Advances in the use of recycled non-ferrous slag as a resource for non-ferrous metal mine site remediation

The growing global demand for non-ferrous metals has led to serious environmental issues involving uncovered mine site slag dumps that threaten the surrounding soils, surface waters, groundwater, and the atmosphere. Remediation of these slags using substitute cement materials for ordinary Portland cement (OPC) and precursors for alkali-activated materials (AAMs) can convert hazardous solid wastes into valuable construction materials, as well as to attain the desired solidification and stabilization (S/S) of heavy metal(loid)s (HM). This review discusses the current research on the effect of non-ferrous slags on the reaction mechanisms of the OPC and AAM. The S/S of HM from the non-ferrous slags in AAM and OPC is also reviewed. HM can be stabilized in these materials based on the complex salt effect and isomorphic effects. The major challenges faced in AAMs and OPC for HM stabilization include the long-term durability of the matrix (e.g., sulfate attack, stability of volume). The existing knowledge gaps and future trends for the sustainable application of non-ferrous slags are also discussed.

Biomonitoring and assessment of toxic element contamination in floodplain sediments and soils using fluorescein diacetate (FDA) enzymatic activity measurements: evaluation of possibilities and limitations through the case study of the Drava River floodplain

The EU Water Framework Directive requires the monitoring and evaluation of surface water sediment quality based on the assessment of risk posed by contamination on the biotic receptors. Floodplain sediments are important receptors of potentially toxic element (PTE) contamination from the upstream catchment areas, and floodplains host climate-sensitive riverine ecosystems and fertile agricultural areas at the same time. This study investigates the effect of PTE contamination on microbial communities in floodplain sediments and soils using the fast, inexpensive and reliable fluorescein diacetate (FDA) method in order to estimate its applicability for sediment quality monitoring and preliminary toxicity-based risk assessment. Sediment and soil samples were collected from the actively flooded alluvial plain and the river terrace areas along a 130-km stretch of the large Drava River floodplain known to be widely contaminated by historical mining, smelting and the associated industry in the upstream Alpine region. Results of detailed data analysis show that the total microbial activity represented by the measured FDA values is related to PTE (As, Cu, Zn, Cd, Pb) concentrations, but this relationship shows significant heterogeneity and depends on the spatial location and on the soil properties such as organic matter content, dissolved salt and nutrient content, and it is specific to the toxic elements. Results show that some microbe species appear to be able to adapt to the elevated PTE concentrations in toxic soil micro-environments, over time. Despite the observed heterogeneity of microbial activity, the results revealed a breakpoint in the FDA dataset around the FDA = 3 FC (fluorescein concentration) value suggesting that microbial activity is controlled by thresholds.

Effects of typical flotation reagent on microbial toxicity and nickel bioavailability in soil

The combined toxicological effects of nickel (Ni) and butyl xanthate (BX), that is commonly used in flotation reagents for non-ferrous metals ore processing such as Ni, copper and lead ores, on soil microbial communities were studied by determining soil microbial activity, soil enzyme activities and Ni bioavailability. The results revealed that the exchangeable (EXC) and reducible (RED) fractions of Ni were higher in Ni/BX mixture than Ni alone, probably because BX reacts with Ni to form complexes that lead an increase in bioavailability of Ni. The presence of BX and Ni inhibited microbial activity and enzyme activities during the first 30-days. Then, from 30 days to 180 days, different trends were observed according to the condition: microbial activity was stimulated with BX alone while it was inhibited with Ni/BX mixture. This observation was supported by the fact that the inhibitory ratio (I) was higher for Ni/BX mixture than BX alone. Results showed that the sensitivity to one or both contaminants followed the order: urease (UA) > invertase (INV). EXC fraction of Ni/BX mixture were significantly correlated with UA, INV, I, peak power (P_peak) and peak time (T_peak), respectively (p < 0.01), suggesting that Ni bioavailability might explain the Ni toxicity against microbial communities under combined pollution conditions. Such observations allow us to better understand toxic effects of Ni pollution when accompanied with BX, facilitating precisely evaluation of potential risks in mining areas.

