Comparison of the triangle and a self-defined two alternative forced choice test

The triangle test and the 2-AFC test or paired comparison are commonly used discrimination tests. The 2-AFC is statistically more powerful than the triangle test, but can only be used when the quality of the difference is known (e.g. one sample has added sucrose and is expected to be sweeter). By allowing subjects to define their own criteria for use in the 2-AFC, the procedure might be used when the sensory difference between two samples is not known or easily defined, as is possible during a warm-up protocol. The research reported here investigated a modification of the sometimes extensive warm-up procedure but limited the number of samplings of the preview samples. This modified procedure we describe as a self-defined 2-AFC (SD-2-AFC). This method was compared to the triangle and conventional 2-AFC using four food systems, differing in the magnitude and quality of sensory differences. The AFC tests (including the SD-2-AFC) performed better than the triangle on a statistical basis. However, in some cases the SD-2-AFC produced lower d-prime values indicating lower absolute levels of sensory differentiation. Correlates of poorer discrimination with the SD-2-AFC included miss-identification of the critical attribute (as determined by majority response) or reversal of the direction of the difference during the inspection phase. Results were interpreted in terms of Thurstonian models. No advantage of adding a preview to the triangle or 2-AFC was observed. The overall statistical advantage of the SD-2-AFC suggests it should be considered as an alternative to the triangle test.     

On-board generation of a highly volatile starting fuel to reduce automobile cold-start emissions

The on-board distillation system (OBDS) was developed to extract, from gasoline, a high-volatility fuel for exclusive use during the starting and warm-up periods. The use of OBDS distillate fuel results in much improved mixture preparation, allowing combinations of air/fuel ratio and ignition timing that are not possible with gasoline, even with a fully warm engine. The volatility of the distillate is a function of the parent fuel volatility; however, the variability in distillate quality can be diminished via manipulation of the OBDS operating conditions. Thus, it is possible to develop aggressive starting calibrations that are relatively immune to variations in pump gasoline volatility. The key benefits provided bythe OBDS fuel relative to standard gasoline were found to be (1) improved mixture preparation allowing a 70% reduction of cranking fuel requirements, elimination of air-fuel mixture enrichment during the warm-up period, and significant extension of warm-up ignition timing retard; (2) a 57% decrease in catalyst light-off time, (3) emissions reductions over the FTP drive cycle of 81% for regulated hydrocarbons (NMOG); (4) emissions index (NMOG) approaching that of SULEV/PZEV vehicles; and (5) an apparent 1% increase in fuel economy over the FTP drive cycle.     

Establishing thermal comfort: characterization of selected performance and physical properties of fabrics used in hospital operating room uniforms

The purpose of this research was to characterize selected thermal properties of clothing fabrics available to operating room (OR) workers at the University of Alberta Hospital and to relate the thermal properties to fabric structural characteristics. In this study, we measured the thermal resistance and air permeability of fabrics obtained from surgical gowns, scrubs and warm-up jackets currently in use in ORs in a specific hospital. The results showed that the fabrics from which the surgical gowns were made provide the highest thermal insulation with lowest air permeability, while the warm-up jackets’ fabrics had the greatest air permeability with low thermal insulation values. The clothing options available to workers in the OR fall well below the predicted clothing insulation values for thermal comfort. For workers in the OR, such as anaesthesiologists, who are predominantly sedentary throughout their work shift, the lack of thermally insulating clothing options has consequences for their overall thermal comfort. This study comprises part of a larger ongoing study investigating improving the OR workers thermal comfort through clothing.     

鲜奇可力提取方法研究

该文报道对鲜奇可力有效成分提取工艺进行优化实验。采用L9(34)正交实验分析法,得出最 佳工艺条件为:蒸汽加热温度125℃、加热60 min和提取时间50 min,为鲜奇可力加工提供一条极其 经济简捷途径。     

蒸煮锅内温差DMC-PID串级解耦控制

在置换蒸煮制浆过程中,蒸煮锅内温差过大会产生不均匀蒸煮现象,影响最终的蒸煮质量。针对蒸煮锅顶层流量与底层流量存在强耦合关系、蒸煮锅内温差大时滞特点、温差控制要求实时性,设计了DMC-PID串级解耦控制系统,通过流量-温差串级控制系统来实现对温差的控制。通过Matlab仿真表明,DMC-PID串级解耦控制系统具有更好的动态性能和鲁棒性,其控制效果明显优于单回路控制系统。     

