Experimental Study on the Chloride Ion Concentration of Cement Pastes Prepared with Limestone Powder

To investigate the impact of limestone powder on the chloride ion concentration coefficient of cement pastes,various techniques such as scanning electron microscopy(SEM),X-ray diffraction(XRD),thermogravimetric analysis(TGA),and mercury-porosimetry(MIP)were employed in this paper.The findings demonstrate that the creation of Friedel's salt is inversely associated with the addition of limestone powder,that is,Friedel's salt production is lessened by adding more limestone powder,however,the coefficient of chloride ion concentration initially decreased and then increased again,as does the porosity,and most likely the pore size as well.The specific surface area of limestone powder has increased,and the content of Friedel’s salt increased first and then decreased.However,the shifting trend of Friedel's salt and chloride ion concentration coefficient is in direct opposition,and the pore structure was therefore significantly enhanced.The results of this study offer robust theoretical backing for the inclusion of limestone powder in concrete and provide a positive assessment of its potential applications.

Effect of Sodium Ion Concentration on Hydrogen Production from Sucrose by Anaerobic Hydrogen-producing Granular Sludge

This work evaluated the effects of sodium ion concentration, ranging from 0 to 16000mg·L^-1（Na^＋）, on the conversion of sucrose to hydrogen by a high-activity anaerobic hydrogen-producing granular sludge. At the optimum sodium ion concentration [1000-2000mg·L^-1（Na^＋）] for hydrogen production at 37℃, the maximum sucrose degradation rate, the specific hydrogen production yield and the specific hydrogen production rate were 393.6-413.1mg·L^-1.h^-1, 28.04-28.97ml·g^-1, 7.52-7.83ml·g^-1.h^-1, respectively. The specific production yields of propionate, butyrate and valerate decreased with increasing sodium ion concentration, whereas the specific acetate production yield increased, meanwhile the specific production yields of ethanol and caproate were less than 55.3 and 12.6mg·g^-1, respectively. The hybrid fermentation composition gradually developed from acetate, propionate and butyrate to acetate with the increase in sodium ion concentration.

Influence of chloride ion concentration on immersion corrosion behaviour of plasma sprayed alumina coatings on AZ31B magnesium alloy

Corrosion attack of aluminium and magnesium based alloys is a major issue worldwide.The corrosion degradation of an uncoated and atmospheric plasma sprayed alumina(APS)coatings on AZ31B magnesium alloy was investigated using immersion corrosion test in NaCl solutions of different chloride ion concentrations viz.,0.01 M,0.2 M,0.6 M and 1 M.The corroded surface was characterized by an optical microscope and X-ray diffraction.The results showed that the corrosion deterioration of uncoated and coated samples were significantly influenced by chloride ion concentration.The uncoated magnesium and alumina coatings were found to offer a superior corrosion resistance in lower chloride ion concentration NaCl solutions(0.01 M and 0.2 M NaCl).On the other hand the coatings and Mg alloy substrate were found to be highly susceptible to localized damage,and could not provide an effective corrosion protection in solutions containing higher chloride concentrations(0.6 M and 1 M).It was found that the corrosion resistance of the ceramic coatings and base metal gets deteriorated with the increase in the chloride concentrations.

Effects of Trajectory Wind Direction on Ion Concentration of PM_(10)

Objective To study the characterization apportionment of main ion concentrations of PM10 under the influence of trajectory wind direction in London. Methods PM10 samples from 1 May 1995 to 30 October 1995 of Oxford Street of Central London were collected, the metals and anions of which were measured using atomic absorption spectrometry （AAS） and ion chromatography （IC）. Composite trajectories representative of the air mass arriving in London at the same period were calculated based on basic routine back trajectories from the British Atmospheric Data Centre （BADC）. Results Concentration apportionments of main ions were similar when the trajectory was plotted back at 6 h, 12 h, and 24 h, some were obviously different. Mg, Ba, Pb, and Cu had similar peak apportionments at the area 180°-320°, but Zn and Ni at the area of 90°-270°, NO3^- and SO4^2- at the area of 100°-220°. Cl^- concentration peak apportionment was at the area of 220°-300°, which showed that Cl^- mainly came from the North Sea. Conclusion Trajectory wind direction has important effect on ion concentration apportionment of PM10 in London. The ions have similar concentration peak apportionments or their correlation coefficients are statistically significant.

