黄玉的辐照改色及赋色机制

通过辐照处理可以改变黄玉的颜色. 系统地阐述了天然黄玉的颜色, 综述了国内外在黄玉辐照改色技术方面的研究成果, 并对黄玉及辐照处理黄玉颜色的赋色机制进行了探讨, 初步认为黄玉的颜色是由杂质元素、杂质离子心、电子-空穴心共同作用引起的.     

养殖珍珠的辐照改色处理实验

颜色是评价珍珠品质的重要因素,珍珠的颜色丰富多彩．颜色差异直接影响其价格高低。近年来．市场上出现了大量的改色珍珠．特别是辐照处理改色珍珠。由于各国对有关珍珠改色的具体技术方法和工艺细节严加保密．限制了珍珠改色机理的研究和我国珍珠改色技术的发展。本文以海水养殖珍珠和淡水养殖珍珠为研究对象,通过辐照处理改色实验．对珍珠辐照处理的改色方法进行了探讨,并与天然黑色珍珠进行了系统分析比较。为它们的鉴别提供了有效的鉴别特征。     

天然珠宝首饰的放射性,辐照改色及豁免值

天然珠宝首饰集装饰性、纪念性、保值性和保健性于一体,是个人身份、地位、修养、风格的浓缩和展示,是生活高质量和高品位的体现。然而,佩戴天然珠宝首饰对人体是有益或者有害,一直众说纷云。有的说得神乎其神,有的又骇人听闻:“宝石中都含有放射性”、“越是名贵的宝石越有害”等等。笔者毕生从事天然放射性矿物的寻找和研究,本文从科学的角度对上述问题作一些探讨,以期消除广大消费者心中的疑虑。一、含天然放射性元素的宝石     

宝石处理综述

颜色或纯净度有缺陷的宝石可以在很大程度上进行处理（Ｎａｓｓａｕ ,１９９４）。据估计现在市面上的珠宝中有三分之二的有色宝石是经过改善处理的 ,而用于钻石的改善处理也越来越多。改善宝石所需要考虑的重要因素有 :①处理后稳定性 ,即在正常穿戴和展示的条件下是否稳定（如 ,暴露在没有额外加热的光线下 ,在重新抛光的情况下等） ;②处理后的结果是否能用标准的宝石检测方法鉴定出来 ;③处理后能否象人们希望那样可以被恢复。表１（上部）总结了各种珠宝材料采用简单加热的处理效果。这些热处理后的材料都是稳定的 ,而且大部分是可以恢…     

黄玉宝石及其改善处理

提出了黄玉宝石的正确名称,论述了各种产状黄玉的形态、颜色及改色处理方法,对黄玉颜色的形成机理也有阐述。     

中国珠宝首饰市场上优化处理的部分有色宝石

在中国珠宝首饰市场上,许多有色宝石是经过优化处理的。例如：红宝石与蓝宝石绝大部分是经过热处理的,有些红宝石是经过玻璃充填处理的,有些蓝宝石是经过表面扩散处理的;蓝色托帕石几乎都是经过放射线辐照处理的;粉红色或桃红色的碧玺大多数是经过放射线辐照处理的：蓝色海蓝宝石大部分也是经过热处理的,金黄色海蓝宝石是经过放射线辐照处理的;不少琥珀是由小块经过加热压成大块的,加压的快慢可以产生“太阳花”效果;部分黑色珍珠是经过放射线辐照处理的,部分金黄色和蓝色珍珠是经过染色的;很多绿松石是经过充填或经过染色后再充填处理的;翡翠B货是经过净化后再进行充胶处理的;还有将无色水晶或无色托帕石进行表面真空镀膜处理等等。     

不同照明光源对彩色宝石颜色呈现的影响

彩色宝石的颜色是决定其价值最主要的因素,而光源又是影响彩色宝石颜色呈现最主要的因素.宝石在不同光源下颜色的细微差别会对商业价值产生影响,充分的颜色呈现可以更好地吸引消费者的目光,增强顾客的消费欲望,促进珠宝销售.本文选取了5种不同颜色(红、黄、绿、蓝、紫)的宝石作为研究对象,用相机采集各宝石在4种常见光源下的照片.基于...     

服装标识对人体舒适性的影响因素分析

通过对服装标识及其引起人体不适性的现状进行概述和分析,进而对服装标识影响人体舒适性的相关因素分物理和化学两个方面进行分析和探讨,并推出服装标识影响人体舒适性因素的相关函数关系组,期望对服装标识不适性问题的解决提供理论参考.     

