汽化处理琥珀的宝石学特征

对半透明-半蜜蜡状金绞蜜、透明金珀在压炉中进行汽化处理实验,对比处理前后样品的宝石学特征,总结出汽化处理琥珀("水煮蜜")的主要鉴别特征:(1)经汽化处理的琥珀原料可在其天然风化皮内再生一层厚度不等且颜色为黄白色或黄绿色的"水煮皮",同时原料表面局部会出现大小不等的气孔及黑色、黄白色结痂状皮壳;(2)汽化处理琥珀("水煮蜜")成品表面可残留白色的圆形"水煮斑";(3)汽化处理琥珀("水煮蜜")的气液二相包裹体丰富,气泡多呈细小扁平状,且流纹模糊、不流畅;(4)扫描电子显微镜观察经汽化处理琥珀("水煮蜜"),发现其气泡分布密集,大小不均,并伴有微小应力纹。对于汽化处理琥珀("水煮蜜")的鉴别应寻找综合证据,其中"水煮皮""水煮斑"和细小扁平状气泡群具有重要意义。     

不同产地琥珀有机元素组成及变化规律研究

采用Elementar vario PYRO cube型元素分析仪(EA)对69块不同产地琥珀、柯巴、热处理琥珀和压制琥珀中C、H、O的质量分数进行了高精度测试,详细讨论了不同产地琥珀及柯巴的化学元素组成变化规律,探讨了琥珀的石化作用、氧化作用、优化处理对其化学元素组成的影响。文章结论有:(1)不同产地琥珀、柯巴、热处理琥珀和压制琥珀的C、H、O元素组成特征上略有差异,其中H元素质量分数变化不大,琥珀石化作用对琥珀中H的质量分数影响不明显;(2)缅甸琥珀中C的平均质量分数最高,O的最低;柯巴中C的平均质量分数最低,O的最高,且C、O平均质量分数随琥珀石化程度的增加呈反相关关系;(3)在琥珀及柯巴的C-O质量分数关系图中,除了多米尼加琥珀外,缅甸琥珀、波罗的海琥珀和柯巴具有很好的分区性,这表明根据元素质量分数可以为琥珀的产地信息提供依据;(4)不同产地琥珀样品风化皮中O的质量分数明显高于同一样品内部,揭示了长时间的风化过程中环境氧与琥珀表层分子发生了氧化反应,致使琥珀形成一层厚薄不等的褐红色风化外皮;(5)短时间较高温度的优化处理(热处理、压制处理),对琥珀及柯巴整体的C、H、O的质量分数无明显影响。     

300网线与150网线印刷品的比较

1前言印刷品复制质量的好坏主要是从图像的颜色复制和阶调层次复制两方面来进行评价。阶调层次复制主要取决于单位面积内的网点个数和网点由小到大连续变化的级数,单位面积内的网点个数越多,复制印刷品的清晰度越高,层次越丰富,色彩越逼真;网点变化级数越多,印刷品层次表现力越强,看起来越细腻。在印刷生产过程中人们通过改变加网线数来控制单位面积内的网点个数,加网线数越高,单位面积内的网点个数就越多,所再现的网点大小就越小。目前常用的铜版纸加网线数在150～175lpi之间。但是随着人们欣赏水平的不断提高,这种精度的印刷品已经不能满…     

猪骨骼肌组织学特性与猪肉嫩度关系的研究

目的:研究背最长肌和腰大肌的肌纤维直径、肌纤维密度及肌内脂肪百分面积对肌肉嫩度等的影响力或贡献力;方法:对6个杂交组合猪(N=36)的骨骼肌组织形态特征进行二维显微图像重建和与肌肉嫩度的数学关系拟合(n=36×2或×3);结果:腰大肌的肌纤维直径和密度分别比背最长肌细且密,但肌内脂肪百分面积普遍小于背最长肌.肌纤维直径对肌肉嫩度的影响力最大(r=0.966,P<0.01),直径越粗肌肉嫩度越差.肌纤维密度随直径而变化,肌纤维直径越粗,单位面积肌纤维密度越低,且与肌肉嫩度呈显著性相关(r=0.905,P<0.05),肌纤维密度越大肌肉嫩度越好,但贡献力小于肌纤维直径.肌内脂肪百分面积仪占与肌肉总面积的3%左右,本实验数据证实其不足以影响猪肉嫩度;结论:骨骼肌嫩度受肌纤维直径和密度影响较大,一定范围内肌内脂肪可能更多地影响猪肉的风味,而不是嫩度.     