Arundo donax L. stem-derived biochar increases As and Sb toxicities from nonferrous metal mine tailings

Toxic metal(loid)s released from tailing residues of mining operations have become a global issue with regard to environmental impacts. Biochar derived from the agriculture waste is considered as a cost-effective and stable material, which could be applied for remediation of sites contaminated with toxic metal(loid)s. In the present study, tailings were amended for 90 days with increasing concentrations of Arundo donax L. stem-derived biochar (ASBC; at 0, 1, 3, and 5%). The 7-day wheat seed germination toxicity test was then used to assess the bioavailability of toxicants in aqueous leachates of the biochar-amended tailing samples. Concentrations of As, Cd, Cu, Pb, and Sb in leachates and the Community Bureau of Reference chemical fractions were determined using ICP-OES. The results indicated that tailing leachates were phytotoxic, an effect that was partially decreased due to increasing concentrations of ASBC, with maximum effects (∼47% of tailing phytotoxicity) occurring at 3% ASBC. Results of further fractionation analyses indicated that increasing concentrations of ASBC amendment decreased the mobile fractions of Cd, Cu, and Pb in tailing samples, but increased the mobilities of As and Sb. A novel approach using the relative toxicity index (= sum of toxicities of individual potentially toxic elements) indicated that the toxicity of the tailings decreased when As was not present, since As decreased the biochar-reduced toxicity. Our results suggest that the ability of using biochar to decrease toxicity in tailings (by sequestration of cationic metals such as Cd, Cu, and Pb) is limited by its inability to immobilize oxyanionic metalloids such as As and Sb.

Spatial relationship between the field-measured ambient gamma dose equivalent rate and geological conditions in a granitic area, Velence Hills, Hungary: An application of digital spatial analysis methods

In order to estimate the annual dose that the public receive from natural radioactivity, the identification of the potential risk areas is required which, in turn, necessitates understanding the relationship between the spatial distribution of natural radioactivity and the geogenic risk factors (e.g., rock types, presence of dikes, faults, physical conditions of soil, etc.). A detailed spatial analysis of outdoor ambient gamma dose equivalent rate was performed in the western side of Velence Hills, the largest outcropped granitic area in Hungary. In order to assess the role of local geology in the spatial distribution of gamma dose rates, field measurements were carried out at ground level at 300 sites along a 250 m x 250 m regular grid in a total surface of 19.8 km². Digital image processing methods were applied to identify anomalies, heterogeneities and spatial patterns in the measured gamma dose rates, including local maxima and minima determination, digital cross sections, gradient magnitude and gradient direction, second derivative profile curvature, local variability, lineament density, 2D autocorrelation and directional variogram analyses. Statistical inference shows that different gamma dose rate levels are associated with the geological formations, with the highest level on the Carboniferous granite including outlying values. Moreover, digital image processing reveales that linear gamma dose rate spatial features are parallel to the SW-NE dike system and to the NW-SE main fractures. The results of this study underline the importance of understanding the role of geogenic risk factors influencing the ambient gamma dose equivalent rate received by public. The study also demonstrates the power of the image processing techniques for the identification of spatial pattern in field-measured geogenic radiation.

Microcalorimetry and enzyme activity to determine the effect of nickel and sodium butyl xanthate on soil microbial community

In non-ferrous metal tailings, combined pollution in the surrounding soil is caused by heavy metals and flotation chemicals. The combined effects of nickel (Ni) and its primary ore processing collector, sodium butyl xanthate (SBX), on soil microbial activity were investigated following the fluorescein diacetate hydrolase (FDA) and sucrase (SA) activities, and isothermal microcalorimetry during 60 days. FDA and SA activities as well as overall soil microbial activity were significantly affected by Ni, SBX and Ni/SBX mixture. The inhibition rate (I) of the growth rate constant (k) being higher with the Ni/SBX mixture than with SBX alone during the experiment. The growth rate constant (k) was positively correlated (p < 0.05 or p < 0.01) with enzyme activities (FDA and SA) indicating that k represented a valuable proxy to evaluate the toxic effect of metals and flotation reagents on soil microorganisms. Thus, microcalorimetry was a useful method to characterize soil microbial communities.