Er^(3+) ion concentration effect on transient and steady-state behavior in Er^(3+):YAG crystal

The effect of Er3＋ ion concentration on transient and steady-state behavior in 45-nm Er3＋ ：YAG crystal is investigated. It is shown that by changing the signal field, the coherent field and the concentration of Er3＋ ions in the crystal, the absorption, dispersion, and group index of the weak probe field can be adjusted. Also, it is found that the probe absorption occurs in the presence of population inversion and probe amplification is obtained in the absence of population inversion.

A new approach to endocochlear potential and potassium ion concentration measures in mini pig models

Mini pig models are large mammals and their ears are more similar with human beings in structure and development than other animals.However,the study on porcine ears is still in the initial stage and there is no description of an ideal operation approach to endocochlear potential and potassium ion concentration measurements.In this article,we describe a pre-auricular surgical approach to access the middle and inner ear for endocochlear potential and potassium ion concentration measures in mini pig models.Ten one-week old normal mini pigs were used in the study.The bulla of the temporal bone was accessed via a pre-auricular approach for endocochlear potential and potassium ion concentration measurements.The condition of the animals during the first post—experiment 24 h was observed.One animal died during surgery.The preauricular approach improved protection and preservation of relevant nervous and vascular elements including the facial nerve and carotid artery.So,the pre-auricular approach can be used for endocochlear potential and potassium ion concentration measurements with improved nerve and artery preservation mini pigs.

Combined effects of temperature and copper ion concentration on the superoxide dismutase activity in Crassostrea ariakensis

Superoxide dismutase（SOD） is a crucial antioxidant enzyme playing the first defense line in antioxidant pathways against reactive oxygen species in various organisms including marine invertebrates. There exist mainly two specific forms, Cu/Zn-SOD（SOD1） and Mn-SOD（SOD2）, in eukaryotes. SODs are known to be concurrently modulated by a variety of environmental stressors. By using central composite experimental design and response surface method, the joint effects of water temperature（18–34°C） and copper ion concentration（0.1–1.5 mg/L） on the total SOD activity in the digestive gland of Crassostrea ariakensis were studied. The results showed that the linear effect of temperature was highly significant（P〈0.01）, the quadratic effect of temperature was significant（P〈0.05）; the linear effect of copper ion concentration was not significant（P〉0.05）, while the quadratic effect of copper ion concentration was highly significant（P〈0.01）; the interactive effect of temperature and copper ion concentration was not significant（P〉0.05）; the effect of temperature was greater than that of copper ion concentration. The model equation of digestive gland SOD enzyme activity towards the two factors of interest was established, with R2 and predictive R2 as high as 0.961 6 and 0.820 7, respectively, suggesting that the goodness-offit to experimental data be very satisfactory, and could be applied to prediction of digestive gland SOD activity in C. ariakensis under the conditions of the experiment. Our results would be conducive to addressing the health of aquatic animals and/or to detecting environmental problems by taking SOD as a potential bioindicator.

Comparison of Quartz filter and PTFE filter in monitoring anion ion concentration of PM10

PM10 samples of 62 Quartz filters and 75 PTFE filters from 28 Jul. 1999 to 10 Jan. 2000 in London were collected and analyzed. The difference between Quartz filter and PTFE filter in monitoring PM10 and anion ion concentration has been studied. The mean PM10, SO42- concentrations of Quartz filters were higher than those of PTFT filters, which had statistically significant （P〈0.05）. The mean PM 10 concentration of Quartz filter was almost 1.5 times of that of PTFE filter. However, there were no statistically significant among CI, NO3-, PO43 comparison of the two kinds filters （P〉0.05）. We should be careful when selecting filter to do research about PM10 and anion ion concentration.