食品中的泡沫

食品中的泡沫是气体分散在液体或半固体中的分散体系。在稳定的泡沫中,气泡是由有弹性的液体股或半固体膜分隔开来。气泡的直径大约从lμm到数厘米,作为分散相的气泡常常呈多面体而不是球形。由于气泡的大小以及膜厚度的不同,泡沫可能像连续相(液体)那么重,也不可能像分散相(气体)那么轻。典型     

琥珀人工与机器雕刻的结合

为探索琥珀人工与机器雕刻的结合工艺,论述了琥珀在雕刻过程中,对刀工要求高、细腻细致,把奇思妙想通过雕琢栩栩如生地体现出来.与其他珠宝工艺品相比,琥珀材料可塑性强,但材质富含包裹体,如气泡、气液包裹体、动植物包裹体等,制作过程中有许多不定性.分析结果得出,人工雕刻制作可解决大部分问题,但速度上无法和机器雕刻媲美.因此,大...     

更正说明

正2016年《宝石和宝石学杂志》第18卷第5期刊登的《蜜蜡中气泡特征与品质的关系》一文,应补充文章的基金项目。基金项目:中国地质大学(武汉)珠宝检测技术     

硅片用切割钢丝生产及断线分析

介绍切割钢丝生产的工艺要求和过程,分析切割钢丝断丝原因:(1)原料材质不合格或钢丝存在表面缺陷;(2)排线间距混乱或钢丝端末滑跑导致压线;(3)切割工艺不当。给出预防措施:(1)加强来料检验,严格生产过程控制,避免各个工序对钢丝表面的损伤;(2)控制工字轮排线角度在10°内,严格端末固定作业程序,用户打结作业前不可将防止压线的胶带提前撕掉;(3)在多线切割中,单位钢丝内切割的硅棒面积越小,钢丝的断线率越低,控制切割系数小于120。在使用过程中针对钢丝的断线原因,适当采取预防措施可以很好的控制断线率,从而节约切割成本,提高硅片质量。     

一种简易的尿激酶活性测定方法

本研究改良了溶栓酶筛选采用的平板法,建立了一种新的尿激酶活性测定方法。该方法以琼脂糖为载体,纤维蛋白原经凝血酶激活后转变为纤维蛋白形成凝块,再经尿激酶作用使其溶解,形成透明圈,透明圈的面积与尿激酶的活性大小呈正相关。与《药典》中使用的气泡法测定尿激酶活性相比该方法成本低、操作简单、重复性好。     

多米尼加蓝珀的快速鉴定与识别

琥珀原料的著名产地分别为多米尼加(蓝珀)、波罗的海(蜜蜡)、缅甸(血珀)等,其中蓝珀拥有其特有的评定依据:其中不单单依据色度,还包括对其内含物多少来评定等级。其内含物越少,色度又越趋向天空蓝,此多米蓝珀的价格才相应越高,收藏价值更大。也因为其较高的收藏价值和经济价值,近几年多米尼加蓝珀备受玩家追捧,因而快速鉴定识别真假蓝珀的技能成为玩家的必备知识之一。     

压制琥珀的新认识

随着琥珀市场需求的增加及琥珀优化处理技术的改进与创新,压制琥珀呈现外观逼真、结构复杂、方法多样的新态势。利用宝石显微镜、偏光显微镜、红外光谱仪对压制金珀、压制血珀、"爆花"压制琥珀、烤色压制琥珀、压固蓝珀、压固胶结蓝珀、压制蜜蜡等样品的宝石学参数、显微结构、红外吸收光谱进行了研究与分析,结果显示,碎粒-碎粉结构、红色斑点结构、不含"血丝"状构造的粒状"镶嵌"结构、碎块胶结结构等是压制琥珀的结构鉴定特征;颗粒间分布的"太阳光芒"、紊乱流纹、叶脉状流纹、丝瓜瓤状流纹等是压制琥珀的内含物鉴定特征;若蓝珀中的红外光谱I=2 932cm-1/I=1 723cm-1处的吸收强度比值接近1∶1,暗示着该蓝珀可能经过了优化处理。     

Impact of air bubbles in a dielectric liquid when subjected to high field strengths