Combined effects of antimony and sodium diethyldithiocarbamate on soil microbial activity and speciation change of heavy metals. Implications for contaminated lands hazardous material pollution in nonferrous metal mining areas

The combined effects of antimony (Sb) and sodium diethyldithiocarbamate (DDTC), a common organic flotation reagent, on soil microbial activity and speciation changes of heavy metals were investigated for the first time. The results showed that the exchangeable fraction of Sb was transformed to a stable residual fraction during the incubation period, and the addition of DDTC promoted the transformation compared with single Sb pollution, probably because DDTC can react with heavy metals to form a complex. In addition, the presence of DDTC and Sb inhibited the soil microbial activity to varying degrees. The growth rate constant k of different interaction systems was in the following order on the 28th day: control group ≥ single DDTC pollution > combined pollution > single Sb pollution. A correlation analysis showed that the concentration of exchangeable Sb was the primary factor that affected the toxic reaction under combined pollution conditions, and it significantly affected the characteristics of the soil microorganisms. All the observations provide useful information for a better understanding of the toxic effects and potential risks of combined Sb and DDTC pollution in antimony mining areas.

Spatial analysis of ambient gamma dose equivalent rate data by means of digital image processing techniques

A detailed ambient gamma dose equivalent rate mapping based on field measurements at ground level and at 1 m height was carried out at 142 sites in 80 × 90 km area in Pest County, Hungary. Detailed digital image processing analysis was carried out to identify and characterise spatial features such as outlying points, anomalous zones and linear edges in a smoothed TIN interpolated surface. The applied method proceeds from the simple shaded relief model and digital cross-sections to the more complex gradient magnitude and gradient direction maps, 2nd derivative profile curvature map, relief map and lineament density map. Each map is analysed for statistical characteristics and histogram-based image segmentation is used to delineate areas homogeneous with respect to the parameter values in these maps. Assessment of spatial anisotropy is implemented by 2D autocorrelogram and directional variogram analyses. The identified spatial features are related to underlying geological and tectonic conditions using GIS technology. Results show that detailed digital image processing is efficient in revealing the pattern present in field-measured ambient gamma dose equivalent rates and they are related to regional scale tectonic zones and surface sedimentary lithological conditions in the study area.

Radon and thoron levels, their spatial and seasonal variations in adobe dwellings - a case study at the great Hungarian plain

Radon and thoron isotopes are responsible for approximately half of the average annual effective dose to humans. Although the half-life of thoron is short, it can potentially enter indoor air from adobe walls. Adobe was a traditional construction material in the Great Hungarian Plain. Its major raw materials are the alluvial sediments of the area. Here, seasonal radon and thoron activity concentrations were measured in 53 adobe dwellings in 7 settlements by pairs of etched track detectors. The results show that the annual average radon and thoron activity concentrations are elevated in these dwellings and that the proportions with values higher than 300 Bq m(-3) are 14-17 and 29-32% for radon and thoron, respectively. The calculated radon inhalation dose is significantly higher than the world average value, exceeding 10 mSv y(-1) in 7% of the dwellings of this study. Thoron also can be a significant contributor to the inhalation dose with about 30% in the total inhalation dose. The changes of weather conditions seem to be more relevant in the variation of measurement results than the differences in the local sedimentary geology. Still, the highest values were detected on clay. Through the year, radon follows the average temperature changes and is affected by the ventilation, whereas thoron rather seems to follow the amount of precipitation.

Mapping the geogenic radon potential: methodology and spatial analysis for central Hungary

A detailed geogenic radon potential (GRP) mapping based on field soil gas radon and soil gas permeability measurements was carried out in this study. A conventional continuous variable approach was used in this study for GRP determination and to test its applicability to the selected area of Hungary. Spatial pattern of soil gas radon concentration, soil permeability and GRP and the relationship between geological formations and these parameters were studied by performing detailed spatial analysis. Exploratory data analysis revealed that higher soil gas radon activity concentration and GRP characterizes the mountains and hills than the plains. The highest values were found in the proluvial-deluvial sediments, rock debris on the downhill slopes eroded from hills. Among the Quaternary sediments, which characterize the study area, the fluvial sediment has the highest values, which are also located in the hilly areas. The lowest values were found in the plain areas covered by drift sand, fluvioeolic sand, fluvial sand and loess. As a conclusion, radon is related to the sediment cycle in the study area. A geogenic radon risk map was created, which assists human health risk assessment and risk reduction since it indicates the potential of the source of indoor radon. The map shows that low and medium geogenic radon potential characterizes the study area in central Hungary. High risk occurs only locally. The results reveal that Quaternary sediments are inhomogeneous from a radon point of view, fluvial sediment has medium GRP, whereas the other rock formations such as drift sand, fluioeolic sand, fluvial sand and loess, found in the study area, have low GRP.

