Identification of complex aromatic molecules in individual interplanetary dust particles

Seventeen stratospherically collected particles-eight of which are classified as interplanetary dust particles (IDPs), seven of which are classified as probable terrestrial contaminants, and two of which have uncertain origins-were studied with a microprobe two-step laser mass spectrometer. Many polycyclic aromatic hydrocarbons(PAHs) and their alkylated derivatives were identified in two of the eight IDPs. The PAHs observed include a high-mass envelope not found in meteorites or terrestrial contaminants and prominent odd-mass peaks suggestive of nitrogen-containing functional groups attached to aromatic chromophores. In addition, the complexity of the IDP mass spectra has no precedence in previous studies of meteorite samples or their acid residues. Extensive checks were performed to demonstrate that the PAH signals are not caused by terrestrial contaminants.     

Acid dissolution experiments: carbonates and the 6.8-micrometer bands in interplanetary dust particles

A chemical dissolution experiment on an interplanetary dust particle (IDP) showed that carbonates, not acid-insoluble organic compounds, were responsible for virtually all the absorption at 6.8 micrometers seen in the infrared spectra of this particle. The IDP examined had an infrared spectrum characteristic of layer-lattice silicates and belongs to a class of IDP's whose spectra resemble those of protostellar objects like W33 A, which also exhibit a band at 6.8 micrometers.     

崇明金瓜种质资源鉴定及加工性状的综合评价

对收集的53份金瓜种质资源进行了鉴定,筛选13份优良种质材料,按金瓜加工性状评价标准,对瓜形、单瓜重、瓜皮色泽、成丝率、脆度等7个主要性状综合分析。结果表明：CM025、CM005、CM012的加工性状表现良好。     

Retention of Solar Helium and Neon in IDPs in Deep Sea Sediment

It was recently proposed that subduction of interplanetary dust particles (IDPs) contained in deep sea sediments could have introduced substantial solar helium and neon to the Earth's mantle. However, it is not certain if IDPs would retain solar noble gases during subduction. A diffusion experiment that examined He and Ne in IDPs in a magnetic separate from Pacific Ocean sediments showed that He and Ne would be lost from IDPs within 3 years at 500 degrees C, and possibly within 10(5) years at 200 degrees C, which suggests that they would be lost from subducting slabs at shallow depths.     

Reports refractory interplanetary dust particles

Criteria are described by which refractory interplanetary dust particles (IDPs) can be differentiated from the products of spacecraft debris. These criteria have been used to discover and characterize IDPs that are composed predominantly of refractory phases. Two of these particles contain hibonite, perovskite, spinel, refractory glass, and a melilite; only hibonite was identified within a third. The grain size for all particles ranges from 0.05 to 1 micrometer, so that they are much finer grained than the refractory calcium- and aluminum-rich inclusions in meteorites. The glass-containing refractory IDPs may be primitive nebular condensates that never completely crystallized and thus have been preserved extant.     

Interstellar polycyclic aromatic hydrocarbons and carbon in interplanetary dust particles and meteorites

Both interplanetary dust particles (IDP(s)) and meteorites may contain material that is similar to polycyclic aromatic hydrocarbons(PAH(s)). The Raman spectra of IDP(s) and meteorites show features that are similar in position and relative strength to interstellar infrared emission features that have been attributed to vibrational transitions in free, molecular-sized PAH(s). The Raman spectra of some IDP(s) also show red photoluminescence that is similar to the excess red emission seen in some astronomical objects and that has also been attributed to PAH(s) and hydrogenated amorphous carbon. Moreover, a part of the carbonaceous phase in IDP(s) and meteorites contains deuterium to hydrogen ratios that are greater than those for terrestrial samples. Deuterium enrichment is expected in small free PAH(s) that are exposed to ultraviolet radiation in the interstellar medium. Taken together, these observations suggest that some of the carbonaceous material in IDP(s) and meteorites may have been produced in circumstellar dust shells and only slightly modified in interstellar space.     

A carbonate-rich, hydrated, interplanetary dust particle: possible residue from protostellar clouds

Transmission electron microscopy of a hydrated interplanetary dust particle (IDP) indicates that it contains abundant magnesium-iron carbonates, primarily breunnerite and magnesian siderite. This IDP displays a strong absorption band at 6.8 micrometers in its infrared spectrum, similar to that in certain protostellar spectra. The carbonates probably account for the 6.8-micrometer band in the IDP spectrum, suggesting that carbonate also may occur in interstellar dust and be the source of the controversial 6.8-micrometer feature from the protostellar spectra.     

