Strontium Uptake in Shell Aragonite from the Freshwater Gastropod Limnaea stagnalis

Shell aragonite from 96 specimens of the freshwater gastropod Limnaea stagnalis grown in laboratory tanks at different temperatures in water with variable strontium/calcium ratios have been analyzed for its strontium content in order to evaluate the mechanisms of strontium uptake in molluskan aragonite. Within the limits defined by natural freshwater environments, the strontium/calcium ratio in the aragonite was found to be linearly related to the strontium/calcium ratio in the water. A distribution coefficient k(A)(Sr) = 0.237 +/- 0.029, unaffected by variations in temperature and growth rate, has been found. This finding substantiates the existence of a strontium-discriminating effect in aragonite precipitated by mollusks as compared to the case for nonbiogenic aragonite which contains about five times as much strontium when precipitated under the same conditions.     

海藻酸钠热稳定性能的研究

利用DSC和Brabender糊化仪,结合红外图谱对海藻酸钠的热分解过程进行分析,比较了交联海藻酸纳和原料海藻酸钠在加热和冷却时的各种热力学性质的差别以及温度变化对交联海藻酸钠（或海藻酸钠）糊粘度的影响。研究表明,海藻酸钠的降解分为3个阶段;随交联剂加入量的增加,所得交联产物的凝胶性减弱,不易于老化。     

聚乙烯醇和海藻酸钠联合固定化汉逊德巴利酵母产3-羟基丙酸的研究

采用微胶囊固定化技术,利用聚乙烯醇、海藻酸钠和氯化钙制备汉逊德巴利酵母微胶囊,探讨了聚乙烯醇、海藻酸钠、氯化钙的浓度对汉逊德巴利酵母微胶囊的制备工艺及其产3-羟基丙酸量的影响。结果表明,随着聚乙烯醇、海藻酸钠和氯化钙浓度的分别增加,3-羟基丙酸含量先增加后减少。聚乙烯醇最佳浓度为10.0%,此时3-羟基丙酸含量为(20.01±0.66)g/L;海藻酸钠为最佳浓度为1.0%,此时3-羟基丙酸含量为(18.71±0.54)g/L;氯化钙最佳浓度为2.1%,此时3-羟基丙酸含量为(18.37±0.45)g/L。聚乙烯醇和海藻酸钠联合固定汉逊德巴利酵母制备微胶囊最佳工艺为10.0%聚乙烯醇,1.0%海藻酸钠和2.1%氯化钙,在此条件下3-羟基丙酸含量为(21.53±1.12)g/L。     

Evolution of the ratio of strontium-87 to strontium-86 in seawater from cretaceous to present

A detailed record of the strontium-87 to strontium-86 ratio in seawater during the last 100 million years was determined by measuring this ratio in 137 well-preserved and well-dated fossil foraminifera samples. Sample preservation was evaluated from scanning electron microscopy studies, measured strontium-calcium ratios, and pore water strontium isotope ratios. The evolution of the strontium isotopic ratio in seawater offers a means to evaluate long-term changes in the global strontium isotope mass balance. Results show that the marine strontium isotope composition can be used for correlating and dating well-preserved authigenic marine sediments throughout much of the Cenozoic to a precision of +/-1 million years. The strontium-87 to strontium-86 ratio in seawater increased sharply across the Cretaceous/Tertiary boundary, but this feature is not readily explained as strontium input from a bolide impact on land.     

茶多酚/海藻酸钠膜对黄瓜保鲜效果的影响研究

采用茶多酚和海藻酸钠混合液对黄瓜进行涂膜处理,通过测定贮藏期内黄瓜的硬度、失重率、Vc含量、可溶性固形物含量及叶绿素含量,探讨茶多酚/海藻酸钠涂膜对黄瓜的保鲜效果。结果表明:茶多酚/海藻酸钠涂膜比单一海藻酸钠涂膜对黄瓜的保鲜效果好,1.5%的海藻酸钠溶液中加入0.3%的茶多酚对黄瓜的保鲜效果最佳,贮藏期内能够抑制黄瓜水分的散失,减缓硬度、可溶性固形物、Vc和叶绿素含量的下降。     

垂柳幼苗对锶胁迫的生理生化响应

[目的]探讨垂柳幼苗对锶胁迫的生理生化响应。[方法]在水培条件下研究了不同浓度的锶(Sr2+)胁迫对垂柳幼苗生理生化水平的影响。[结果]在锶胁迫下,低浓度Sr2+对垂柳幼苗的地上生物量、叶绿素含量以及超氧化物酶(SOD)活性,表现为促进作用,而高浓度时表现为抑制作用;与对照相比,叶片中丙二醛(MDA)含量显著升高,而脯氨酸含量并没有明显的变化。[结论]该研究为柳树在锶污染胁迫条件下的适应机理奠定了基础。     