Dynamics of soil gas radon concentration in a highly permeable soil based on a long-term high temporal resolution observation series

This paper studies the temporal variation of soil gas radon activity concentration in a highly permeable (k = 2.0E-11 m(2)) sandy-gravelly soil in order to understand if temporal variation of soil gas radon activity concentration can affect geogenic radon potential determination. Geogenic radon potential provides information about the potential risk from radon. Its calculation takes into account the equilibrium, saturated at infinite depth, soil gas radon activity concentration (c∞). This concentration may vary at annual time scale due to the environmental conditions. A long-term (yearly) and high temporal resolution (15 min) observation, applied in this study, reveal various temporal features such as long-term trend, seasonality, daily periodicity and sudden events in soil gas radon time series. Results show seasonal and daily periodical variation of the measured soil gas radon activity concentration (csoilRn) in a highly permeable sandy-gravelly soil with definite seasons without obvious long transitional periods. The winter (from October 2010 to April 2011) is characterized by 2.5 times higher average soil gas radon activity concentration (median is 7.0 kBq m(-3)) than the summer (August, September 2010 and May, June, July 2011) (median is 2.8 kBq m(-3)). Daily periodicity, which is much less than the seasonal one, controls the soil gas radon activity concentration mainly in the summer season. Average (AM) value of csoilRn is higher at night than in the daytime with about 18% and 3.8% in summer and in winter, respectively. As a conclusion, in case of single csoilRn measurement on a highly permeable (k ≥ 2.0E-11 m(2)) soil, similar to our test site, csoilRn should be corrected according to the seasons for calculating the equilibrium activity concentration c∞ value.

Decision support methods for the environmental assessment of contamination at mining sites

Polluting mine accidents and widespread environmental contamination associated with historic mining in Europe and elsewhere has triggered the improvement of related environmental legislation and of the environmental assessment and management methods for the mining industry. Mining has some unique features such as natural background pollution associated with natural mineral deposits, industrial activities and contamination located in the three-dimensional sub-surface space, the problem of long-term remediation after mine closure, problem of secondary contaminated areas around mine sites and abandoned mines in historic regions like Europe. These mining-specific problems require special tools to address the complexity of the environmental problems of mining-related contamination. The objective of this paper is to review and evaluate some of the decision support methods that have been developed and applied to mining contamination. In this paper, only those methods that are both efficient decision support tools and provide a 'holistic' approach to the complex problem as well are considered. These tools are (1) landscape ecology, (2) industrial ecology, (3) landscape geochemistry, (4) geo-environmental models, (5) environmental impact assessment, (6) environmental risk assessment, (7) material flow analysis and (8) life cycle assessment. This unique inter-disciplinary study should enable both the researcher and the practitioner to obtain broad view on the state-of-the-art of decision support methods for the environmental assessment of contamination at mine sites. Documented examples and abundant references are also provided.

How do long-term development and periodical changes of river-floodplain systems affect the fate of contaminants? Results from European rivers

In many densely populated areas, riverine floodplains have been strongly impacted and degraded by river channelization and flood protection dikes. Floodplains act as buffers for flood water and as filters for nutrients and pollutants carried with river water and sediment from upstream source areas. Based on results of the EU-funded "AquaTerra" project (2004-2009), we analyze changes in the dynamics of European river-floodplain systems over different temporal scales and assess their effects on contaminant behaviour and ecosystem functioning. We find that human-induced changes in the hydrologic regime of rivers have direct and severe consequences on nutrient cycling and contaminant retention in adjacent floodplains. We point out the complex interactions of contaminants with nutrient availability and other physico-chemical characteristics (pH, organic matter) in determining ecotoxicity and habitat quality, and draw conclusions for improved floodplain management.

