取2次;在此条件下,多糖含量达4.412 g/100 g.试验结果可为柠檬蜡伞多糖类生物活性成分的进一步研究提供科学依据.     

采用电化学方法测量镀铬板表面金属铬和氧化铬的研究

利用电化学技术,以试样为阳极,白金为阴极,进行电解,根据试样同参比电极之间的电位差随时间变化的曲线得出溶解反应的终点,从而求出铬、氧化铬溶解所需的电量,根据法拉第定律计算出镀层的重量;根据电解法的校准系数K得到镀铬板的氧化铬。通过实际生产试样进行电解法与化学法的比对,检测精度满足生产要求。     

基于LabVIEW的动态称重系统的设计

为测量单托辊传送带在传输状态下固体散料的动态重量,采用称重传感器连续采样计量区段传输带托辊所受到的压力,用电涡流传感器测量放大后的辊轴瞬时速度,将采集的两路电压信号调理后,用测速法计算物料的瞬时重量和累积重量。动态称重系统采用虚拟仪器技术完成信号的采集和调理,上位机采用LabVIEW软件实现计算和显示,原理简单,精度高,易实现,具有较高的实用性。     

县城小学生肥胖发生率及其对肺功能的影晌

目的：掌握上高县小学生的肥胖发生情况,为防控小学生原发性肥胖提供依据。方法：制定纳入排除研究对象的标准,随机抽取上高县实验小学的学生,调查其肥胖状况并分析其肺活量、肺活量指数等指标。结果：共获得调查对象645名小学生。超重和肥胖总检出率分别为4.3％和2.0％,男生、女生超重、肥胖和超重肥胖合计的检出率分别为6.2％和2.1％、2.8％和1.0％、4.3％和2.0％。超重、肥胖小学生的肺活量均大于正常体重小学生,但肺活量指数前者均低于后者。结论：县城小学生尤其是男生的肥胖问题已较严重,应加强预防控制,以保障和促进其心肺功能的健康发育。