Direct reduction of zinc sulfide under vacuum

The present work is a continuation of the previous investigations of Gross and Warrington and Liu in which the effect of various reducing agents on the vacuum reduction of zinc sulfide was studied. The author became interested in this topic while reading the papers by these investigators in which they recommended that further work be performed in an attempt to prevent zinc sulfide from distilling over during reduction, thereby contaminating the zinc condensate. The original plan was to perform a few runs for the purpose of duplicating the results that were reported by Liu, and from this point carry on the work using reducing agents other than iron. Soon after the work had been started, it was found that the results of Liu for the reduction of zinc sulfide could not be duplicated, particularly at the lower reaction temperatures; therefore, the previously reported results were cast aside and a considerable amount of work was performed for two purposes: (1) to determine the reasons for the lack of agreement, and (2) to investigate thoroughly several of the operational variables in order that this work might be given more justification for being acceptable than the previous work by Liu. In addition to using several other reducing agents at various reaction temperatures and for specified times at temperature, experiments were made to determine the effect, if any, of the crucible shape and the degree of charge compaction on the recovery of metallic zinc. The latter phase of the work was concerned with an attempt to improve the zinc condensates that were produced in previous iron reduction runs by redistilling a carefully selected composite charge for various times at certain temperatures. It shall be seen that certain reducing agents were very effective in reducing zinc sulfide directly to metallic zinc; however, a portion of the sulfur in the charge also distilled into the condensing region as zinc sulfide. Moreover, the majority of the condensates that were produced were extracted either as a loose powder or as thin brittle sheets. Sometimes a suitable metallic sheet was produced, but only if a high reaction temperature was used. Therefore, the purpose for redistilling the condensates as a composite charge was twofold: (1) to improve the physical characteristics of the condensates by attempting to produce zinc as strong metallic sheets, and (2) to determine the extent of evaporation of sulfur as zinc sulfide from the composite and its effect on the purity of the resulting condensate --Introduction, pages 2-4

The April 29, 1965, Puget Sound earthquake and the crustal and upper mantle structure of western Washington

Simultaneous modeling of source parameters and local layered earth structure for the April 29, 1965, Puget Sound earthquake was done using both ray and layer matrix formulations for point dislocations imbedded in layered media. The source parameters obtained are: dip 70° to the east, strike 344°, rake −75°, 63 km depth, average moment of 1.4 ± 0.6 × 10^(26) dyne-cm, and a triangular time function with a rise time of 0.5 sec and falloff of 2.5 sec. An upper mantle and crustal model for southern Puget Sound was determined from inferred reflections from interfaces above the source. The main features of the model include a distinct 15-km-thick low-velocity zone with a 2.5-km/sec P-wave-velocity contrast lower boundary situated at approximately 56-km depth. Ray calculations which allow for sources in dipping structure indicate that the inferred high contrast value can trade off significantly with interface dip provided the structure dips eastward. The effective crustal model is less than 15 km thick with a substantial sediment section near the surface. A stacking technique using the instantaneous amplitude of the analytic signal is developed for interpreting short-period teleseismic observations. The inferred reflection from the base of the low-velocity zone is recovered from short-period P and S waves. An apparent attenuation is also observed for pP from comparisons between the short- and long-period data sets. This correlates with the local surface structure of Puget Sound and yields an effective Q of approximately 65 for the crust and upper mantle

