珍珠粉和贝壳粉的化学成分和结构特征分析

<正>珍珠粉是将珍珠贝壳动物马氏珠母贝、蚌科动物三角帆蚌或褶纹冠蚌等双壳动物受刺激形成的珍珠用物理的方法粉碎磨细而成的粉状物,自古以来就是名贵中药,具有安神定惊、明目消翳、解毒生肌之功效[1]。但是,市场上常出现以将蚌壳用碱去除其表面的角质层研细而成的贝壳粉,混充珍珠粉。查阅文献发现,由于珍珠粉和贝壳     

三角帆蚌贝壳粉与其珍珠粉的微结构及其光谱学特征

采用扫描电镜(SEM)、热重分析(TG)、傅里叶变换红外光谱(FTIR)及白度测试对三角帆蚌贝壳与其养殖的珍珠研磨粉进行了对比研究。结果表明:1珍珠粉的υ2谱带较于贝壳粉的该谱带存在约1~3cm-1的蓝移,两者文石中的υ1与υ4谱带具有较好的一致性;2 SEM观察下,粉体的颗粒粒径大小与形貌特征并不能作为贝壳粉与珍珠粉区分鉴别的依据。3随煅烧温度的升高,贝壳粉与珍珠粉的白度先下降后升高,珍珠粉白度降低的速率高于贝壳粉,且煅烧后珍珠粉的白度最低值低于煅烧贝壳粉的白度最低值。     

铈对三角帆蚌钙代谢影响的研究

研究了不同浓度稀土Ce3+(0,0.5,1.0,2.5 mg·L-1)处理30,60 d时对2龄植片三角帆蚌钙代谢和珍珠质沉积的影响。结果表明:Ce3+对三角帆蚌珍珠质沉积量、外套膜和鳃组织中组织钙含量、钙调蛋白基因mRNA的表达量、腺苷三磷酸酶(ATPase)活性、碱性磷酸酶(ALP)活性的影响总体上均表现出明显的"低促高抑"的剂量效应和高浓度下"先促后抑"的时间效应。推测稀土Ce3+对钙调蛋白基因mRNA表达水平及关键酶活性的调节可能是其影响三角帆蚌钙代谢和珍珠质沉积的途径之一。     

贝壳珍珠层及其仿生材料的研究进展

贝壳珍珠层是一种天然的有机-无机层状复合材料, 其独特的多尺度、多级次“砖-泥”组装结构赋予其优异的机械性能. 受贝壳珍珠层启发, 人们已利用不同方法制备了一系列仿生高强超韧层状复合材料, 这些材料在航空航天、军事、民用工程及机械等领域表现出广阔的应用前景. 本文就贝壳珍珠层的结构及增韧机制和近年来仿贝壳材料的制备方法及其研究进展进行了综述, 并提出一些看法和思考.     

电子背散射衍射法研究马氏珠母贝珍珠层中文石择优取向

贝壳珍珠层中的文石相对于在自然环境中生长的文石来说具有更优异的力学性能,这种力学性能取决于其独特的晶体排布方式。通过电子背散射衍射(EBSD)技术获得了马氏珠母贝中不同文石的结晶学取向信息,结果表明珍珠层中文石晶体的c轴均垂直于珍珠层层面,而a、b轴在平行珍珠层方向上具有两级取向畴结构:在初级畴结构内,相邻畴绕c轴偏转,导致不同畴之间a轴或b轴的取向差约64°。在次级畴结构内,文石板片围绕c轴偏转,导致不同畴之间a轴或b轴取向差在10°或20°左右。这种畴结构为我们认识珍珠层中文石的生长机理提供了有益线索。     

气-液界面有序介孔SiO2无机膜的仿生合成

早在几百万年以前,自然界就通过生物矿化过程形成了结构高度有序的有机/无机复合材料,如哺乳动物的牙床、骨骼以及贝壳珍珠层等[1]。随着对天然生物材料生物矿化过程研究的逐渐深入,材料研究者从中得到极为重要的启示:先形成有机物自组装体,无机先驱物在自组装聚集体与溶液相的界面处发生化学反应,在有机自组装体的模板作用下,形成有机/无机复合体,再将有机模板去除即可得到具有一定形状与组织结构的无机材料。这种模仿生物矿化中无机物在有机物调制下形成过程的材料合成,称为仿生合成(biomimetic synthesis)[2]。仿生合成过程中,通过选择有…     