The dielectric breakdown of gas bubbles entrapped in liquid food flowing through the cavity of a pulsed electric field treatment chamber has been a limiting factor in this non-thermal food preservation technology. Prediction of electric field enhancement due to gas bubbles is an important tool in the design, modification, and optimization of the treatment chamber's electrode geometry and pressurization. Simulation of the electrostatic characteristics of a coaxial treatment chamber with specified voltage of 25 kV, filled with dielectric material with conductivity of 0.6 S/m containing gas bubbles, evidenced a significant perturbation in the electric field. The magnitude of electric fields generated inside the bubbles was almost two times higher than in the homogeneous food. Without pressurization (atmospheric conditions), the dielectric breakdown strength of the gas-filled bubbles was exceeded, thus indicating the risk of arcing. A system pressurization of approximately 8 atm could be sufficient to limit arcing when small gas bubbles (∼1 mm) are present. The presence of gas bubbles caused the field magnitude to decrease significantly near the boundary of the bubble, thus threatening the uniformity of the PEF treatment across the chamber gap. This perturbation in the electric field was more significant when more than one bubble was present or when smaller gaps were used. The dielectric breakdown threshold at a given pressure is more likely to be exceeded by bigger bubbles (>1 mm) entrapped in a fluid processed in smaller treatment chamber gaps (3 mm), than by smaller bubbles (<0.5 mm) in bigger gaps (5 mm). Simulations like those used in this research can be conducted to evaluate and optimize process homogeneity and safety, by studying the effects of different treatment chamber configurations, gaps, food products, number of gas-filled bubbles, or other suspended elements in the food.     

计算机辅助X光断层扫描对半甜韧性饼干的质构无损量化检测

采用X光计算断层扫描（X-ray computed tomography,CT）法研究了半甜韧性饼干（以下简称饼干）的 质构特征,并将CT参数与饼干常规物理参数进行了相关性研究。结果显示：CT测试所获得的组织重构可以直观再 现饼干的内部结构（二维及三维）;CT密度、孔隙率以及气泡截面积的平均值与饼干面团中蛋白酶或焦亚硫酸钠 （以下简称焦亚）的添加量、饼干厚度以及表观密度具有显著相关性（R＞0.9,P＜0.05）,反映出CT参数可以客 观地量化由于蛋白酶或焦亚添加量不同所导致的饼干组织结构变化。当蛋白酶或焦亚对面团产生程度相当的减弱面 筋（减筋）作用时,两种面团饼干的常规物理参数及CT参数均表现出显著性差异（P＜0.05）,并且饼干气泡截面 积的分布也表现出不同的特征,表明CT参数可以反映由于不同的减筋原理导致的饼干质构差异。结果表明,CT测 试可以应用于饼干质构的定性和定量测定,为饼干的生产与研究提供有益的信息。     

纤维尺度下数码纱仿真方法

为解决因配色复杂多变,数码纱外观难以直观预测的问题,提出基于纤维单元的模拟方法,用于实现数码纱外观的仿真。依据纤维原料颜色数值,构建纤维级别的纹理模型;根据纺纱工艺参数计算数码纱上的区域色块参数,构建色块排列模型;利用不同组分纤维间渐变规律,同时结合光照模型仿真亮度信息构建颜色渐变模型;采集真实数码纱的直径数据,仿真纱线的直径形态。实验中分别保持颜色和组分不变,模拟出不同组分和颜色的数码纱。结果证明所提出的纱线仿真方法可较快地模拟出数码纱的外观,并且与实际数码纱的外观视觉十分接近,为数码纱的设计开发以及织物仿真奠定了基础。     

Extrusion Cooking Process for Amaranth (Amaranthus caudatus L.)

ABSTRACT: Amaranth ( Amaranthus caudatus L.) extrusion was optimized by response surface methodology (RSM). Response (dependent) variables were: expansion ratio, shearing strength, and sensory texture acceptability. Independent variables were processing temperature and feed moisture. All other process variables (screw speed, screw compression ratio, feed speed, and die diameter) were kept constant (200 rpm, 70 g.min⁻¹, and 3 mm, respectively). The most expanded products also had the best texture and were obtained at 150 °C and 15% moisture. These conditions resulted in greater expansion, greater shearing force of extrudates, greater extrudate surface area per unit weight, and reduced shearing stress at maximum shearing force. This study showed that under conditions that induced the maximum expansion ratio, extrusion produced a highly acceptable snack product based on amaranth flour.     

Identifying industrial food foam structures by 2D surface image analysis and pattern recognition

Bubbles are fundamental structural elements in several food products modulating density, rheology, texture, appearance and mouthfeel. Foams and aerated structures are characterized by their gas content, stability, bubble size and distribution. However, these measures alone cannot fully describe the complexity of bubble-containing structures. We have used three image analysis methods (Euler characteristic, Minkowski fractal and image texture) to characterize foam structure, and canonical and Bayesian discriminant analysis to identify/classify different foam architectures. This work describes results of this methodology on liquid foams stabilized by proteins at varying concentration and pH levels. Results indicated that groups of three structural parameters (among the 57 calculated) could successfully identify foam structures with different characteristics but unfortunately no single set of features could be used ubiquitously. Additional foam structure information as determined in this work can help to better understand these systems and the impact of bubbles on the physical properties of aerated foods.     

