三七药理作用的研究进展

目的研究石灰与Cd²⁺复合处理条件下,三七生物量和Cd含量及累积特征。方法开展田间小区试验,测定不同石灰施用量[0 (CK)、750和1 500 kg/hm²]、Cd²⁺(0、0.6、3.0、6.0、9.0和12.0 mg/kg)处理条件下,土壤pH、土壤有效态镉含量、三七生物量、Cd含量等指标。结果(1)随石灰施用量的增加,土壤pH升高,土壤中有效态镉含量显著降低。当石灰施用量为1 500 kg/hm²时,与CK相比,有效态镉含量显著降低(P<0.05),降低幅度为9.2%~38.1%。(2)在1 500 kg/hm²石灰和3.0mg/kg Cd²⁺处理下,三七主根、茎叶和总生物量分别比CK增加了74.4%、41.4%和31.1%。(3)在Cd²⁺为3.0、6.0、9.0和12.0 mg/kg时,施加1 500 kg/hm²石灰与CK相比,主根中Cd含量显著降低了13.0%、5.8%、13.2%和17.6% (P<0.05);在Cd²⁺为6.0、9.0、12.0 mg/kg时,施加1 500 kg/hm²石灰与CK处理相比,茎叶中Cd含量显著降低了13.6%、12.4%、20.8% (P<0.05)。结论施加石灰可以显著提高土壤pH (P<0.05),降低土壤中有效态镉含量,减少三七对Cd的吸收累积,增加三七生物量。     

Deep-Sea Microorganisms: In situ Response to Nutrient Enrichment

After inoculation of sterile organic materials on the deep-sea floor and in situ incubation for 1 year, relatively minute rates of microbial transformation were recorded. This extremely slow conversion rate, as well as the type and quantity of organic matter normally reaching the ocean floor, appear to characterize microbial life in the deep sea.     

In situ measurements of chemical distributions in a deep-sea hydrothermal vent field

Large changes in the concentration of sulfide around a hydrothermal vent in the Galápagos Rift provide direct evidence for the consumption of sulfide by the organisms of the vent community. These changes were detected with a new chemical analyzer capable of measuring silicate, sulfide, oxygen, and temperature on the sea floor at depths of 2500 meters. More than 10,000 measurements showed systematic variations in the sulfide and oxygen concentrations due to biogenic oxidation of sulfide in the hydrothermal solutions. Silicate concentration was highly correlated with temperature, but different trends were observed at different locations.     

多金属污染农田土壤固化／稳定化修复研究进展

固化／稳定化剂修复农田土壤重金属污染简单易行、成本低廉且不破坏土壤结构,但不同的固化／稳定化剂对土壤、作物及重金属离子的修复效果各不相同。文章概述了几种固化／稳定化剂的修复效果及优缺点,探讨了固化,稳定化修复重金属污染的作用机制以及影响重金属固化／稳定化修复效果的主要因素,分析了固化／稳定化修复农田土壤重金属污染的局限性,并从不同角度提出了今后的发展方向。     

Respiration of Benthopelagic Fishes: In situ Measurements at 1230 Meters

The respiration rate in situ of two common benthopelagic fishes, Coryphaenoides acrolepis and Eptatretus deani, was monitored at 1230 meters in the San Diego Trough. The respiration rate of C. acrolepis was two orders of magnitude lower and that of E. deani was significantly lower (P < .05) than rates in comparable shallow-water species.     

In situ observations of a high-pressure phase of H2O Ice

A previously unknown solid phase of H2O has been identified by its peculiar growth patterns, distinct pressure-temperature melting relations, and vibrational Raman spectra. Morphologies of ice crystals and their pressure-temperature melting relations were directly observed in a hydrothermal diamond-anvil cell for H2O bulk densities between 1203 and 1257 kilograms per cubic meter at temperatures between -10 degrees and 50 degreesC. Under these conditions, four different ice forms were observed to melt: two stable phases, ice V and ice VI, and two metastable phases, ice IV and the new ice phase. The Raman spectra and crystal morphology are consistent with a disordered anisotropic structure with some similarities to ice VI.     

In situ detection of beta-galactosidase in lenses of transgenic mice with a gamma-crystallin/lacZ gene

Transgenic mice carrying the gamma 2-crystallin promoter fused to the coding region of the bacterial lacZ gene were generated. The offspring of three founder mice expressed high levels of the enzyme solely in the central nuclear fiber cells of the lens as measured by an in situ assay for the detection of beta-galactosidase activity. These results suggest that gamma 2-crystallin sequences between -759 to +45 contain essential information required for appropriate tissue-specific and temporal regulation of the mouse gamma 2-crystallin gene. In a broader context, this study also demonstrates the utility of beta-galactosidase hybrid gene constructs for monitoring the activity of gene regulatory elements in transgenic mice.     

Dehalogenation: a novel pathway for the anaerobic biodegradation of haloaromatic compounds

Microorganisms of lake sediment and sewage sludge anaerobically metabolized halobenzoates by a novel pathway. The primary degradative event was loss of the aryl halide without the alteration of the aromatic ring. Dehalogenation required strict anaerobic conditions and depended on the halogen and position, but not the number of halogen substituents. A stable methanogenic bacterial consortium was enriched from sludge and found capable of dehalogenating and often mineralizing a variety of halobenzoates to CH(4) and CO(2). The results suggest that reductive dehalogenation of aromatics could be important in removal of some chlorinated xenobiotics from the environment.     

