Ascidian specimens were collected from the Indian River Lagoon, Florida, USA, in November 1987. Eudistoma olivaceum (Van Name) was fouled by only two species of epifaunal invertebrates and the percent cover of epibionts was negligible. Colonies of E. capsulatum (Van Name) were fouled by up to 17 species of epifaunal invertebrates, epibionts covered an average of 12.5% of the surface area of these colonies. Extracts of E. olivaceum exhibited potent cytotoxic, antimicrobial and antiviral activity in laboratory bioassays, while the activity of extracts of E. capsulatum was insignificant. The toxicity of extracts of each ascidian was negatively related to the percent cover of fouling organisms. Surface acidity of each ascidian was positively related to the percent cover of epibionts: E. olivaceum was nearly neutral (pH=6), while E. capsulatum was highly acidic (pH=1 to 2). Larval settlement and growth of ancestrulae of the cheilostome bryozoan Bugula neritina (Linnaeus) were inhibited at very low concentrations of crude extract of E. olivaceum. Crude extracts of E. capsulatum inhibited settlement and growth of B. neritina only at concentrations of approximately an order of magnitude greater than those of E. olivaceum. Differences in the degree to which these congeneric ascidians are fouled is related to differences in the chemical defenses they possess. Acidity is not an effective inhibitor of settlement by epifaunal invertebrates. 相似文献
By discussing “families” of moral emotions, we synthesize and review the moral emotions literature in an effort to advance organizational scholarship. First, we broadly discuss “what constitutes a moral emotion?” Second, we critically examine each family of moral emotions. We discuss key controversies and debates, particularly in terms of construct overlap, and provide recommendations. Third, we review scholarly work on each family of moral emotions in the workplace and offer ideas for future research. Finally, in our general future directions, we discuss a range of theoretical perspectives that can be used to advance the moral emotions literature in the management field. 相似文献
In utero sonographic diagnoses from forty-five malformed infants were correlated with their autopsy findings. Fifty-two malformations were diagnosed prenatally in 42 of the patients but 90 additional malformations were not. Nine sonographically diagnosed abnormalities were not confirmed at autopsy. Factors compromising sonographic diagnosis included: limited examinations, small fetal size, timing of examination, oligohydramnios, fetal position, nature of the malformation and unfamiliarity of the ultrasonographer with specific malformation syndromes. In vitro ultrasonography is an invaluable tool of diagnosing congenital malformations but has limitations. 相似文献
Cordylanthus palmatus is a hemiparasitic annual of the family Scrophulareacae. It is on both the federal and state lists of endangered species.
Only four widely separated populations remain, all of them in alkali sinks, where the plant thrives in saline-sodic soils.
The largest population is at Springtown, Alameda County, California. This article reports on efforts to develop a management
plan for both the plant and the alkali sink ecosystem. The plan is based on: (1) characterization of hydrology, soils and
geomorphology of the site; (2) characterization of the land use impacts to the site; (3) analysis of plant distribution in
relation to gradients of elevation and soil chemistry; (4) studies on water potential and water stress inCordylanthus palmatus and associated species. On the basis of this plan, both the State of California and private groups are cooperating to create,
restore, and manage a preserve in the Springtown Alkali Sink. 相似文献
A polyphasic approach based on cultivation and direct recovery of 16S rRNA gene sequences was utilized for microbial characterization of an aquifer contaminated with chlorinated ethenes. This work was conducted in order to support the evaluation of natural attenuation of chlorinated ethenes in groundwater at Area 6 at Dover Air Force Base (Dover, DE). Results from these studies demonstrated the aquifer contained relatively low biomass (e.g. direct microscopic counts of < 10(7) bacteria/g of sediment) comprised of a physiologically diverse group of microorganisms including iron reducers, acetogens, sulfate reducers, denitrifiers, aerobic and anaerobic heterotrophs. Laboratory microcosms prepared with authentic sediment and groundwater provided direct microbiological evidence that the mineralization of vinyl chloride and cis-dichloroethene as well as each step in the complete reductive dechlorination of tetracloroethene to ethene can occur in the Area 6 aquifer. Enrichment cultures capable of the oxidative degradation of cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) were obtained from groundwater across the aquifer demonstrating the possible importance of direct, non-cometabolic oxidation of cis-DCE and VC in natural attenuation. Culture-independent analyses based upon recovery of 16S rRNA gene sequences revealed the presence of anaerobic organisms distributed primarily between two major bacterial divisions: the delta subdivision of the Proteobacteria and low-G + C gram positive. Recovery of sequences affiliated with phylogenetic groups containing known anaerobic-halorespiring organisms such as Desulfitobacterium, Dehalobacter, and certain groups of iron reducers provided qualitative support for a role of reductive dechlorination processes in the aquifer. This molecular data is suggestive of a functional linkage between the microbiology of the site and the apparent natural attenuation process. The presence and distribution of microorganisms were found to be consistent with a microbially driven attenuation of chlorinated ethenes within the aquifer and in accord with a conceptual model of aquifer geochemistry which suggest that both reductive and oxidative mechanisms are involved in heterogeneous, spatially distributed processes across the aquifer. 相似文献
This article presents a case study of an accelerated cleanup conducted by EPA at the Adams Plating Company (APC) Superfund site near Lansing, Michigan. The APC site remediation was a Superfund EPA-lead project under the remedial program in Region 5. An accelerated cleanup was possible at the APC site by consistently identifying, evaluating, and implementing opportunities to streamline the remedial investigation (RI) and remedial design (RD) process. Streamlining opportunities were discovered and implemented in both the technical and administrative aspects of the project. Streamlining components used to accelerate the remedial process included: (1) extensive use of field screening techniques during the Phase II RI; (2) a focused feasibility study (FS) that evaluated only practical alternatives; (3) maintaining project momentum by initiating the RD concurrent with the issuance of the Record of Decision (ROD); (4) a highly accelerated RD with limited predesign work; (5) elimination of the transition period between RD and remedial action (RA) project phases; (6) frequent and effective communication, coordination, and cooperation between all parties involved (EPA, Michigan Department of Natural Resources (MDNR), technical contractor, PRC Environmental Management, Inc. (PRC), and the public); (7) maintaining a consistent project team throughout project duration; and (8) the setting of aggressive project goals. 相似文献
Polylactic acid (PLA) and thermoplastic starch (TPS) are biodegradable polymers of biological origin, and the mixture of these polymers has been studied due to the desirable mechanical properties of PLA and the low processing cost of TPS. However, the TPS/PLA combination is thermodynamically immiscible due to the poor interfacial interaction between the hydrophilic starch granules and the hydrophobic PLA. To overcome these limitations, researchers studied the modification, processing, and properties of the mixtures as a strategy to increase the compatibility between phases. This review highlights recent developments, current results, and trends in the field of TPS/PLA-based compounds during the last two decades, with the main focus of improving the adhesion between the two components. The TPS/PLA blends were classified as plasticized, compatible, reinforced and with nanocomposites. This article presents, based on published research, TPS/PLA combinations, considering different methods with significant improvements in mechanical properties, with promising developments for applications in food packaging and biomedicine.