Imaging powders with the atomic force microscope: from biominerals to commercial materials

Atomically resolved images of pressed powder samples have been obtained with the atomic force microscope (AFM). The technique was successful in resolving the particle, domain, and atomic structure of pismo clam (Tivela stultorum) and sea urchin (Strongylocentrotus purpuratus) shells and of commercially available calcium carbonate (CaCO(3)) and strontium carbonate (SrCO(3)) powders. Grinding and subsequent pressing of the shells did not destroy the microstructure of these materials. The atomic-resolution imaging capabilities of AFM can be applied to polycrystalline samples by means of pressing powders with a grain size as small as 50 micrometers. These results illustrate that the AFM is a promising tool for material science and the study of biomineralization.     

Siliceous tablets in the larval shells of apatitic discinid brachiopods

The marine bivalved Brachiopoda are abundant throughout the geological record and have apatitic (CaPO4-rich) or calcitic (CaCO3-rich) shells. Vesicles covering the larval valves of living apatitic-shelled discinids contain tablets of silica. The tablets are cemented into close-packed mosaics by spherular apatite in glycosaminoglycans. They are usually lost as vesicles degrade but leave imprints on the underlying apatitic shell. Similar imprints ornament larval surfaces of some of the earliest Paleozoic apatitic-shelled brachiopods and may also be indicators of siliceous biomineralization.     

补饲CaCO3对猪肉系水力的影响

选用体重相近(85 kg左右)的杜长大三元杂交猪20 头,随机分成5组,其中1组为对照组,饲喂基础日粮,其余4组为试验组,分别在基础日粮的基础上每日补饲CaCO37.5或15.0 g,连续补饲5或10 d即屠宰.通过对滴水损失、煮熟率的测定来评价补饲CaCO3对猪肉系水力的影响.结果显示:补饲CaCO3不影响各部位猪肉的滴水损失和熟肉率(P＞0.05),即不影响猪肉的系水力.     

Calcium carbonate concretions formed by the decomposition of organic matter

Bacterial decomposition of butterfish and smelts in small sealed jars containing seawater and other solutions, for periods ranging from 65 to 205 days, results in a large increase in concentrations of dissolved bicarbonate, carbonate, and ammonia (plus volatile amines). Accompanying this is a rise in pH and the precipitation of Ca(++) ion from solution. The Ca(++) is not precipitated as CaCO(3) but instead as a mixture of calcium fatty acid salts or soaps with from 14 to 18 carbon atoms. This can be explained by the thermodynamic instability of CaCO(3) relative to Ca soaps in the presence of excess free fatty acid. It is suggested that some ancient CaCO(3) concretions, especially those enclosing fossils of soft-bodied organisms, may have formed rapidly after death in the form of natural Ca soap (adipocere) which was later converted to CaCO(3).     

Impact of anthropogenic CO2 on the CaCO3 system in the oceans

Rising atmospheric carbon dioxide (CO2) concentrations over the past two centuries have led to greater CO2 uptake by the oceans. This acidification process has changed the saturation state of the oceans with respect to calcium carbonate (CaCO3) particles. Here we estimate the in situ CaCO3 dissolution rates for the global oceans from total alkalinity and chlorofluorocarbon data, and we also discuss the future impacts of anthropogenic CO2 on CaCO3 shell-forming species. CaCO3 dissolution rates, ranging from 0.003 to 1.2 micromoles per kilogram per year, are observed beginning near the aragonite saturation horizon. The total water column CaCO3 dissolution rate for the global oceans is approximately 0.5 +/- 0.2 petagrams of CaCO3-C per year, which is approximately 45 to 65% of the export production of CaCO3.     

添加剂对土壤外加硒形态变化的影响

报道了在恒温培养下，几种添加剂对外加硒在黄棕壤中不同形态的影响．试验表明，与对照土壤样品比较，经添加ＫＨ２ＰＯ４、Ｋ２ＳＯ４、ＣａＣＯ３、苜蓿和苜蓿＋ＣａＣＯ３，其可溶态Ｋ２ＳＯ４－Ｓｅ和残渣态ｒｅｓｉｄｕｅ－Ｓｅ的百分含量均有不同程度的提高．除添加ＣａＣＯ３外．加入其它添加剂时ＫＮ２ＰＯ－Ｓｅ的百分含量有大幅度的降低，其中以添加ＫＨ２ＰＯ４的最为明显．土壤添加Ｋ２ＳＯ４后氧水提取态ＮＨ３·Ｈ２Ｏ－Ｓｅ变化很小，而其余处理中的下降较多．所有试验中，随着培养时间的增加，交换态ＫＨ２ＰＯ４－Ｓｅ呈缓慢下降趋势，残渣态ｒｅｓｉｄｕｅ—Ｓｅ呈缓慢上升趋势，两者之间相互消长．在整个培养期间．经ＣａＣＯ３处理后的土壤，交换态ＫＨ２ＰＯ４－Ｓｅ和氨水提取态ＮＨ３·Ｈ２Ｏ－Ｓｅ的百分含量相近，而在其余的处理中交换态ＫＨ２ＰＯ４－Ｓｅ小于氨水提取态ＮＨ３·Ｈ２Ｏ－Ｓｅ的百分含量．     

