Height, frequency and spatial differentiation of atmospheric precipitation of the summer season for the period 1975-1982 are presented. Results of the respective investigations are compared with atmospheric precipitation in other areas of the western coast of Spitsbergen.
Measurements of pollutants scavenged from air masses over southern Svalbard in summer precipitation are presented. Rainfall was sampled in July and August 2002 at Calypsobyen, Bellsund. Specific conductivity (SpC) and pH were measured and ion concentrations were determined by ion chromatography. Ions of marine origin were subtracted, assuming that all chlorides were of marine origin. The FLEXTRA trajectory model was applied to discover the sources of air masses arriving at Svalbard and track the paths of pollutant transport. Average (v/w) rainfall pH was 4.94, mean SpC amounted to 34.8 µS cm-1. Total dissolved solids concentration (TDS) ranged from 12.6 to 67 mg L-1, with ions of marine origin (Cl-, Na+, Mg2+) prevailing. Rains with the highest percentage of marine salts occurred with winds from the East at above average velocities. Non-sea salt (nss) sulphate concentrations ranged from 0.5 µeq L-1 to 23 µeq L-1, (v/w) average was 17 µeq L-1. Nitrate concentrations ranged from 0 to 24 µeq L-1. The highest concentrations of nss-SO42- and NO3- were measured on 25 August, when the highest rainfall occurred (27 mm) and pH was the lowest (4.65). Rainfall at Calypsobyen deposited 194 kg km-2 of acidifying anions and 263 kg km-2 of base cations over the recording period. The polluted air masses were mostly from northern and central Europe. Rainfalls scavenging air masses formed over Greenland and Norwegian Seas displayed similar concentrations, being probably polluted by SOx and NOx from ship emissions.
The high mechanical properties of the Al-Li-X alloys contribute to their increasingly broad application in aeronautics, as an alternative forthe aluminium alloys, which have been used so far. The aluminium-lithium alloys have a lower specific gravity, a higher nucleation andcrack spread resistance, a higher Young’s module and they characterize in a high crack resistance at lower temperatures. The aim of theresearch planned in this work was to design an aluminium alloy with a content of lithium and other alloy elements. The research includedthe creation of a laboratorial melt, the microstructure analysis with the use of light microscopy, the application of X-ray methods to identify the phases existing in the alloy, and the microhardness test.
The paper presents the research results of the influence of the precipitation hardening on hardness and microstructure of selected Al-Si and Al-Cu alloys obtained as 30 mm ingots in a horizontal continuous casting process. The ingots were heat treated in process of precipitation hardening i.e. supersaturation with subsequent accelerated or natural ageing. Moreover in the range of the study it has been carried out investigations of chemical constitution, microscopic metallographic with use of scanning electron microscope with EDS analysis system, and hardness measurements using the Brinell method. On basis of obtained results it has been concluded that the chemical constitution of the investigated alloys enables to classify them into Al alloys for the plastic deformation as EN AW-AlSi2Mn (alternatively cast alloy EN AC-AlSi2MgTi) and as EN AW-AlCu4MgSi (alternatively cast alloy EN AC-AlCu4MgTi) grades. Moreover in result of applied precipitation hardening has resulted in the precipitation from a supersaturated solid solution of dispersive particles of secondary phases rich in alloying element i.e. Si and Cu respectively. In consequence it has been obtained increase in hardness in case of AlSi2Mn alloy by approximately 30% and in case of AlCu4MgSi alloy by approximately 20% in comparison to the as-cast state of continuous ingots.
Because of excellent properties, similar to natural bone minerals, and variety of possible biomedical applications, hydroxyapatite (HAp) is a valuable compound among the calcium phosphate salts. A number of synthesis routes for producing HAp powders have been reported. Despite this fact, it is important to develop new methods providing precise control over the reaction and having potential to scale-up. The main motivation for the current paper is a view of continuous synthesis methods toward medical application of produced hydroxyapatite, especially in the form of nanoparticles.