Neuroprotective effect of adenoviral-mediated gene transfer of TIMP-1 and -2 in ischemic brain injury

Gene therapy may be a promising approach for treatment of brain ischemia. We and others previously demonstrated that increased activity of matrix metalloproteinases (MMPs) contributes to the tissue damage that results from ischemic injury. The proteolysis of MMPs is tightly controlled by tissue inhibitors of MMPs (TIMPs). In this study, we examined whether adenoviral-mediated gene transfer of TIMP-1 and TIMP-2 could protect against neuronal damage induced by global cerebral ischemia in mice. An adenovirus expressing TIMP-1 or TIMP-2 (AdTIMP-1 or AdTIMP-2) or a control adenovirus (RAd60) or vehicle was injected into the striatum 3 days before transient global cerebral ischemia. The extent of neuronal damage was quantified 3 days post-ischemia. There was no significant difference in the extent of neuronal damage in vehicle as compared to RAd60-treated mice. In contrast, neuronal damage was reduced, by approximately 50%, after gene transfer of AdTIMP-1 (P<0.001) and AdTIMP-2 (P< 0.01) as compared to controls. This study provides the first in vivo evidence of the protective effects of TIMP-1 and TIMP-2 via gene transfer in global ischemia.

Evaluation of four airway training manikins as simulators for inserting the LMA Classictm*

Airway manikins have traditionally been used for teaching mask ventilation and tracheal intubation. There is an increasing need to use manikins for training in procedures such as insertion of the laryngeal mask airway. We have assessed four new airway training manikins (latest versions of the Airway Trainer (Laerdal, Norway), Airway Management Trainer (Ambu, UK), 'Bill 1' (VBM, Germany) and Airsim (Trucorp, Ireland)) as simulators for insertion of the LMA Classic laryngeal mask airway. Twenty volunteer anaesthetists inserted a size-4 laryngeal mask airway five times into each of the four manikins, in random order. Each insertion was assessed using objective and subjective tests. Subjective assessment varied widely but overall assessment indicated that the Airway Management Trainer was the poorest simulator for insertion of the laryngeal mask airway. The 'Bill 1' and Airsim manikins performed best as simulators for insertion of the laryngeal mask airway, although realistic ventilation with 'Bill 1' was not possible.

Color discrimination in carriers of color deficiency

Carriers of X-linked color vision deficiencies have previously been reported to exhibit mild abnormalities of color matching and discrimination. In a sample of 55 carriers of protan and deutan deficiencies and 55 age-matched normal controls, we measured chromatic discrimination along a red-green axis. We found that discrimination was impaired in the case of carriers of deutan deficiencies (which affect the middle-wave-sensitive cones of the retina), but was normal in the case of carriers of protan deficiencies (which affect the long-wave-sensitive cones). We argue that this result can be explained by the difference in the relative numbers of middle- and long-wave cones in heterozygous retinae: the imbalance of the two cone types is predicted to be much greater in the case of the deutan heterozygote than in the case of the protan heterozygote. In future studies it will be necessary to consider separately the two types of heterozygote.

A study of titanium release into body organs following the insertion of single threaded screw implants into the mandibles of sheep

BACKGROUND

Titanium is generally considered a safe metal to use in implantation but some studies have suggested that particulate titanium may cause health problems either at the site overlying the implant or in distant organs, particularly after frictional wear of a medical prosthesis. It was the purpose of this investigation to study the levels of dissemination of titanium from threaded screw type implants following placement of single implants in sheep mandibles.

METHOD

Twelve sheep were implanted with a single 10x3.75mm self-tapping implant for time intervals of one, four and eight to 12 weeks. Four unoperated sheep served as controls. Regional lymph nodes, lungs, spleens and livers were dissected, frozen and subsequently analysed by Graphite Furnace Atomic Absorption Spectroscopy.

RESULTS

Results associated with successful implants showed no statistically significant different levels of titanium in any organ compared to controls, although some minor elevations in titanium levels within the lungs and regional lymph nodes were noted. Two implants failed to integrate and these showed higher levels of titanium in the lungs (2.2-3.8 times the mean of the controls) and regional lymph nodes (7-9.4 times the levels in controls).

CONCLUSIONS

Debris from a single implant insertion is at such a low level that it is unlikely to pose a health problem. Even though the number of failed implants was low, multiple failed implants may result in considerably more titanium release which can track through the regional lymph nodes. Results suggest that sheep would be an excellent model for following biological changes associated with successful and failed implants and the effect this may have on titanium release.