聚二甲基硅氧烷/碳酸钙复合体系流变性能研究

研究了聚二甲基硅氧烷(PDMS)/碳酸钙(CaCO3)复合体系的流变行为.用平板流变仪测得修饰后的碳酸钙复合体系的动态特性发现,随碳酸钙加入量的增加,复合体系的弹性随频率的增大而减小;低频下阻尼系数值明显降低,高频下阻尼系数值基本不变;阻尼系数随频率的增加,变化幅度减小;定频率下的储存模量和损耗模量都随温度的升高而下降.同时在对含量为20%修饰后的碳酸钙复合体系定频下振幅扫描后,没有发现Payne效应的存在.从而表明,修饰后的粒子之间的作用力不大.     

Hydrocalcite (CaCO3 * H2O) and Nesquehonite (MgCO3 * 3H2O) in Carbonate Scales

Hydrocalcite (CaCO(3) * H(2)O) with exactly one molecule of hydrate water is the main component of carbonate scales deposited from cold water in contact with air. When the magnesium content of the water is high, the hydrocalcite occurs together with MgCO(3) * 3H(2)O (nesquehonite). From the conditions under which hydrocalcite is transformed into calcite and aragonite, it appears that in some cases aragonite in nature may be formed by way of an intermediary of CaCO(3) * H(2)O.     

CaCO3对黄豆生长过程中Cd毒害的缓解效应

采用盆栽试验方法,研究了Cd污染土壤中施用CaCO3对黄豆生物量、叶绿素含量、叶片SOD活性和MDA含量的影响,即CaCO3对黄豆生长过程中Cd毒害的缓解效应．结果表明,在Cd污染土壤中,适量施用CaCO3可以显著增加黄豆植株高度、生物量、叶绿素含量和叶片SOD活性,降低叶片MDA含量,说明CaCO3能有效缓解Cd对黄豆的毒害．以黄豆豆荚鲜重为指标,在本试验条件下,未受Cd污染的土壤中,CaCO3的建议施用量为0．5g／kg;Cd污染水平为5mg／kg的土壤中,CaCO3的建议施用量为2g/kg。     

从蟹壳中提取壳多糖工艺的改进

本研究改进了从蟹壳中提取壳多糖的工艺,并以Sigma公司的壳多糖标准品作对照,对产品的主要理化性质进行了鉴别。与以往的工艺相比的结果提示:两种工艺产品纯度相当(98％),收率也相近(16％)。但本文新工艺不需冷却设备,且可节省大量昂贵的碱用量。     

树莓酒不同降酸工艺研究

树莓在我国是一种新兴水果,具有较好的鲜食和加工价值。通过采用CaCO3、KHCO3、K2C4H4O6、复盐法等6种不同降酸方式,分析比较了不同降酸方式的降酸效果及对酒的质量的影响。结果表明：采用KHCO3降酸,能较容易达到树莓酒降酸的要求,但如果用量过大,会使酒体略微表现出苦涩味;利用CaCO3处理,能达到树莓酒降酸目的,而且可以保留原有的香气和口感,但热稳定性差,需要结合离子交换树脂去除Ca2＋;利用K2C4H4O6降酸,用量大,成本高,且易生成KHC4H4O6,清除较麻烦。     

水分和碳酸钙对土壤Cd形态的影响

采用室内连续培养的方法,研究了不同水分条件下,不同用量CaCO3对土壤Cd形态的影响.结果表明:在持续淹水、70%田间持水量及干湿交替条件下,施用不同量CaCO3均明显降低了土壤中可交换态Cd含量,其作用顺序是:CaCO3用量0.4%＞0.2%＞0.1%;而Cd的碳酸盐结合态、铁锰氧化物结合态和有机结合态均增加,其中碳酸盐结合态Cd的增加趋势为CaCO3 0.4%＞0.2%＞0.1%.     