热处理工艺解决车床尾座磨损问题的研究

现有某车间车床CA6140尾座体底面上的凹形导轨槽与尾座垫板上的凸形导轨配合部位锥面磨损,间隙过大,导致加工精度下降。尾座材料为灰铸铁,本文以HT200为试验材料,通过分别采用高频淬火处理与预热后再淬火处理来探讨对其磨损性能的影响,得出结论两种处理均能提高灰铸铁的耐磨性能,而后者对灰铸铁耐磨性能的提高更为显著。     

酱油香料制备的一种新方法

以混合还原糖和复合氨基酸为主要原料经美拉德反应制得酱油香料的基料,再经过调配可直接用作酿造酱油的香料。实验室研究结果表明,美拉德反应的最佳反应条件是:复合氨基酸:混合还原糖为(4～5.5):1,反应温度为90～110℃(分段升温),微波下反应时间为15～25min,无微波辐照下120～180min,pH值为3.1～4.4.。在混合物溶剂下可制备得到酱色深、酱香气味浓郁、味道鲜美的反应型香料基料。制品经质量检测分析,结果显示用本法制得的酱油香料各项质量指标均符合GB2760-1996和GB18186-2000的要求。该香料基料经适当调制后的此香料应用到酿造酱油中,获得了较好的实验效果。     

Rain damaged wheat tester: An instrument for the rapid assessment of sprouted grain at silos

A small unit for the rapid assessment of sprouted grain in cereal samples has been developed. The technique is based on the use of a β-amylase-resistant α-amylase chromogenic starch substrate, and is therefore specific for α-amylase. Extraction time for α-amylase from the grain is 30 s using a blender. Incubation time with the substrate in the unit is 3 min. Results are expressed as the percentage of sprouted grain in the sample. The small size of the unit, and the rapid warm-up time, enable the unit to be readily moved between grain receival points. The unit is electrically mains operated.     

Factors affecting the quality of a novel fresh-cut sweet cherry product

The primary objective of this work was to evaluate whether sweet cherries could make an acceptable fresh-cut fruit product. The concept was to develop a cherry product cut such that the pit and associated tissue from stem bowl to the nose of the fruit were removed in a single cutting operation, leaving a cherry with a ‘hole’ which could be filled with various foodstuffs (much like a pitted olive). Secondary objectives were to determine if the design of the cutting tube, storage at low temperature before cutting or preharvest treatment with gibberellic acid (GA: used to improve firmness in commercial production) could influence the quality of packaged fresh-cut sweet cherries. Most cultivars of sweet cherries tested appeared to be suitable for cutting, and quality was not impacted significantly if GA was used on the fruit prior to harvest. Low temperature of the fruit at the time of cutting appeared to lead to greater deterioration than warm temperatures and so perhaps a warm-up time is required if the fruit are held in cold storage before cutting. Finally, the design of the cutting tube was of great importance with a scalloped-edge resulting in a lower cutting force, and hence less injury and better quality, than a straight-edge design.     

葡萄糖还原重铬酸盐影响因素变化规律的研究

利用正交实验的极差分析法，对葡萄糖还原重铬酸盐制铬液影响因素的变化规律进行了研究。结果表明铬鞣液碱度除了与硫酸用量有关外，糖的用量影响也很大。糖量是影响氧化剂转化率的决定性因素，其它因素硫酸、温度和水量对转化率的影响，随反应进行而变化。椐温度对反应转化率的影响制定了制备铬液的升温曲线，此曲线对实际生产具有一定的指导作用。     

Effect of method of analysis on iron content of beef from advanced meat recovery systems

A field survey was conducted by the USDA, Food Safety Inspection Service (FSIS) to provide analytical data on meat obtained from beef cervical vertebrae processed by advanced meat recovery (AMR) systems. As a result, an added iron performance standard was proposed to limit the amount of marrow in AMR products. The performance standard was based on iron content of hand boned lean compared to AMR lean. Iron content was determined by a hydrochloric wet ash digestion method. The same samples were then analyzed using dry ash digestion. The objectives of the study were to determine differences in iron content of the survey samples due to the digestion method and the impact of this difference on the added iron performance standard. Iron values by the dry ash method were approximately double those of the wet ash method. The difference was a result of incomplete volatilization of the organic matrix by hydrochloric acid in the wet ash procedure. The performance standards developed from the wet and dry ash methods were 1.8 and 3.2 mg added iron 100⁻¹ g, respectively. Added iron levels from the dry ash method greater than 3.2 mg 100⁻¹ g were present in 60% of the AMR lean indicating that some marrow was present or that factors other than amount of iron in hand boned lean should be considered before a performance standard is established.     