In situ discovery of graphite with interstellar isotopic signatures in a chondrule-free clast in an L3 chondrite

Optical and scanning electron microscopy of a chondrule-free clast in the unequilibrated L3 chondrite Khohar revealed a spherical object consisting of an aggregate of small ( approximately 2- micrometer diameter), Ni-poor (0.5 to 2.89 weight percent) metal particles and fine-grained graphite (<1-micrometer diameter). The graphite has large D and 15N excesses (deltaD approximately 1500 per mil and delta15N approximately 1300 per mil) with two isotopically distinct signatures: N rich with a high D/H ratio and N poor with a high 15N/14N ratio. These excesses are the largest D and 15N excesses observed in situ in a well-characterized phase in a meteorite. The isotopic characteristics are suggestive of an interstellar origin, probably by ion-molecule reactions at low temperature in the interstellar molecular cloud from which the solar system formed. The structure and nonchondritic composition of the metal particles suggest they did not form under equilibrium conditions in the solar nebula.     

适合植物组织原位杂交和原位PCR的切片制作

随着生物技术的不断发展,原位杂交技术与原位PCR技术在植物方面也有所进展.本文介绍了适合植物组织原位杂交和原位PCR的石蜡切片和冰冻切片的制备.     

In situ stable isotope probing of methanogenic archaea in the rice rhizosphere

Microorganisms living in anoxic rice soils contribute 10 to 25% of global methane emissions. The most important carbon source for CH4 production is plant-derived carbon that enters soil as root exudates and debris. Pulse labeling of rice plants with 13CO2 resulted in incorporation of 13C into the ribosomal RNA of Rice Cluster I Archaea in the soil, indicating that this archaeal group plays a key role in CH4 production from plant-derived carbon. This group of microorganisms has not yet been isolated but appears to be of global environmental importance.     

In situ studies of chemistry and structure of materials in reactive environments

Most materials and devices typically operate under specific environmental conditions, many of them highly reactive. Heterogeneous catalysts, for example, work under high pressure of reactants or in acidic solutions. The relationship between surface structure and composition of materials during operation and their chemical properties needs to be established in order to understand the mechanisms at work and to enable the design of new and better materials. Although studies of the structure, composition, chemical state, and phase transformation under working conditions are challenging, progress has been made in recent years in the development of new techniques that operate under a variety of realistic environments. With them, new chemistry and new structures of materials that are only present under reaction conditions have been uncovered.     

Non-GMO vs organic labels: purity or process guarantees in a GMO contaminated landscape

Since 2010, demand for non-GMO food products has grown dramatically. Two non-GMO labels dominate the market: USDA Organic and the Non-GMO Project Verified (the Project). However, the non-GMO status of Organic is not obvious from the label and many consumers are unaware of this. As sales of products carrying the Project’s non-GMO label have exploded, concern has increased among some Organic proponents that demand for non-GMO threatens the organic market. In response, both sides are seeking to build legitimacy and authority for their label by emphasizing the value of their standards for determining a food product’s non-GMO status within a GMO contaminated agrifood system. Drawing on in-depth interviews with key informants with knowledge of non-GMO standards and labels, we examine the knowledge systems, discourses and actors that proponents of the Project and USDA Organic privilege in their effort to legitimize their standards. Here, the Project emphasizes its application of technoscientific norms, especially thresholds and testing, which they argue provide the best means for preventing GMO contamination and helping consumers find (relative) non-GMO ‘purity’. In contrast, proponents of Organic favor a process standard that excludes GMOs, arguing that non-GMO ‘purity’ is unrealistic in today’s agrifood system that is widely contaminated by GMOs and where mandatory testing would unnecessarily harm organic producers. We conclude that tensions between the two groups are unlikely to be easily reconciled since these two distinct marketing labels rely on different knowledge and verification claims to vie for consumers and increase market share.     

In situ Sampler for Marine Sedimentary Pore Waters: Evidence for Potassium Depletion and Calcium Enrichment

A device for sampling the interstitial waters of deep-sea sediments in situ has been developed and tested. The sampler collects a series of samples over a depth of 1.5 meters in the sediment and thus makes possible the accurate delineation of chemical gradients existing in the pore waters. Samples collected in the North Atlantic indicate that significant gradients of K(+) and Ca(2+) exist in the sediments sampled. Interstitial solutions sampled between Ireland and Cape Cod, Massachusetts, are characterized by the depletion of K(+) and the enrichment of Ca(2+).     

Venus Thermosphere: In situ Composition Measurements, the Temperature Profile, and the Homopause Altitude

The neutral mass spectrometer on board the Pioneer Venus multiprobe bus measured composition and structral parameters of the dayside Venus upper atmosphere on 9 December 1978. Carbon dioxide and helium number densities were 6 x 10(6) and 5 x 10(6) per cubic centimeter, respectively, at an altitude of 150 kilometers. The mixing ratios of both argon-36 and argon-40 were approximately 80 parts per million at an altitude of 135 kilometers. The exospheric temperature from 160 to 170 kilometers was 285 +/- 10 K. The helium homopause was found at an altitude of about 137 kilometers.     

Migration of ruthenium-106 in a nevada test site aquifer: discrepancy between field and laboratory results

Ruthenium-106 has been observed to migrate in ground water at about the same velocity as tritium from the site of an underground nuclear explosion to a pumped satellite well 91 meters distant. This finding contradicts the prediction, based on laboratory batch sorption measurements, that ruthenium-106 should migrate at a much lower rate than tritium. To predict migration of radionuclides in ground water, more relevant laboratory measurements are required.