不同添加剂(物)对玉米秸秆青贮有机酸含量的影响

以玉米为原料,添加碳酸钙、尿素、玉米籽实、麸皮、青贮发酵益生菌(Max200)、矿物盐载体结合益生菌合剂以及植物细胞壁降解活性制剂(MixⅡ),通过测定青贮发酵期有机酸含量,评价不同添加剂(物)对青贮效果的影响.结果表明:全贮(全株玉米)中,在发酵期第1、7、14、21d添加MixⅡ组和Max200组乳酸含量均极显著高于其他处理组及对照组(P<0.01),添加MixⅡ组乳酸含量显著高于Max200组(P<0.01);黄贮(摘除果穗)中,在发酵期第1、7、14、21d添加MixⅡ组和Max200组乳酸含量极显著高于其他处理组及对照组(P<0.01),第7、21d添加MixⅡ组乳酸含量显著高于添加Max200组(P<0.01).青贮第21d,添加麸皮组、尿素组、碳酸钙组、Max200组、MixⅡ组和对照组乳酸与乙酸的比值在全贮中分别达到1.93、2.36、1.60、3.74、3.64、2.13,黄贮中分别为1.53、2.25、1.98、2.54、3.11、1.33,添加MixⅡ组和Max200组显著高于其他处理组(P<0.01).发酵期第14d和21d,仅在全贮和黄贮个别样中检测到微量丁酸.     

仔猪对锰利用的研究

试验Ⅰ４０日龄，１２头杂交仔猪（公母各半），采用玉米－豆饼型基础日粮（锰含量为１３．９８７ｍｇ／ｋｇ），分别添加０．０ｍｇ／ｋｇ（对照组）、５．０ｍｇ／ｋｇ（试验组）硫酸锰。试验结果，对照组与试验组仔猪来食量、增重、饲料利用率差异不显著（Ｐ＞０．０５），锰在肝中沉积率试验组显著（Ｐ＜０．０５）高于对照组，在脾中沉积率对照组显著（Ｐ＜０．０５）高于试验组，在讲骨灰中锰沉积率差异不显著（Ｐ＞０．０５）。试验Ⅱ４５日龄，６头来交仔猪（公猪），采用玉米－豆饼基础日粮（锰为１６．２２３ｍｇ／ｋｇ，分别添加０．０ｍｇ／ｋｇ（对照组）、５．０ｍｇ／ｋｇ（试验组）硫酸锰，结果，锰的真实利用率对照组显著高于试验组（Ｐ＜０．０５）     

pH值和碳酸钙对不同形态磷酸盐有效性的影响

本文研究结果,在培养液为ｐＨ６．５,７．５,８．５条件下,Ｃａ２－Ｐ,Ｃａ８－Ｐ和Ｃａ１０－Ｐ处理均随溶液ｐＨ值降低其速效磷含量增加,而Ｆｅ－Ｐ和Ａｌ－Ｐ则随溶液ｐＨ值降低而减少,加入ＣａＣＯ３,各形态磷酸盐有效性明显降低,且ｐＨ值越低下降幅度越大,小麦幼苗对各形态磷酸盐的吸收量均随溶液ｐＨ值降低而增加,当ＣａＣＯ３存在时,小麦幼苗对磷的吸收明显降低,随溶液ｐＨ值的升高,加ＣａＣＯ３与不加处理间差     

Soil Properties and Characteristics of Soil Aggregate in Marginal Farmlands of Oasis in the Middle of Hexi Corridor Region, Northwest China

The composition and stability of soil aggregate are closely related to soil quality, soil erosion, and agricultural sustainability. In this study, 49 soil samples at the 0-10 cm surface layer were collected from four soil types (i.e., Ari-Sandic Primosols, Calci-Orthic Aridosols, Siltigi-Otrthic Anthrosols, and Ustic Cambosols) in the marginal farmland in the oasis of the middle Hexi Corridor region and was used to determine the characteristics of soil aggregates. The composition of dry- and wet- sieved aggregates and the physical and chemical properties (including soil particle distribution, soil organic carbon (SOC), calcium carbonate (CaCO3), and oxides of Fe3+ and Al3t) of the selected soils were analyzed. The results show that soil particle size distribution is dominated by fine sand fraction in most of soils except Ustic Cambosols. Soil organic carbon concentration is 5.88±2.52 g kg-1 on average, ranging from 4.75 g kg-1 in Ari-Sandic Primosols to 10.51 g kg-1 in Ustic Cambosols. The soils have high calcium carbonate (CaCO3) concentration, ranging from 84.7 to 164.8 g kg-1, which is increased with soil fine particle and organic carbon content. The percentage of　＞0.25 mm dry aggregates ranges from 65.2% in Ari-Sandic Primosols to 94.6% in Ustic Cambosols, and large dry blocky aggregates (＞5 mm) is dominant in all soils. The mean weight diameter of dry aggregates (DMWD) ranges from 3.2 mm to 5.5 mm. The percentage of ＞0.25 mm water-stable aggregate is from 23.8% to 45.4%. The percentage of aggregate destruction (PAD) is from 52.4% to 66.8%, which shows a weak aggregate stability. Ari-Sandic Primosols has the highest PAD. The distribution and characteristics of soil aggregates are in favor of controlling soil wind erosion. However, the stability of aggregate of all soils is weak and soils are prone to disperse and harden after irrigation. The mass of macro-aggregates and DMWD are positively significantly correlated with the contents of soil clay and silt, soil organic carbon (SOC), CaCO3, and oxides of Fe3+ and A13+. Soil fine silt and clay, SOC and CaCO3 are important agents of aggregation in this region, and the effect of SOC and CaCO3 on aggregate stability is more significant than that of soil silt and clay. Converting cropland to alfalfa forage land can increase SOC concentration, and in turn, enhance the formation of aggregates and stability. For the marginal farmlands in this fragile ecological area, converting cropland to alfalfa grassland or performing crop-grass rotation is an effective and basic strategy to improve soil structure and quality, to mitigate soil wind erosion, and to enhance oasis agricultural sustainability.     