温度控制对微波萃取叶黄素酯的影响

探索温度控制对微波辅助萃取叶黄素酯萃取率的影响。首先测定不同输出功率对萃取溶媒升温的影响,然后以万寿菊干花颗粒为样品,探讨升温功率、萃取时间和萃取温度对萃取率的影响,并比较相同温度条件下微波萃取与溶剂法的萃取率。结果表明：分子中含有O－H键的溶媒升温较快;升温功率的变化对萃取率的影响有限。萃取时间的延长可导致萃取率下降;在1600W、20min和分别为50、50、40℃条件下,正己烷、乙酸乙酯和四氢呋喃萃取率分别为83%～95.23%、81.44%～96.59%和91.72%～94.40%。在相同温度条件下,微波萃取可有效地提高叶黄素酯的萃取率。     

烟叶原料对卷烟主流烟气7项有害成分释放量的影响研究

为了解烟叶原料对卷烟主流烟气中7种有害成分的影响,选取了产地、烤房、品种、土壤、烟叶部位作为因素对237个初烤烟叶样品中主流烟气7项有害成分指标进行了多因素方差分析,结果表明:对于本研究所选取的烟叶样品来说,对7种烟气有害成分释放量指标有显著性影响的重要因素是产地、烟叶部位、品种三个因素,其中产地为关键因素,它在7个指标上均表现显著差异,产地7个指标显著方差分量比例为64.00%;烟叶部位也为关键因素,它在6个指标上表现显著差异,烟叶部位6个指标显著方差分量比例为26.51%。品种为重要因素。而烤房、土壤对7个烟气释放量指标影响不显著。      

婴幼儿配方食品中维生素D标准检验方法等效性评价研究

目的评价研究婴幼儿配方食品中维生素D标准检验方法等效性。方法采用成对方法比较,通过实验室间比对研究,结合方法性能评价与运用合适统计工具对标准检验方法的分析结果进行定性定量评价。结果综合对方法性能与检测结果的评价,成对方法之间无显著性差异,在等效边界15%时方法等效,检测均值的差异均低于可接受临界差异。结论3对成对方法是等效的。方法等效性评价接受标准必须结合企业内部质量控制或监管层面实际的需求而定。     

超导量点—免疫荧光法快速测定粮食中黄曲霉毒素B1的方法验证

以超导量点为荧光探针,建立了一种超导量点-免疫荧光快速测定粮食中黄曲霉毒素B1的方法。采用多种方式评价了该方法与高效液相色谱法及酶联免疫吸附法检测稻谷及玉米样品的结果一致性,以验证该方法的准确性,同时对该方法的重复性和台间差异进行了考察。结果表明,超导量点-免疫荧光法对稻谷和玉米等粮食样品的检测结果与高效液相色谱法和酶联免疫法一致,表明该方法准确可靠,同时该方法两台仪器间的检测结果无显著性差异,且重复性好。     

PERFORMANCE of HEAT RECOVERY SYSTEM FOR A SPRAY DRYER

A factorial experimental design was used to study the effect of exhaust heat recovery, air flow rate and outlet temperature on the energy consumption of a spray dryer. A commercial-scale cocurrent flow dryer with pressure atomization was used to dry 15 wt% sodium sulfate solutions. the inlet air to the dryer was preheated by using a shell-and-tube heat exchanger to recover energy from the exhaust air. Heat recovery reduced the energy consumption of the dryer by 12–28%, with the largest reduction occurring at the high levels of air flow rate (13,000 kg/h) and outlet temperature (104°C). the energy consumption of the dryer was lowest when heat was recovered at the low air flow rate (6500 kg/h) and low outlet temperature (82°C). No problems were encountered with fouling or cleaning of the heat exchanger. the total pressure drop across the heat exchanger varied from 0.05–0.2 kPa depending on the air flow rate. This additional flow restriction resulted in an estimated 8% decrease in air flow rate but had negligible effect on energy consumption. the warm-up time and the space required by the heat recovery unit were insignificant factors for this dryer. the payback period of the heat recovery system was estimated as 4.1–5.4 years with a rate of return of 21–28%.     