微生物接种对生活垃圾堆肥生化特性的影响

以生活垃圾为原料,利用静态堆肥反应装置,在通风好氧条件下,研究了接种微生物堆肥过程中温度、耗氧速率、CO2释放率以及几种酶活性变化规律。结果表明,与普通堆肥法(CK)比较,接种微生物菌剂堆肥(CM),可明显加速堆肥升温过程,延长高温阶段(55℃以上)24 h;堆肥中前期CM处理耗氧速率及CO2释放率显著增大,其峰值分别是CK处理的1.25、1.24倍;与CK处理比较,CM处理堆肥过程中纤维素酶、蔗糖酶、多酚氧化酶活性峰值分别增加了8.77%、8.30%和22.36%。结果显示,接种微生物可以明显改善生活垃圾堆肥过程中的生化特性。     

The fall, recovery, orbit, and composition of the Tagish Lake meteorite: a new type of carbonaceous chondrite

The preatmospheric mass of the Tagish Lake meteoroid was about 200,000 kilograms. Its calculated orbit indicates affinity to the Apollo asteroids with a semimajor axis in the middle of the asteroid belt, consistent with a linkage to low-albedo C, D, and P type asteroids. The mineralogy, oxygen isotope, and bulk chemical composition of recovered samples of the Tagish Lake meteorite are intermediate between CM and CI meteorites. These data suggest that the Tagish Lake meteorite may be one of the most primitive solar system materials yet studied.     

An astronomical 2175 angstrom feature in interplanetary dust particles

The 2175 angstrom extinction feature is the strongest (visible-ultraviolet) spectral signature of dust in the interstellar medium. Forty years after its discovery, the origin of the feature and the nature of the carrier(s) remain controversial. Using a transmission electron microscope, we detected a 5.7-electron volt (2175 angstrom) feature in interstellar grains embedded within interplanetary dust particles (IDPs). The carriers are organic carbon and amorphous silicates that are abundant in IDPs and in the interstellar medium. These multiple carriers may explain the enigmatic invariant central wavelength and variable bandwidth of the astronomical 2175 angstrom feature.     

促进农业废弃物腐解的复合微生物菌剂的筛选

以麦草和鸡粪作为腐解原料,用平板稀释法从土壤样品中分离纯化得到不同类型的微生物菌株,选择搭配优势群体培养成复合微生物菌剂,进行堆肥腐解试验。结果表明,微生物复合菌剂CM1和CM2能够有效增加麦草和鸡粪在固体发酵过程中的微生物数量,迅速提高发酵体的温度,降低鸡粪的臭气,从而促进麦草和鸡粪的腐解速度。     

秦川盆地土壤粘土矿物分析

用X射线粉晶衍射分析法研究了秦川盆地灰钙土、耕种灰钙土、沙田灰钙土、沙田盐化灰钙土、旱盐土5种土壤的粘土矿物组成。研究结果表明,5种土壤粘土矿物含量的平均值分别为1.14 %、1.18 %、1.78 %、0.72 %、2.26 %;秦川盆地5种主要土壤的粘土矿物组成是相似的,土壤粘土矿物以伊利石为主,其次为绿泥石,不含高岭石和蒙脱石以及由高岭石、蒙脱石与伊利石和绿泥石组成的混层粘土矿物;这反映秦川盆地的成土环境为碱性还原环境,说明土壤的发育程度比较低;粘土矿物随着土层深度的增加而增加,说明深层的风化程度较高,粘化作用较强,因而具有较高的土壤粘土矿物含量。     

抗根肿病大白菜材料SSR分子标记的初步筛选

为了明确抗根肿病大白菜材料CCR12049中的抗病基因,进一步开发分子标记。以高抗根肿病的高代自交系大白菜CCR12049、高感根肿病的高代自交系大白菜CM12081、CCR12049和CM12081杂交得到的F₁及F₁自交构建的F₂分离群体为试材,通过人工接种鉴定、聚丙烯酰胺凝胶电泳和序列比对。结果显示,该抗病材料中的根肿病抗性由显性单基因控制;36对引物在2个亲本和F₁中初步筛选出4对有多态性的引物,在F₂中进一步验证,发现只有1对(cr-26)在F₂中的扩增结果与表型鉴定一致;2个亲本及F₁的PCR产物测序比对发现,在95~111 bp这个位置,抗病亲本和F₁的序列完全相同,但是感病材料在这个位置出现了17个碱基(TCTCTATCTCTTACGCA)的缺失。可以推断抗病材料可能是由于这17个碱基的插入从而表现出抗病性,该标记可以将抗感材料区分开,该标记可以作为一个初步筛选白菜抗根肿病的SSR分子标记来利用。     

A nebular origin for chondritic fine-grained phyllosilicates

Hydrated minerals occur in accretionary rims around chondrules in CM chondrites. Previous models suggested that these phyllosilicates did not form by gas-solid reactions in the canonical solar nebula. We propose that chondrule-forming shock waves in icy regions of the nebula produced conditions that allowed rapid mineral hydration. The time scales for phyllosilicate formation are similar to the time it takes for a shocked system to cool from the temperature of phyllosilicate stability to that of water ice condensation. This scenario allows for simultaneous formation of chondrules and their fine-grained accretionary rims.     