Acantharian fluxes and strontium to chlorinity ratios in the north pacific ocean

Data on particulate strontium sulfate fluxes and strontium to chlorinity ratios were compared to provide insights into the strontium cycle of the North Pacific. Freedrifting sediment traps were used to derive large particle fluxes between depths of 100 and 3500 meters in the eastern and western North Pacific Ocean. Flux data revealed substantial quantities of acantharian skeletons and cysts (both made of strontium sulfate) settling through the upper kilometer of the water column. The greatest fluxes of celestite were detected at 400 meters. Minimal to nondetectable fluxes noted at and below 900 meters provide evidence that by this horizon, the majority of acantharian specimens had dissolved, thereby contributing to the pool of dissolved strontium. Growth and subsequent dissolution of acantharians in the upper kilometer are qualitatively consistent with the well-developed minimum and maximum strontium to chlorinity ratios that are consistently noted in these waters. These fluxes of particulate strontium and model calculations for fluxes of dissolved strontium indicate that acantharians play an important role in the ocean's strontium budget.     

二氧化硅和锶的地球化学迁移影响因素研究

[目的]研究在表生地球化学环境下,有益组份二氧化硅和锶在地下水中形成及迁移的影响因素。[方法]通过研究盘山地区含水介质的矿物成分、表生地球化学作用、造岩矿物的风化程度和水交替强度,研究了二氧化硅和锶的地球化学迁移的影响因素。[结果]微量元素锶在风化石英二长岩中的平均含量为0.075%,在原岩中为0.076%。该区流量大于20m3/h的井均位于岩脉两侧或接触带上,年均降雨量677.1mm。半风化岩石的有益组份溶出量最高,新鲜岩石次之,全风化岩石溶出量最少。二氧化硅和锶的溶出受水动力条件影响较大。[结论]盘山地区二氧化硅和锶的地球化学迁移与含水层介质的岩性、表生地球化学作用的发生、造岩矿物的风化程度及地下水交替强度关系密切。     

生姜、大蒜提取液和海藻酸钠复合处理对茵红李的保鲜效果

为了探讨茵红李贮藏保鲜新方法,以海藻酸钠为成膜材料,添加生姜、大蒜提取液配制不同复合保鲜液,研究常温条件下2%海藻酸钠、2%海藻酸钠-大蒜提取液、2%海藻酸钠-生姜提取液和2%海藻酸钠-姜蒜复配液4种不同复合保鲜处理对茵红李采后果实生理指标和品质的影响。结果表明:4种不同保鲜处理均能有效降低果实的失重率,较好地保持果实的好果率、维生素C含量、可溶性固形物含量和可滴定酸含量,有效降低果实呼吸峰值,并使果实呼吸高峰推迟2 d出现。4种不同保鲜处理对茵红李贮藏保鲜效果存在不同程度差异,其中,2%海藻酸钠-姜蒜复配液处理更能有效降低茵红李果实的失重率,较好地保持茵红李的贮藏品质,延长其贮藏寿命。     

壳聚糖/海藻酸钠微球对红景天苷控制释放的研究

将含有药物的海藻酸钠溶液滴入到壳聚糖和氯化钙的混合溶液中形成微球,制备一系列红景天苷微球,研究微球对红景天苷的包载能力及释药特性。结果表明:海藻酸钠、氯化钙、壳聚糖的质量浓度、海藻酸钠与红景天苷的比例及壳聚糖溶液pH值对微球的包埋率、载药率及缓释性能有影响,而成膜反应时间对载药率和包埋率有影响,对缓释性能没有影响。缓释效果最佳的微球制备工艺条件为海藻酸钠与红景天苷质量比为1.5,海藻酸钠2.5 g/mL,壳聚糖0.8 g/mL,氯化钙1.5 g/mL,成膜时间为5 min,pH值为5.5。     

巨大芽孢杆菌固定化包埋材料的初步研究

对巨大芽孢杆菌的包埋材料进行了初步研究。实验结果表明:3种包埋材料对巨大芽孢杆菌的起始包埋能力不同,其中以2%海藻酸钠+2%明胶的效果最好,是4%海藻酸钠包埋剂的2.22倍。3种包埋颗粒在0.2 mol/L柠檬酸钠溶液中的溶解性能不同,溶解能力大小为:4%海藻酸钠>3%海藻酸钠+0.5%明胶+0.5%淀粉>2%海藻酸钠+2%明胶。保存在包埋剂3%海藻酸钠+0.5%明胶+0.5%淀粉中的巨大芽孢杆菌数量稳定,菌的纯度高,其在3种包埋剂中最有利于巨大芽孢杆菌的保存。     

超低粘度海藻酸钠制备工艺研究

实验先进行单因素分析,研究海藻酸钠水溶液在不同温度、p H值、反应时间条件下粘度的变化规律,得出单因素条件下制备超低粘度海藻酸钠的最适条件。进而进行正交试验,通过方差分析得出制备超低粘度海藻酸钠的最佳条件为：最适温度65℃,p H值2.5,反应时间是8h。通过喷雾干燥技术将超低粘度的海藻酸钠胶液制备成固体粉末。     