Sensory difference tests: Overdispersion and warm-up

For sensory difference tests, one way, but not the only way, of dealing with the problem of overdispersion is to use a beta-binomial analysis. Commonly, binomial statistical analyses are used for these methods and they assume that the sensitivity of the judges is uniform. However, judge sensitivity varies and this adds a problematical extra variance to the distribution. This is termed overdispersion and renders simple binomial analysis prone to Type I error. The distribution of sensitivity of the judges is described by a beta-distribution. The analysis, combining beta and binomial distributions, gives an index, gamma. This ranges from zero, for no overdispersion, to unity, for total overdispersion. A compact beta-distribution clustered around the mean of the binomial distribution, would add little extra variance and elicit minimum distortion of the binomial distribution, yielding a zero or near zero gamma value. A more scattered or even bimodal beta-distribution would have a substantial effect and yield a significant gamma value. One question that has been posed is whether some test methods are more prone to overdispersion than others. Yet, a consideration of the reasons for overdispersion would suggest that significant gamma values were more a result of obtaining a heterogenous sample of sensitive and insensitive judges by chance. To confirm this, ‘less sensitive’ and ‘more sensitive’ samples of judges performed 2-AFC and 3-AFC tests with resulting zero gamma values, indicating no overdispersion. However, when the less and more sensitive groups were combined, significant gamma values were obtained, indicating the presence of overdispersion. However, in a further experiment using 2-AFC tests, when the ‘less sensitive’ group had its sensitivity increased by a ‘warm-up’ procedure, combination with the ‘more sensitive’ group did not result in overdispersion.     

纳米TiO2抗紫外线整理棉织物的染色性能

 用不同结晶结构的纳米TiO2对棉织物进行抗紫外线整理,然后用红花红色素染色,并观察耐光色牢度。结果表明：经纳米TiO2抗紫外线整理的棉织物其K/S值小于整理前的棉织物;金红石型纳米TiO2整理棉织物的K/S值高,光老化时色差值变化较小,与整理前棉织物的色差值相近;随着聚乙二醇(PEG)分子质量的增大以及TiO2/PEG含量的增加,K/S值减小,光老化时色差值变化大。在CIE和孟塞尔(Munsell)表色系中,也表现出相同的染色性能。     

高分辨质谱库和特征组分诊断比值法快速筛查鉴别食品中非法添加黄芪

目的：建立了一种基于高分辨质谱库和特征组分诊断比值法筛查鉴别食品中非法添加黄芪的方法。方法：采用高效液相色谱-四极杆-飞行时间质谱仪构建黄芪4种特征组分高分辨质谱库进行初步筛查,结合特征组分诊断比值法,对不同产地和采摘时间的黄芪中药材模拟的配制酒、代用茶和饮料样品进行特征组分分析,以不同基质组间无显著性差异的特征组分峰面积诊断比值作为确证指标。结果：建立了黄芪4种特征组分高分辨质谱库,确定了黄芪中不同基质组间无显著性差异的1组特征组分峰面积诊断比值DR1 (毛蕊异黄酮苷/芒柄花苷),诊断比值非异常值范围分别1.86-2.71;并对实际样品配制酒、代用茶及饮料进行分析,1批次配制酒样品与黄芪4种特征组分高分辨质谱库匹配一致,且特征组分诊断比值DR1为1.98,在规定区间内,推断该配制酒样品中加入了黄芪中药材。结论：该方法准确、快捷、稳定性好,可快速鉴别食品中非法添加黄芪,为打击食品中非法添加黄芪违法行为提供技术支撑。     

紧密纺用胶辊的优选

紧密纺配件的使用是影响紧密纺纱线性能的一个重要因素。为了研究紧密纺用胶辊与普通环锭纺用胶辊的区别,并对紧密纺用胶辊的型号进行优化,选用不同型号的胶辊进行上车试纺,测试所纺纱线的性能,从而对紧密纺胶辊进行优选。