淡海水养殖珍珠的紫外-可见吸收光谱特性研究

用紫外-可见吸收光谱法对淡、海水养殖的珍珠表面的珍珠层进行了吸收谱图的对比研究。结果表明:海水养殖的黑色和金色珍珠与淡水养殖的白色、紫色和粉色珍珠,均在其吸收光谱图中波长280nm处出现特征吸收峰,且在淡水及海水贝壳的内表面珍珠层的吸收光谱图的相同波长处也都能见到此吸收峰。鉴于上述珍珠表面及贝壳的内表面均存在生物成因文石板片和有机质周期性排列的珍珠层结构,初步推测上述特征吸收峰与此结构有关,且认为该吸收峰可作为珍珠染色处理较重要的定性指标之一。     

电子背散射衍射法研究马氏珠母贝珍珠层中文石择优取向

贝壳珍珠层中的文石相对于在自然环境中生长的文石来说具有更优异的力学性能,这种力学性能取决于其独特的晶体排布方式。通过电子背散射衍射（EBSD）技术获得了马氏珠母贝中不同文石的结晶学取向信息,结果表明珍珠层中文石晶体的c轴均垂直于珍珠层层面,而a、b轴在平行珍珠层方向上具有两级取向畴结构：在初级畴结构内,相邻畴绕c轴偏转,导致不同畴之间a轴或b轴的取向差约64°。在次级畴结构内,文石板片围绕c轴偏转,导致不同畴之间a轴或b轴取向差在10°或20°左右。这种畴结构为我们认识珍珠层中文石的生长机理提供了有益线索。     

气相色谱-质谱法测定三角帆蚌珍珠层粉中微量有机化学成分

用气相色谱-质谱法测定三角帆蚌珍珠层粉,用二氯甲烷作溶剂先后在pH2,pH7及pH12的条件下萃取样品溶液,合并所得有机相,在50℃蒸发至1mL供气相色谱-质谱法分析。经DB-5MS毛细管柱分离后,从总离子流色谱图上可辨认17个色谱峰,对其中的11种有机化合物作出了鉴别并对其峰面积用归一化法计算其相对含量。此11种化合物占了总量的70.73%,其中主要化合物为瓢儿菜酰胺、1-氯二十七烷、4,6-二叔丁基-间-甲苯酚、邻苯二甲酸丁基异丁基酯、2-[1-(4-氯苄基)-1,4-二氢吡啶-4-叶立德烯]2,3-二氢茚-1,3-二酮等。     

三角帆蚌黄白黑珍珠元素分析及药用价值评价

珍珠具有定惊安神、明目去翳、解毒生肌、清热堕痰等功效。此外,淡水珍珠还作为一种天然材料应用于化妆品工业[1]。对不同颜色的淡水珍珠的常量及微量元素含量分析,对于探讨珍珠的药用价值及不同色彩形成的机理具有重要意义。1　材料与方法三种不同颜色的珍珠采集于湖北省松滋市小南海,淡水人工养殖的三角帆蚌体内,经蒸馏水清洗后,40°C～45°C鼓风烘干。spectrAAZ(220)原子吸收光谱仪;spectrAAFS(220)原子吸收光谱仪;ICAP9000-2000型等离子体直读光谱仪;马弗炉等。准确称取黄、白、黑三种不同颜色珍珠5g,捣碎后置于马弗炉内550°…     

Mollusk shell nacre ultrastructure correlates with environmental temperature and pressure

Nacre, or mother-of-pearl, the tough, iridescent biomineral lining the inner side of some mollusk shells, has alternating biogenic aragonite (calcium carbonate, CaCO(3)) tablet layers and organic sheets. Nacre has been common in the shells of mollusks since the Ordovician (450 million years ago) and is abundant and well-preserved in the fossil record, e.g., in ammonites. Therefore, if any measurable physical aspect of the nacre structure was correlated with environmental temperatures, one could obtain a structural paleothermometer of ancient climates. Using X-ray absorption near-edge structure (XANES) spectroscopy, Photoelectron emission spectromicroscopy (PEEM), and X-ray linear dichroism we acquired polarization-dependent imaging contrast (PIC) maps of pristine nacre in cross-section. The new PIC-map data reveal that the nacre ultrastructure (nacre tablet width, thickness, and angle spread) is species-specific in at least eight mollusk species from completely different environments: Nautilus pompilius, Haliotis iris, Haliotis rufescens, Bathymodiolus azoricus, Atrina rigida, Lasmigona complanata, Pinctada margaritifera, and Mytilus californianus. Nacre species-specificity is interpreted as a result of adaptation to diverging environments. We found strong correlation between nacre crystal misorientations and environmental temperature, further supported by secondary ion mass spectrometry measurements of in situ δ(18)O in the nacre of one shell. This has far-reaching implications: nacre texture may be used as a paleothermometer of ancient climate, spanning 450 million years of Earth's history.     