如何改善锦纶空变丝织物的耐皂洗牢度

以较具代表性的一个锦纶空变丝织物品种──N088达土伦为例,探讨提高该类织物皂洗牢度的方法。     

THE ENHANCEMENT OF AMMONIA PRETREATMENT ON THE FERMENTATION OF RICE STRAW HYDROLYSATE TO XYLITOL

In xylitol fermentation from rice straw hydrolysate by Candida tropicalis As2.1776, ammonia steeping was employed to pretreat the rice straw. Experimental results showed that the content of toxic compounds created in the hydrolysis process, such as acetic acid and phenolic compounds, was greatly reduced and the fermentation of the hydrolysate was enhanced. Xylitol fermentation was investigated in flasks and a 2‐L bioreactor, respectively. The xylitol yield factor and volumetric productivity were 0.746 g/g and 0.686 g/(L·h) in the lab‐flask fermentation, respectively. The corresponding results conducted in bioreactor fermentation were 0.689 g/g and 0.697 g/(L·h), respectively.     

IRRADIATION AS AN ALTERNATIVE TO METHYL BROMIDE FOR QUARANTINE TREATMENT OF STONE FRUITS1

Irradiation can be used with cherries, apricots, or peaches as a quarantine treatment at 300gy's or less with little quality loss. Either irradiation or methyl bromide (MeBr) can be used as a quarantine treatment for ‘Bing’‘and ‘Rainier’ sweet cherries with acceptable results and similar fruit quality. Difference in stem condition and bruising were more evident for irradiated ‘Rainier’ cherries than for MeBr treated ‘Rainier’ cherries, but these differences were small. Use of irradiation results in some firmness loss, for ‘Bing’ cherries when compared with MeBr, but irradiation treatment of cherries does not result in a loss of fruit and stem color, where the use of MeBr doses result in both fruit and stem color loss. Apricots (‘Perfection’ and ‘Rival’) and peaches (‘Regina’) are tolerant to irradiation at 300 gy with little quality loss. Loss of firmness, color changes and increased internal breakdown are evident in both apricots and peaches at irradiation dose above 600 gy. If irradiation dose above 600 gy is required to meet quarantine requirements unacceptable qualidy loss will occur in cherries, apricots and peaches.     

TEXTURE AND COLOUR CHANGES IN MEAT DURING COOKING RELATED TO THERMAL DENATURATION OF MUSCLE PROTEINS1

Differential scanning calorimetry was used to select temperatures that diferentiated between thermal denaturation of the three major structural protein species in bovine muscle: myosin, collagen and actin. Samples of m. semimembranosus, m. semitendinosus and m. psoas major were heated to those different temperatures and evaluated sensorially. Three groups of sensory properties were needed to describe the main texture changes observed in the meat: 1. Firmness 2. Fiber cohesivity, bite-off force, residual bolus 3. Juiciness Firmness increased with thermal denaturation of the myofibrillar proteins (myosin; 40-60d?C and actin; 66-73d?C). Fiber cohesivity etc. decreased with collagen denaturation (56-62d?C). Reduction in juiciness was primarily associated with actin denaturation, while cooking loss increased over the whole temperature range. The property “total chewing work”, a composite of the first two texture groups mentioned, yielded like the judges' “total texture preference”, optimal texture in the 60-67d?C temperature region, implying denatured myosin and collagen but native actin. This meat was light pink-gray in colour, while the cooking juice released was dark red.     

CAFFEINE IS NON-MUTAGENIC TO SALMONELLA TYPHIMURIUM AND HUMAN CELLS IN CULTURE

Caffeine (1,3,7-trimethylxanthine) was inactive as a mutagen at the hgprt locus in two human lymphoblast lines at concentrations up to 20 mM. In addition, caffeine did not induce 8-azaguanine-resistant mutants in Salmonella typhimurium at similar levels.     

EFFECT ON SEMLIKI FOREST VIRUS AND COXSACKIEVIRUS B4 OF LIPIDS COMMON TO HUMAN MILK

A lipid-enveloped virus (Semliki Forest virus: SFV) and a nonenveloped virus (coxsackievirus B4) were treated with neutral lipids known to be present in human milk or able to be generated by lipase activity in human milk. Triglycerides and diglycerides were inactive compared to monoglycerides and free fatty acids which were active against SFV (90% inactivation) at concentrations as low as 0.7 μM. Of the compounds tested monolinolein was the most active against SFV. None of the lipids tested were active against coxsackievirus B4. A synthetic milk (Almiron-M2), high in unsaturated triglycerides, was inactive against either virus.