A multi-institutional analysis of laparoscopic orchidopexy

OBJECTIVE

To combine and analyse the results from centres with a large experience of laparoscopy for the impalpable testis with small series, to determine the expected success rate for laparoscopic orchidopexy.

METHODS

A questionnaire was distributed to participating paediatric urologists; each contributor retrospectively reviewed the clinical charts for their cases of therapeutic laparoscopy for an impalpable testis, detailing 36 variables for each patient. The data were collated centrally into a computerized database. For inclusion, the testis was intra-abdominal (including 'peeping' at the internal ring) at laparoscopic examination, was not managed through an open approach and did not undergo orchidectomy. Three surgical groups were assessed, with success defined as lack of atrophy and intrascrotal position: group 1, primary laparoscopic orchidopexy; group 2, a one-stage Fowler-Stephens (F-S) orchidopexy; and group 3, a two-stage F-S orchidopexy.

RESULTS

Data were gathered from 10 centres in the USA, covering the period 1990-1999; 252 patients representing 310 testes were included and overall, 15.2% were lost to follow-up. There was no significant difference between success rates in the larger and smaller series. Atrophy occurred in 2.2% of 178 testes, 22.2% of 27 testes and 10.3% of 58 testes in groups 1-3, respectively. Testes were not in a satisfactory scrotal position in 0.6%, 7.4% and 1.7% of groups 1-3, respectively. The mean follow-up for each group was 7.7, 8.6 and 20.0 months, respectively. The overall success for all groups was 92.8% (97.2% group 1; 74.1% group 2; 87.9% group 3), with an atrophy rate of 6.1%.

CONCLUSION

Laparoscopic orchidopexy for the intra-abdominal testis, in both large and small series, can be expected to have a success rate higher than that historically ascribed to open orchidopexy. Within this series, single-stage F-S laparoscopic orchidopexy resulted in a significantly higher atrophy rate than the two-stage repair. However, when considering both F-S approaches, the laparoscopic approach gave greater success than previously reported for the same open approaches. Despite the weaknesses inherent in a retrospective unrandomized study, we conclude that laparoscopic orchidopexy is, if not the procedure of choice, an acceptable and successful approach to the impalpable undescended testicle.

The influence of diet and exercise on muscle and plasma glutamine concentrations

PURPOSE

This study examined the relationship between muscle glutamine, muscle glycogen, and plasma glutamine concentrations over 3 d of high-intensity exercise during which dietary carbohydrate (CHO) intake varied.

METHODS

Five endurance-trained men completed two exercise trials in randomized order, over a 14-d period. Each trial required subjects to perform 50 min of high-intensity continuous and interval exercise on three consecutive days while consuming a diet that provided 45% of the energy as CHO or a diet in which CHO provided 70% of the total energy. Four days of inactivity and consumption of a 55% CHO diet separated the two randomized trials. Menus and food were provided for the subjects and all food and drink consumed were weighed and recorded for later analysis. Before exercise on the first day of each trial, at the start of exercise on day 3 and on completion of exercise on day 3, muscle was biopsied from the vastus lateralis for the analysis of glutamine and glycogen concentrations. Venous blood was sampled before and twice after exercise on each day for the analysis of plasma glutamine and cortisol concentrations.

RESULTS

Mean plasma glutamine concentration was significantly higher during the 70% CHO exercise trial when compared with the 45% CHO trial (P < 0.05). Glycogen decreased by the same magnitude during both trials and there was no relationship between changes in plasma glutamine and changes in muscle glycogen concentration. Muscle glutamine concentration did not change in either trial.

CONCLUSIONS

These data suggest that the influence of carbohydrate intake upon the concentration of plasma glutamine is not mediated through the concentration of intramuscular glycogen.