马氏珠母贝各部位及其插核珍珠层微量元素的含量及分布

用电感耦合等离子体发射光谱仪检测了马氏珠母贝5个部位及其人工插核珍珠层中的11种微量元素的含量。结果表明,人工插核珍珠层中Se、Si、Zn含量,角质层中B、Co、Fe、Mn含量,内脏囊中P含量,闭壳肌中Cu、Cd含量,人工插核珍珠层、角质层、闭壳肌中V含量较其他部位高;各部位w(Cu)/w(Zn)均小于0.50,其中人工插核珍珠层的w(Cu)/w(Zn)特别小,为0.05。为进一步加工利用和揭示其药用价值提供基础信息。     

Xanthurenic Acid in the Shell Purple Patterns of Crassostrea gigas: First Evidence of an Ommochrome Metabolite in a Mollusk Shell

Ommochromes are one of the least studied groups of natural pigments, frequently confused with melanin and, so far, exclusively found in invertebrates such as cephalopods and butterflies. In this study focused on the purple color of the shells of a mollusk, Crassostrea gigas, the first evidence of a metabolite of ommochromes, xanthurenic acid (XA), was obtained by liquid chromatography combined with mass spectrometry (UPLC-MS). In addition to XA and various porphyrins previously identified, a second group of high molecular weight acid-soluble pigments (HMASP) has been identified with physicochemical and structural characteristics similar to those of ommochromes. In addition, fragmentation of HMASP by tandem mass spectrometry (MS/MS) has revealed a substructure common to XA and ommochromes of the ommatin type. Furthermore, the presence of melanins was excluded by the absence of characteristic by-products among the oxidation residues of HMASP. Altogether, these results show that the purple color of the shells of Crassostrea gigas is a complex association of porphyrins and ommochromes of potentially ommatin or ommin type.     

A chemical, morphological, and electrochemical (XPS, SEM/EDX, CV, and EIS) analysis of electrochemically modified electrode surfaces of natural chalcopyrite (CuFeS2) and pyrite (FeS2) in alkaline solutions

Electrodic surfaces of natural chalcopyrite and natural pyrite minerals (El Teniente mine, Chile) have been studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy including microanalysis (SEM/EDX). For comparison, fractured and polished mineral surfaces were also studied by XPS. In both electrodes, the formation of Fe(III) species containing oxygen were detected and Cu(II) species containing oxygen were additionally detected for chalcopyrite at advanced oxidation states. The presence of Cu(II) species containing oxygen was not detected by XPS for the initial oxidation states of the chalcopyrite. For pyrite, the present results do not allow confirmation of the presence of polysulfurs such as have been previously proposed. In both minerals, the measurements of SEM and EDX show relevant alterations in the respective surfaces when different potential values were applied. The chalcopyrite surface shows the formation of protrusions with a high concentration of oxygen. The pyrite surface shows a layer of modified material with high oxygen content. The modifications detected by XPS, SEM, and EDX allowed the explanation of the complexity of the equivalent circuit used to simulate the experimental EIS data. At high oxidation states, both minerals showed a pseudoinductive loop in the equivalent circuit, which was due to the active electrodissolution of the minerals which takes place through a surface film previously formed.     

Investigation of inclusions trapped inside Libyan desert glass by Raman microscopy

Several specimens of Libyan desert glass (LDG), an enigmatic natural glass from Egypt, were subjected to investigation by micro-Raman spectroscopy. The spectra of inclusions inside the LDG samples were successfully measured through the layers of glass and the mineral species were identified on this basis. The presence of cristobalite as typical for high-temperature melt products was confirmed, together with co-existing quartz. TiO₂ was determined in two polymorphic species rutile and anatase. Micro-Raman spectroscopy proved also the presence of minerals unusual for high-temperature glasses such as anhydrite and aragonite.     