Evaluation and comparison of different dough leavening agents on quality of lavash bread

Dough preparation process is an important stage of bread production which has a significant effect on quality of the end product. Bakery yeast, sourdough and chemical leavening agents are used as leavening agents for the treatment of dough for bread. In this study, bakery yeast, sourdough, sodium bicarbonate and combination of bakery yeast and sodium bicarbonate were used for the production of flat bread (lavash). The firmness of lavash bread texture was analyzed using a texture analyzer device and bread staling at 24, 48 and 72 h after baking was analyzed using DSC device. Also, microstructure of bread was studied by scanning electron microscopy (SEM). The results of DSC showed that bread produced with combination of bakery yeast and sodium bicarbonate, had lower enthalpy (279.84 ± 70.47 J/g) and staling than the other samples. Also, hardness of this sample was low (7.608 ± 0.892 N). The images obtained from SEM showed that diameter of gas bubbles in the bread produced with bakery yeast and combination of bakery yeast and sodium bicarbonate, were higher and their cell walls were thinner.     

Structure–fracture relationships in gas-filled gelatin gels

Food aeration has become one of the fastest growing unit operations practiced in the food industry. Dispersed air (or other gases) provides an additional phase within the gel that may accommodate new textural and functional demands. This paper addresses the relationships between structural characteristics and fracture properties of gas-filled gelatin gels (GGG), and compare these properties with those of control gelatin gels (CGG). Three gases were used in the fabrication of GGG: air, nitrogen and helium. Experimental methods to determine density, gas hold-up, bubble sizes and bubble size distributions as well as fracture properties of GGG are presented. Increasing protein concentration produced higher density, lower gas hold-up and decreased polydispersity of bubbles due to its effect on increased solution viscosity. Type of gas affected density and gas hold-up due to the different diffusivities of gases and structures (bubble size, size distribution and number of bubbles per area) formed in GGG. Fracture values increased for both GGG and CGG with increasing protein concentration for the three gases used. GGG were weaker and less ductile than CGG, the decrease in stress and strain at fracture being between 70 and 80%, and 40 and 65%, respectively. A power law relationship (σ_f = 2.73 × 10⁻¹²ρ_G^4.76) was found between the fracture stress and gel density for the three gases studied. This study shows that the presence of bubbles in gel-based food products results in unique textural properties conferred by the additional gaseous phase.     

种植密度对直播油菜结实期源库关系及产量的调节

对6种种植密度下直播甘蓝型油菜结实期的源库关系及产量进行了研究。结果表明：角果长、宽分别在开花后19d和25d左右达到最大值,角果大小有随密度增加而减少的趋势;单位角果皮面积承担的籽粒数（SNPA）及单位角果皮面积的籽粒重（PPA）都随密度的增大呈先增后减的趋势;每角粒数和角果长度或角果面积都符合二次曲线关系;随着种植密度的增加（超过1．97万株／667m^2）,株高、茎粗、单株一次有效分枝数、单株角果数、每果粒数和千粒重均下降,但群体单位面积角果数、角果面积增大,产量增高。密度继续增加,群体单位面积角果数和角果面积减少,产量下降。     

盐水浸泡腌制过程中鸭蛋壳裂的成因

研究了用盐水浸泡法腌制过程中,鸭蛋盐分含量、蛋重、蛋壳比重、蛋壳厚度、气孔数、气室直径、单位面积蛋壳脆性、强度和蛋壳截面微观结构的变化。结果表明,5周内,随着盐分含量的增加,鸭蛋重从61.85 g增加至63.16 g;蛋壳比重、蛋壳厚度均无明显变化,气室直径稍有变化;气孔数从24.93个/0.25 cm2减少至10.40个/0.25 cm2;蛋壳脆性和强度分别从445.2N和1461.2N降至240.6N和446.1N;蛋壳强度从44.504 N降至34.452 N。鸭蛋蛋壳比重低于10%、蛋壳厚度低于0.355 mm、蛋形指数在1.380～1.460低强度范围内腌制期间易裂壳。腌制5周后,蛋壳截面纹路多、有不规则断层;裂壳蛋的壳截面显粗糙、有不规则断裂,乳突排列不均,壳膜结构松散。鸭蛋壳裂的产生是由新鲜鸭蛋壳质量决定,盐水腌制破坏了蛋壳的微观结构和脆性、强度,并对壳裂起到了促进作用。