A new type of hexaosmium boride cluster, H3Os6(CO)16B, that does not conform to electron counting rules

A new type of hexaosmium boride cluster, H3Os6(CO)16B, was produced in the thermolysis of H3Os3(CO)9(BCO). This complex is an 86 valence electron cluster, but the Os6 framework does not possess one of the geometries previously observed for Os6 clusters that have 86 valence electrons. [HOs6(CO)18]- and [Os6(CO)18]2- have octahedral frameworks while that of H2Os6(CO)18 is a face-capped square pyramid. The Os6 framework of H3Os6(CO)16B can be viewed as being derived from a pentagonal bipyramid that is missing one equatorial vertex. It contains an interior boron atom. Alternatively, it can be viewed like the 84 valence cluster Os6(CO)18 as either a bicapped tetrahedron, with a boron atom residing on the edge of the tetrahedron that is common to the capped faces, or a face-capped trigonal bipyramid, with the boron atom on an equatorial edge of the bipyramid that is also an edge of the capped face. H3Os6(CO)16B was characterized by 1H, and 11B, 13C NMR, IR, and mass spectroscopies and single-crystal X-ray diffraction analysis. The molecular structure was determined from two separate crystals. The analysis of each crystal yielded virtually identical structures, but their volumes differed by 36 A3 due to differences in packing in the unit cell. Data for crystal I of H3Os6(CO)16B: monoclinic P2(1/n), a = 9.954(2) A, b = 15.780(4) A, c = 16.448(3) A, beta = 91.07(1) degrees, Z = 4. Data for crystal II of H3Os6(CO)16B: monoclinic P2(1/n), a = 9.927(2) A, beta = 16.623(2) A, b = 16.0233(10) A, beta = 97.78(1) degrees, Z = 4.

Shift in Rayleigh matches after adaptation to monochromatic light of various intensities

The action spectrum for inducing a long-lasting protan shift in colour matches was investigated. Rayleigh matches were measured before and after 30 min adaptation to monochromatic light of 520, 550, 580 or 620 nm. For each wavelength, seven retinal illuminances, ranging from 3.0 to 5.0 log td, were chosen in random order. Results for one colour-normal observer show that the shift in Rayleigh match after adaptation increases monotonically as a function of the luminance of the adapting light. The dynamic response range is from 3.3 to 4.7 log td. The wavelength of the adapting light had no systematic influence on the form of the response function. The results imply that the effect is triggered by light absorbed in the photopigments themselves.

Maintenance of motor pattern phase relationships in the ventilatory system of the crab

The central pattern generator responsible for the gill ventilation rhythm in the shore crab Carcinus maenas can produce a functional motor pattern over a large (eightfold) range of cycle frequencies. One way to continue to generate a functional motor pattern over such a large frequency range would be to maintain the relative timing (phase) of the motor pattern as cycle frequency changes. This hypothesis was tested by measuring the phase of eight events in the motor pattern from extracellular recordings at different rhythm frequencies. The motor pattern was found to maintain relatively constant phase relationships among the various motor bursts in this rhythm over a large (sevenfold) range of cycle frequencies, although two phase-maintaining subgroups could be distinguished. Underlying this phase maintenance is a corresponding change in the time delay between events in the motor pattern ranging from 470 to 1800 ms over a sevenfold (300&shy;2100 ms) change in cycle period. Intracellular recordings from ventilatory neurons indicate that there is very little change in the membrane potential oscillation in the motor neurons with changes in cycle frequency. However, recordings from nonspiking interneurons in the ventilatory central pattern generator reveal that the rate of change of the membrane potential oscillation of these neurons varies in proportion to changes in cycle frequency. The strict biomechanical requirements for efficient pumping by the gill bailer, and the fact that work is performed in all phases of the motor pattern, may require that this motor pattern maintain phase at all rhythm frequencies.

Long-Term Changes in Colour Matching Functions after Exposure to Artificial Sunlight

We have previously reported that relatively short exposures (30 to 60 min) to either sunlight or artificial sunlight are sufficient to shift Rayleigh matches for several hours in the protan direction (1995 Investigative Ophthalmology and Visual Science36 392). We have subsequently found that this effect cannot be explained by either an alteration in (i) the orientation of photoreceptors, ie no change was found in Stiles — Crawford I before and after adaptation (1995 Perception24 Supplement, 11), or by an alteration in (ii) the density of an observer's macular pigment. In order to distinguish more generally between a change in a pre-receptoral filter and a change in the spectral sensitivity of M or L cones, we are currently obtaining colour matching functions between 570 and 620 nm. Measurements are made before and after 45-min exposure to a white field receiving an illumination of about 40 000 lux from an arc lamp. The mixture primaries are 550 and 690 nm set at 100 td. The stimulus field subtends 2 deg. Matches are made by a temporal substitution method and two staircases are randomly interleaved. The standard wavelengths are randomised.