The scope of this work is to investigate the precipitation of two Al-Mg-Si alloys with and without Cu and excess Si by using the differential scanning calorimetry (DSC), transmission electron microscopic (TEM), Vickers hardness measurement and X-ray diffraction. The analysis of the DSC curves found that the excess Si accelerate the precipitation and the alloy contain the excess Si and small addition of copper has higher aging-hardness than that of free alloy (without excess Si and Cu) at the same heat treatment condition. The sufficient holding time for the precipitation of the β'' phase was estimated to be 6 hours for the alloy aged at 100°C and 10 hours for the alloy aged at 180°C. The low Copper containing Al-Mg-Si alloy gives rise to the forming a finer distribution of β (Mg2Si) precipitates which increases the hardness of the alloy. In order to know more about the precipitation reactions, concern the peaks on the DSC curve transmission electron microscopy observation were made on samples annealed at temperatures (250°C, 290°C and 400°C) just above the corresponding peaks of the three phases β'', β' and β respectively.
The results of studies of W-Ni-Co-Fe experimental alloy, with chemical composition assuring a possibility of producing Ni-based supersaturated solid solution are presented. The alloy was prepared from tungsten, nickel, cobalt and iron powders which were first mixed then melted in a ceramic crucible where they slowly solidified in hydrogen atmosphere. Next specimens were cut from the casting and heated at a temperature 950o C. After solution treatment the specimens were water quenched and then aged for 20 h at a temperature 300o C. The specimens were subjected to microhardness measurements and structure investigations. The latter included both conventional metallography and SEM observations. Moreover, for some specimens X-ray diffractometry studies and TEM investigations were conducted. It was concluded that quenching lead to an increase of tungsten concentration in nickel matrix which was confirmed by Ni lattice parameter increase. Aging of supersaturated solid solution caused strengthening of the Ni-based matrix, which was proved by hardness measurements. The TEM observation did not yield explicit proofs that the precipitation process could be responsible for strengthening of the alloy.
Temperature and precipitation conditions in the Kaffiøyra region in the summer season (21 July-31 August) for the period from 1975-2014 are described based on data collected during 22 expeditions, in which meteorological measurements were carried out, and complete data series combining both original and reconstructed data. The latter ones were obtained using data from the Ny Ålesund meteorological station, which are strongly correlated with data from the Kaffiøyra region. Seasonal statistics presented for temperature and precipitation based on these two sets of data reveal only slight changes. Summer temperatures in the Kaffiøyra region in the studied period (1975-2014) showed statistically significant strong upward trends, while precipitation totals revealed a downward trend, but not statistically significant. In the studied area, based on 40-years of data, it was demonstrated that the near-surface lapse rates of summer air temperature are slightly lower in glaciated (0.58°C/100 m) than in non-glaciated areas (0.67°C/100 m). Anticyclonic/cyclonic circulation types significantly increase/decrease air temperature on the Waldemar Glacier, while their impact on precipitation is markedly smaller. In summer, close correlations were observed between air temperature and such glacier characteristics as the mass balance and the location of the equilibrium line, while precipitation does not have a great influence on them.
One type of spheroidal cast iron, with additions of 0.51% Cu and 0.72% Ni, was subjected to precipitation hardening. Assuming that the greatest increase in hardness after the shortest time of ageing is facilitated by chemical homogenisation and fragmentation of cast iron grain matrix, precipitation hardening after pre-normalisation was executed. Hardness (HB), microhardness (HV), qualitative and quantitative metalographic (LM, SEM) and X-ray structural (XRD) tests were performed. The acquired result of 13.2% increase in hardness after ca. 5-hour ageing of pre-normalised cast iron confirmed the assumption.
This work presents the results of a study whose aim was to determine the influence of algal blooms on precipitation of heavy metals. The scope of the study covered culture of a mixed population made up of Scenedesmus and Pseudokirchneriella algae in experimental conditions and initiating a metal biosorption process with the use of culture biomass by administering ions of Zn(II) and Ni(II). The process was controlled by assessing the level of biosorption of metals entered at a one-off basis in the form of Zn(II) and Ni(II) salts or in the form of mixture of both ions, in comparison to the control sample, at different exposure times (2 hours and 24 hours). The presence of metals was determined both in the biomass and in the culture medium. The presented results of the study confirm the effectiveness of Chlorophyta in the process of zinc and nickel biosorption. A phenomenon of competitiveness between the metals was observed when they were administered at the same time.