固相萃取-气相色谱-负化学离子源质谱法测定运动场所合成材料面层和稀释剂中的短链氯化石蜡

建立了用于运动场所合成材料面层和稀释剂中短链氯化石蜡（SCCPs）总含量测定的固相萃取-气相色谱-负化学离子源质谱法（SPE-GC-NCI-MS）。对气相色谱和质谱的分析条件进行了优化;试样经超声提取、弗罗里硅土固相萃取小柱净化后,选择性离子监测模式（SIM）扫描,外标法定量。方法在0.0501~100.17 mg/L的宽广范围内有良好的线性关系,线性相关系数R²为0.9995,方法检出限低至0.50 μg/g（即0.000050%）,平均回收率为83.2%~96.3%,相对标准偏差为1.56%~6.02%。对10批次实际样品进行检测,含量在0.016%~0.55%范围内,检测结果满足欧盟对此类物质的限量要求。方法可用于运动场所合成材料面层和稀释剂中短链氯化石蜡的实际检测。     

Autoradiographic study on the distribution of 241Am in the shell of the freshwater zebra mussel Dreissena polymorpha

Autoradiography was used to identify α-track distributions in a series of shell sections from live mussels Dreissena polymorpha Pallas and dissected shells of dead mussels obtained from laboratory experiments using relatively high concentrations of ²⁴¹Am in the exposure media, a required condition for successful use of this autoradiographic technique. A comparable distribution of α-tracks was recorded on autoradiographs from both live and dead shells suggesting that metabolism does not lead to any sizable changes in the process of ²⁴¹Am adsorption (present in the extrapallial fluid) onto the inner surface of shell. Autoradiographs showed a preferential accumulation of ²⁴¹Am in the organic periostracum, whereas the outer and inner shell layers were characterized by a relatively low α-tracks density. No α-tracks were observed in the central part of the shell in any of the samples. These observations will be useful for the development of a general model to explain bioaccumulation and biosorption processes of radionuclides into mollusk shells.     

混合无机酸消解-固相萃取-高效液相色谱-串联质谱法分析贝类壳体中的3种全氟磺酸化合物

建立了采用混合无机酸消解-固相萃取(SPE)-高效液相色谱-电喷雾电离串联质谱(HPLC-ESI-MS/MS)分析贝类壳体中的3种全氟磺酸化合物的方法。将贝壳粉经硝酸/盐酸混合酸消解,用氢氧化钠调节消解液的pH值至6后采用Oasis WAX固相萃取柱富集净化,然后采用内标法通过HPLC-ESI-MS/MS在分时段选择反应监测模式下分析上述全氟磺酸化合物。结果表明,该方法对于贝壳中全氟丁烷磺酸、全氟己烷磺酸和全氟辛烷磺酸的检出限(LOD)分别为0.28, 0.42和0.43 ng/g,加标回收率为94.88%～96.24%。采用此方法对渤海湾两种双壳贝类壳体进行的采样分析也表明,贝壳中3种目标污染物的含量范围为＜LOD～0.70 ng/g,比其在贝类软组织中的含量低约1个数量级。实验结果表明混合酸消解-SPE提取是检测贝类壳体中此类污染物的有效前处理方法。     

质谱在高通量快速检测技术中的应用研究进展

质谱是现代分析测试技术中同时具备了灵敏度高、特异性好、分析速度快等特性的普适性方法,现已被广泛应用于食品检验、环境监测、药物筛选、临床医学等众多领域的高通量快速检测技术中。该文针对近年来低分辨质谱、高分辨质谱以及原位电离质谱技术在高通量快速检测,特别是小分子化合物的高通量快速检测中的应用研究进展进行了综述,并对质谱技术用于高通量快速检测的发展趋势及应用前景进行了展望,以期为相关领域的科技人员提供理论支持和技术参考。     

EPR and IR spectral studies of the sea water mussel Mytilus conradinus shells

The electron paramagnetic resonance (EPR) and infrared (IR) spectral studies have been employed on the periostracum, the prismatic layer and the nacre of the shell of the marine bivalve molluscan Mytilus conradinus of the South Indian origin. All the layers of this shell show Fe3+ ion spin resonance signals in common. The inner layer namely nacre at room temperature shows EPR signals of Fe3+ ions and the heated one exhibits a sextet hyperfine pattern characteristic of Mn2+ ions. The prismatic layer of the shell also exhibits a similar spectrum, but of distinct pattern. The spin-Hamiltonian parameters have been evaluated for the prismatic and nacreous layers of this shell. Infrared spectra of the two main layers of the shell namely prismatic and the nacre exhibit the characteristic bands of CO3(2-) molecular ion in different symmetries of CaCO3.