番茄施用含海藻酸水溶肥料的研究

含海藻酸水溶肥料是海藻经过特殊生化工艺处理生产的新型肥料,富含多种促进作物生长的天然活性成分。研究了番茄叶面喷施含海藻酸水溶肥料对番茄品质及产量的影响。结果表明,含海藻酸水溶肥料能明显促进番茄生长,改善番茄植株生长状况,株高平均提高13.8～15.3cm,单株结果数增加2.0个,单果重提高3.0～4.7g。     

耐辐射丝状真菌F161的分离鉴定及其对锶的吸附特性

[目的]鉴定分离自新疆某辐射污染区的丝状真菌F161,研究其吸附锶特性.[方法]采用形态学观察、分子生物学鉴定及碳源利用实验鉴定菌种;采用压力试验和吸附试验研究特性,对锶的吸附测定采用ICP-MS,对放射性90锶的吸附的测定采用液闪检测仪.[结果]菌株F161鉴定为青霉属真菌;菌株F161能够耐受10 KGy剂量的钴源...     

内源乳化法制备2;4-D/海藻酸钠/羽毛蛋白微球及其缓释性能

以海藻酸钠(Sodium Alginate,SA)和羽毛蛋白(Feather Protein,FP)为载体材料,2,4-二氯苯氧乙酸(2,4-D)为模型药物,采用内源乳化法制备了2,4-D/SA/FP复合微球,并考察了羽毛蛋白与海藻酸钠的质量比、油水(体积)比、纳米碳酸钙用量对载药微球的形貌、载药性能和缓释性能的影响.结果表明,V(油)∶V(水)=3∶1,羽毛蛋白为海藻酸钠质量的30%,纳米碳酸钙用量为0.2 g时,所制得微球球形度较好,粒径分布较均匀,载药量为3.68%,具有良好的缓释性能.     

不同多糖对冷却牛肉涂膜保鲜效果研究

以冷却牛肉为试验对象,以2%的海藻酸钠、壳聚糖或羧甲基纤维素钠三种多糖为膜材对其进行涂膜保鲜.通过对比和分析保鲜过程中茵落总数、TVB-N值、pH和红度等指标的变化,研究这三种多糖型可食用膜对新鲜牛肉的保鲜效果.结果表明,用海藻酸钠膜处理的牛肉贮藏16d时,肉的pH为6.2,TVB-N值和茵落总数显著低于壳聚糖或羧甲基...     

Precipitate formation in the strontium-phosphate system

Study of the precipitation process in the aqueous Sr(OH)(2)-H(3)PO(4) system, in order to elucidate the phase transformations and the nature of the final solid phases, shows that over much of the range of compositions studied the initial precipitate is poorly crystalline; the x-ray pattern resembles that of strontium hydroxyapatite but has a strontium: phosphorus molar ratio close to 1.3. Within 1 hour the initial precipitate changes to a stable crystalline phase (or phases), with corresponding change, either up or down, in the strontium: phosphorus ratio. At high ratios of Sr(OH)(2) to H(2)PO(4) the initial precipitate is Sr(3)(PO(4))(2)-4H(2)O, which then converts to a phase having the x-ray diffraction pattern of strontium hydroxyapatite, but having a strontium: phosphorus ratio that depends somewhat on the initial ratio of Sr(OH)(2) to H(3)PO(4) used in the precipitation.     

High-magnesian calcite: leaching of magnesium in the deep sea

The high-magnesian calcite fraction of a shallow-water carbonate sand was converted to low-magnesian calcite after transport to the deep sea; strontium was also leached from the carbonate. Oxygen isotopic ratios indicate that loss of magnesium and strontium took place during recrystallization of the carbonate in the deep sea; this process did not alter textures of skeletal fragments. Previously, high-magnesian, calcite was thought only to dissolve in the deep sea.     

海藻酸钠裂解酶产生菌的筛选及酶活性研究

[目的]筛选海藻酸钠高效降解菌并研究其产酶活性。[方法]以海藻酸钠为唯一碳源,通过驯化培养、初筛、复筛得到一株优势菌,并对该菌的最适生长条件、最适产酶条件及酶的性质作了初步研究。[结果]优选出1株海藻酸钠高效降解菌8号菌株,为革兰氏阴性菌,形态为杆状。该菌在30℃培养72h产酶量最高。海藻酸钠裂解酶作用的最适底物质量分数为1．00％～2．00％,最适pH值为7．o,最适反应温度为4JD℃,温度继续升高,酶活力急剧下降。[结论]为海藻酸钠的有效降解提供了科学依据。     

Strontium incorporation into dental enamel

Rats were raised on diets either rich or poor in strontium. Powder x-ray diffraction patterns suggest that isomorphous substitution of strontium for calcium occurs in the apatite of tooth enamel, and that strontium may form Sr(6)H(3)(PO(4)) * 2H(2)O, a compound hitherto unreported in biologic systems.