An ecoefficient, economical and sustainable valorization process for the synthesis of Co3O4 from waste lithium-ion battery (LIB) by leaching-solvent extract-scrubbing-precipitation stripping route has been developed. Through an optimization, the waste LIB cathode was leached using 2000 mole/m3 of H2SO4 and 5 Vol. % of the H2O2 at a pulp density of 100 kg/m3 under leaching time 60 minutes and temperature 75 °C. From the separated leach liquor, cobalt was purified by saponified Cyanex 272. From cobalt, loaded Cyanex 272 impurities were scrubbed and the CoC2O4·2H2O was recovered through precipitation stripping. Finally, the precipitate was calcined to synthesize Co3O4, which is a precursor for LIB cathode materials manufacturing. From TGA-DTA, followed by XRD analysis it was confirmed that at 200 °C the CoC2O4·2H2O can be converted to anhydrous CoC2O4 and at 350 °C the anhydrous can be converted to Co3O4 and at 1100 °C the Co3O4 can be converted to CoO. Through reported route waste LIB can back to LIB manufacturing process through a versatile and flexible industrial approach.
The climatic change on King George Island (KGI) in the South Shetland Islands, Antarctica, in the years of 1948–2011 are presented. In the reference period, a statistically significant increase in the air temperature (0.19 ° C/10 years, 1.2 ° C in the analysed period) occurred along with a decrease in atmospheric pressure (−0.36 hPa/10 years, 2.3 hPa). In winter time, the warming up is more than twice as large as in summer. This leads to decrease in the amplitude of the annual cycle of air temperature. On KGI, there is also a warming trend of daily maximum and daily minimum air temperature. The evidently faster increase in daily minimum results in a decrease of the diurnal temperature range. The largest changes of air pressure took place in the summertime (−0.58 hPa/10 years) and winter (−0.34 hPa/10 years). The Semiannual Oscillation pattern of air pressure was disturbed. Climate changes on KGI are correlated with changing surface temperatures of the ocean and the concentration of sea ice. The precipitation on KGI is characterised by substantial variability year to year. In the analysed period, no statistically significant trend in atmospheric precipitation can be observed. The climate change on KGI results in substantial and rapid changes in the environment, which poses a great threat to the local ecosystem.
It is generally accepted that ice cores archive amount-weighted water stable isotope signals. In order to achieve an improved understanding of the nature of water stable isotope signals stored in ice cores annual δ18O and δ2H averages (i.e. amount-weighted) were calculated for two Antarctic meteorological stations, Vernadsky and Hal-ley Bay, using monthly precipitation amount and monthly net accumulation as weights, respectively. These were then compared with the annual mean δ18O δ2H and records of the nearest available ice cores. In addition, at the stations, both arithmetic means (i.e. time-weighted) and amount-weighted (precipitation amount and net accumulation used as weights) annual air temperature averages were calculated and then compared to amount weighted annual mean δ18O and δ2H using correlation- and regression analyses. The main hypothesis was that amount weighted annual mean water isotope and temperature records from the stations would be able to replicate the annual water isotope signal stored in ice cores to a higher degree. Results showed that (i) amount weighting is incapable of ameliorating the signal replication between the stations and the ice cores, while arithmetic means gave the stronger linear relationships; (ii) post depositional processes may have a more determining effect on the isotopic composition of the firn than expected; and (iii) mean annual air temperature provided the closest match to ice core derived annual water isotope records. This latter conveys a similar message to that of recent findings, in as much as ambient temperature, via equilibrium isotope fractionation, is imprinted into the uppermost snow layer by vapor exchange even between precipitation events. Together, these observations imply that ice core stable water isotope records can be a more continuous archive of near-surface temperature changes than hitherto believed.