Bioaccumulation surveillance in Milford Haven Waterway

Biomonitoring of contaminants (metals, organotins, PAHs, PCBs) was carried out along the Milford Haven Waterway (MHW) and at a reference site in the Tywi Estuary during 2007-2008. The species used as bioindicators encompass a variety of uptake routes - Fucus vesiculosus (dissolved contaminants); Littorina littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and Nereis diversicolor (omnivore which often reflects contaminants in sediment). Differences in feeding strategy and habitat preference have subtle implications for bioaccumulation trends though, with few exceptions, contaminant body burdens in Milford Haven (MH) were higher than those at the Tywi reference site, reflecting inputs. Elevated concentrations of metals were occasionally observed at individual MH sites, whilst As and Se (molluscs and seaweed) were, for much of MHW, consistently at the higher end of the UK range. However, for the majority of metals, distributions in MH biota were not exceptional by UK standards. Several metal-species combinations indicated increases in bioavailability at upstream sites, which may reflect the influence of geogenic or other land-based sources – perhaps enhanced by lower salinity (greater proportions of more bioavailable forms). TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi were close to zero. Phenyltins were not accumulated appreciably in Mytilus, whereas some Nereis populations may have been subjected to localized (historical) sources. PAHs in Nereis tended to be evenly distributed across most sites, but with somewhat higher values at Dale for acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and chrysene; naphthalenes tended to be enriched further upstream in the mid-upper Haven (a pattern seen in mussels for most PAHs). Whilst concentrations in MH mussels were mostly above reference site and OSPAR backgrounds, it is unlikely that ecotoxicological guidelines would be exceeded. PCBs in mussels were between upper and lower OSPAR guidelines and were unusual in their distribution in that highest levels occurred at the mouth of MH. Condition indices (CI) of bivalves (mussels and cockles) were highest at the Tywi reference site and at the seaward end of MH, decreasing upstream along the Waterway. There were a number of significant (negative) relationships between CI and body burdens and multivariate analysis indicated that a combination of contaminants could influence the pattern in condition (and sub-lethal responses such as MT and TOSC) across sites. Cause and effect needs to be tested more rigorously in future assessments

Waveform-level time-domain simulation comparison study of three shipboard power system architectures

Detailed waveform-level modeling and simulation of three alternative shipboard power system architectures is presented herein. The three system architectures are based on conventional 60Hz medium-voltage ac (MVAC), higherfrequency 240Hz medium-voltage ac (HFAC) and mediumvoltage dc (MVDC) technologies. To support the quantitative assessment and comparison of these three different power system architectures, each technology was modeled using a common representative, notional baseline ship. The baseline ship represents a multi-mission destroyer fitted with an 80MW next generation integrated power system (NGIPS). Modeling of each power system architecture is set forth along with simulation studies for three fault scenarios. Each of the three power system architectures was implemented within the MATLAB/ Simulink environment. Continuity of service was evaluated for each architecture along with a fault scenario using an operability metric. After a brief description of the three power system architectures and the operability metric, quantitative results are presented.Center for Electromechanic

Intersex related gene expression profiles in clams Scrobicularia plana : molecular markers and environmental application

Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction

Intersex in the clam Scrobicularia plana (Da Costa): Widespread occurrence in English Channel estuaries and surrounding areas

Estuarine clams Scrobicularia plana were sampled from 108 intertidal locations around the English Channel and adjacent areas. Although S. plana is believed to be a strict gonochorist, 58% of the populations sampled included intersexed individuals (described as male clams exhibiting ovotestis). Over the entire region, on average, 8.6% of male clams exhibited intersex, although proportions of affected males ranged from 0% to 53% depending on location. The severity of intersex was assessed using a simple classification scale, with the majority of individuals showing low levels of impact. Sex ratios were significantly skewed at some sites. There were no significant relationships between the incidence and severity of intersex; or of associations with size or parasitism of individual clams. Intersex in S. plana is a useful tool to assess endocrine disruptive effects in estuaries, although mechanisms of impact and causative agents remain uncertain

The International Lepidoptera Survey Newsletter, December 2007

Contents (pages 1-66) Title Flight Periods of California Butterflies for “Resident Species,” Subspecies and Most Strays to the State (2007) Authors Kenneth E. Davenport, Ray E. Stanford and Robert L. Langston Abstract Normal flight periods and early/late records for resident species, subspecies and regular strays of butterflies of California are presented below.. Many subspecies or populations in the state are distinctive and may prove to merit species recognition by specialists in the future

The International Lepidoptera Survey Newsletter, April 2005

Contents (pages 1-66) Title Flight Periods of California Butterflies for “Resident Species,” Subspecies and Most Strays to the State (2005) Authors Kenneth E. Davenport, Ray E. Stanford and Robert L. Langston Abstract Normal flight periods and early/late records for resident species, subspecies and regular strays of butterflies of California are presented below.. Many subspecies or populations in the state are distinctive and may prove to merit species recognition by specialists in the future