Repair of obliterative vesicourethral stricture after radical prostatectomy: a technique for preservation of continence

We present the open surgical repair of complete obstruction of the bladder neck unresponsive to endoscopic management. By combining abdominal and perineal dissection, partial pubectomy, and omental wrapping, repeat anastomosis is possible without the need for bladder tubularization. Two patients have been repaired successfully. Although both men presented with indwelling suprapubic tubes and a defect of greater than 1.5 cm, they are now voiding normally at 18 and 7 months post-operatively without the need for pads, medication, or instrumentation. Complete obliteration of the bladder neck after radical prostatectomy can be functionally reconstructed. Postoperative continence will depend on the function of the membranous urethra. If incontinence occurs, this can be managed in a reconstructed open urethra.

Rayleigh matches and unique green

There are recurrent reports that Rayleigh matches are bimodally distributed in the colour-normal male population. Similar claims have been made for the distribution of the spectral locus of unique green. Moreover, a positive correlation has sometimes been reported between Rayleigh matches and unique green. Using a computer-controlled Maxwellian colorimeter and bias-free psychophysical methods, we measured both variables for 97 colour-normal male observers. We do not find a bimodal distribution either of Rayleight matches or of settings of unique green. Nor do we find any correlation between the two variables. However, we do observe a very significant relationship between the lightness of the subject's iris and the wavelength that he judges to be unique green.

[Problems of population in Tibet]

"The debate on Tibet's population and population issues is not a new one in the demographic literature. Drawing on the data of recent population censuses in China the author of the study gives a review of the problems. He uses documents--issued mostly in English--by means of which he can get a better insight into the reasons of the lack of data and into the assessment of the available data." (SUMMARY IN ENG)

A study of women heterozygous for colour deficiencies

We have examined the colour vision of 43 female subjects in the age range 30-59 yr of whom 31 were obligate carriers of various forms of colour deficiency and the rest were women who had no known colour-deficient relatives. In the case of all the carriers we established the phenotypes of their colour-deficient sons. As a group, carriers made significantly more errors on the Ishihara plates and showed enlarged matching ranges on the Nagel anomaloscope, but we could not replicate earlier reports of increased error scores on the Farnsworth-Munsell 100-Hue test or of systematic shifts in Rayleigh match mid-points. We did find that the colour matches of carriers of deuteranomaly were significantly displaced from those of normals in a ratio-matching task in which a mixture of 546 and 600 nm was matched with a mixture of 570 and 690 nm. Owing to X-chromosome inactivation, women who are heterozygous for anomalous trichromacy ought to have at least four types of cone in their retinae and we ask whether this affords them an extra dimension of colour vision, by analogy to New World monkeys where heterozygous females gain trichromacy in a basically dichromatic species. Many carriers of anomalous trichromacy exhibited no evidence for tetrachromacy, in that they accepted large-field Rayleigh matches following a rod bleach and they were unable to set unique matches in our ratio-matching task. However, eight carriers of anomalous trichromacy--and no other subject--refused large-field Rayleigh matches; and we found one carrier of deuteranomaly who was apparently able to make unique matches in the ratio-matching task.

The Nagel anomaloscope and seasonal variation of colour vision

In 1948 the German physicist, Manfred Richter, reported that colour vision has a seasonal variation. For four colour-normal subjects, he found a sinusoidal variation in the proportion of red and green required to match a monochromatic yellow, the equation known as the 'Rayleigh match'. In summer, subjects required more red in their mixture. The measurements were made with the Nagel anomaloscope, an instrument introduced in 1907 and which today, essentially unchanged, remains the definitive clinical instrument for classifying the many phenotypic variations in colour vision. The variation that Richter recorded in the red-green ratio was large (three Nagel units), and it now takes on fresh interest because it is comparable in size to the difference in Nagel settings later reported between normal observers of different genetic types. We have been able to replicate Richter's result, but report here that it is almost certainly instrumental: the Nagel anomaloscope proves to be very sensitive to ambient temperature.