Geochemical consequences of increased atmospheric carbon dioxide on coral reefs

A coral reef represents the net accumulation of calcium carbonate (CaCO3) produced by corals and other calcifying organisms. If calcification declines, then reef-building capacity also declines. Coral reef calcification depends on the saturation state of the carbonate mineral aragonite of surface waters. By the middle of the next century, an increased concentration of carbon dioxide will decrease the aragonite saturation state in the tropics by 30 percent and biogenic aragonite precipitation by 14 to 30 percent. Coral reefs are particularly threatened, because reef-building organisms secrete metastable forms of CaCO3, but the biogeochemical consequences on other calcifying marine ecosystems may be equally severe.     

碱度调节对南美白对虾室内高密度养殖

【目的】研究碱度调节对南美白对虾养殖水质和生长性状的影响,为零换水有氧异氧养殖系统（ZEAH）适宜碱度的选择提供参考。【方法】采用ZEAH养殖理念,通过泼洒碳酸氢钠（NaHCO3）将12个南美白对虾室内高密度养殖池的碱度分别控制在：T1碱度130 mg/L CaCO3;T2碱度100 mg/L CaCO3;T3碱度70 mg/L CaCO3;T4不调节碱度,每处理设3个重复。在63 d的养殖周期内,定期测量养殖水体理化参数和对虾生长性状参数。【结果】T1和T2处理的养殖水体主要理化参数显著优于T3和T4处理（P＜0.05）,但T1和T2处理间差异不显著（P＞0.05）;各处理的氨氮、亚硝酸盐、硝酸盐、磷酸盐、悬浮物和溶解CO2均随养殖时间的增加不断上升,但高碱度处理上升速率较慢。除成活率和饵料转化率外,T1和T2处理的对虾生长性状参数也显著优于T3和T4处理（P＜0.05）。从维持碱度水平来看,也是以T1（碱度调节间隔时间6~9 d）和T2（碱度调节间隔时间9~12 d）处理的效果较优。【结论】在高密度养殖系统中,使用碱性化合物增加碱度及提高水体缓冲能力是十分有必要的。综合考虑养殖成本和生态效益,以养殖水体碱度维持在100 mg/L CaCO3为宜。     

"西藏雪莲"中乳酸菌的分离鉴定及发酵性能研究

将"西藏雪莲"转接纯化3次后对其进行整体切片镜检,并用加有CaCO3的鉴别性培养基,利用乳酸菌溶钙性产生透明圈将其与其他菌区分。所获得的乳酸菌进行分离纯化、鉴定,结果共鉴定出乳酸杆菌2株、双歧杆菌1株、乳酸球菌3株。最后对这些菌株的发酵性能进行测定,并进行组合发酵试验,从中获得人体有益菌和性能优良的乳酸复合发酵剂。     

石灰性土壤中固磷基质的探讨

本文对采自我国北方7省(区)的39个石灰性土样的8项基本性质(CaCO_3<0.01mm物理粘粒、<0.001mm粘粒、游离Fe_2O_3、pH、有机质、速效磷和全磷)进行了分析,并对其磷酸吸收系数(PAC)、固磷百分率和磷肥指数(PFI)作了测定,通过相关分析、通径分析和多元逐步回归分析表明,石灰性土壤的主要固磷基质是<0.01mm物理粘粒,而不是CaCO_3。