Simplify the interpretation of alert lists for clinical mastitis in automatic milking systems

Based on sensor measurements, an automatic milking system (AMS) generates mastitis alert lists indicating cows which are likely to have clinical mastitis (CM). Because of the general assumption of equal probabilities of developing CM for all cows, all alerts on the list have the same success rate. As a consequence, it is not possible to rank-order the alerts in terms of their likelihood of CM. In practice, the performance of a CM detection system is not only based on the sensitivity (SN) and specificity (SP) of the system, but is also influenced by the prior probability of a cow having CM. This study illustrates the idea of using cow-specific prior probabilities of CM, based on non-AMS information, to provide a rank-order on the alerts from an AMS. A tree-augmented naive Bayesian network was trained from available data to determine these cow-specific prior probabilities for CM. The graphical structure of the network and the probability tables for its variables in the network were based on data from 274 Dutch dairy herds that recorded each case of CM over an 18-month period. The final data set contained information on a total of 5363 CM cases derived from 28,137 lactations and 22,860 cows. The available prior cow information (parity, days in milk, season of the year, somatic cell count history and CM history) was included as variables in the network. By combining the cow-specific prior probabilities of CM with the SN and SP of the detection system of the AMS, the computed success rates can be used to discriminate between CM alerts. Our illustrations indicate that the success rate might range from 3 to 84%, while assuming an equal overall probability would result in a success rate of 21%. Using the computed success rates, the CM alerts on an alert list can be rank-ordered, thereby providing the dairy farmer information about which cows have the highest priority for visual inspection for CM.     

腐植酸尿素与复合微生物菌剂配施对番茄产量和品质的影响

研究了2种新型肥料腐植酸尿素(HAN)、复合微生物菌剂(CM)配施对番茄产量、品质等的影响,以期为这2种新型肥料在蔬菜上的大面积推广应用提供依据。结果表明,在番茄上单独施用HAN处理比施用普通尿素处理增产2.83%;HAN+CM、HAN+PK(磷钾肥)、HAN+CM+PK处理比单独施用HAN处理增产1.65%~7.50%,且HAN+CM+PK处理产量最高,为56 700 kg/hm2;施肥不利于番茄Vc含量的增加,与单独施用尿素处理相比,施用HAN并配施CM可以提高番茄Vc含量;与其他处理相比,HAN+CM处理番茄可溶性糖含量最高,为1.15 mg/kg,而硝酸盐含量最低,只有1.83 mg/kg。可见,HAN与CM配施比单独施用尿素更有利于提高番茄产量、改善番茄品质。     

非金属矿物材料处理含磷废水的研究现状

介绍了膨润土、凹凸棒石、沸石、硅藻土、蛭石等非金属矿物材料的结构和性质,对其在含磷废水中的应用现状进行了综述,并对其应用前景进行了展望。     

条件培养基对昆虫细胞BTI-Tn5B1-4及克隆株特性的影响

研究了条件培养基对细胞BTI-Tn5B1-4及其克隆株特性的影响。用含20%条件培养基以2×105cells/ml浓度测定细胞生长曲线,并与新鲜培养基作比较。结果显示,含条件培养基的细胞培养中的最大浓度比对照培养基的浓度高,同时细胞群体倍增时间比对照培养基中缩短3～5小时。当用野生型病毒AcMNPV感染时,两种培养基中细胞敏感性均在93%以上,OB产量差异不显著。重组蛋白半乳糖苷酶和碱性磷酸酶表达量测定比较,结果显示条件培养基中两种重组蛋白表达量均比对照培养基中高大约10%。     

辣椒抗疫病相关基因的RGA STS标记的开发

利用西北农林科技大学园艺学院辣椒课题组克隆的辣椒抗疫病相关的全长基因RGA1(GenBank登录号:GQ386945)设计一对引物,上游引物为BY32,下游引物为RBQC-R。以对辣椒疫病高抗的品种CM334和感病品种EC为试材,利用PCR技术分析辣椒抗疫病的Sequence Tagged Sites(STS)标记。结果表明,在高抗品种CM334中得到700 bp大小的STS700标记,而在感病品种EC中未扩增出相应大小的片段。在多个不同抗疫病辣椒品种中验证说明,STS700标记鉴定辣椒疫病抗性可靠、稳定。     

Samples of stars beyond the solar system: silicate grains in interplanetary dust

We have identified six circumstellar silicate grains within interplanetary dust particles (IDPs). Their extrasolar origins are demonstrated by their extremely anomalous oxygen isotopic compositions. Three 17O-rich grains appear to originate from red giant or asymptotic giant branch stars. One 16O-rich grain may be from a metal-poor star. Two 16O-poor grains have unknown stellar sources. One of the grains is forsterite, and two are amorphous silicate "GEMS" (glass with embedded metal and sulfides), which is consistent with astronomical identifications of crystalline and amorphous silicates in the outflows of evolved stars. These observations suggest cometary origins of these IDPs and underscore the perplexing absence of silicates among circumstellar dust grains from meteorites.