Combined effects of water temperature and copper ion concentration on catalase activity in Crassostrea ariakensis

A central composite experimental design and response surface method were used to investigate the combined effects of water temperature(18–34℃) and copper ion concentration(0.1–1.5 mg/L) on the catalase(CAT) activity in the digestive gland of C rassostrea ariakensis. The results showed that the linear effects of temperature were significant(P <0.01), the quadratic effects of temperature were significant( P <0.05), the linear effects of copper ion concentration were not significant(P >0.05), and the quadratic effects of copper ion concentration were significant(P <0.05). Additionally, the synergistic effects of temperature and copper ion concentration were not significant(P >0.05), and the effect of temperature was greater than that of copper ion concentration. A model equation of CAT enzyme activity in the digestive gland of C. ariakensis toward the two factors of interest was established, with R 2, Adj. R 2 and Pred. R 2 values as high as 0.943 7, 0.887 3 and 0.838 5, respectively. These findings suggested that the goodness of fit to experimental data and predictive capability of the model were satisfactory, and could be practically applied for prediction under the conditions of the study. Overall, the results suggest that the simultaneous variation of temperature and copper ion concentration alters the activity of the antioxidant enzyme CAT by modulating active oxygen species metabolism, which may be utilized as a biomarker to detect the effects of copper pollution.

Effect of Sodium Ion Concentration on Hydrogen Production from Sucrose by Anaerobic Hydrogen-producing Granular Sludge

This work evaluated the effects of sodium ion concentration, ranging from 0 to 16000mg·L-1(Na+), on the conversion of sucrose to hydrogen by a high-activity anaerobic hydrogen-producing granular sludge. At the opti- mum sodium ion concentration [1000—2000mg·L-1(Na+)] for hydrogen production at 37℃, the maximum sucrose degradation rate, the specific hydrogen production yield and the specific hydrogen production rate were 393.6— 413.1mg·L-1·h-1, 28.04—28.97ml·g-1, 7.52—7.83ml·g-1·h-1, respectively. The specific production yields of propionate, butyrate and valerate decreased with increasing sodium ion concentration, whereas the specific acetate production yield increased, meanwhile the specific production yields of ethanol and caproate were less than 55.3 and 12.6mg·g-1, respectively. The hybrid fermentation composition gradually developed from acetate, propionate and butyrate to acetate with the increase in sodium ion concentration.

The Combined Impact of Magnetic Field and Chloride Ion Concentration on Corrosion Behavior of Al-Mg Alloys

The impact of magnetic field on the corrosion behavior of Al-Mg-xR_(E)/Fe alloys in NaCl solutions with concentrations of 1.5wt%,3.5wt%,and 5.5wt%were studied by microstructure observation,immersion test,and electrochemical test.The combined impacts of magnetic field and chloride ion concentration on the corrosion behavior of Al-Mg alloys with various electrode potential phases were discussed.The results indicate that Al-3.0Mg-xR_(E)/Fe alloys corrode faster and have a higher pitting corrosion potential in the NaCl solution with a higher concentration.In addition,a magnetic field can lower the pitting sensitivity and corrosion rate of Al-3.0Mg and Al-3.0Mg-0.2R_(E)/Fe alloys in NaCl solution with different concentrations.However,at a higher concentration of NaCl solution,the magnetic field has a weaker inhibiting effect on corrosion rate and pitting sensitivity.In NaCl solutions with concentrations of 1.5wt%and 3.5wt%,the corrosion rate and pitting sensitivity of Al-3.0Mg-1.0R_(E)/Fe alloys can be reduced by a magnetic field.However,in NaCl solution with the concentration of 5.5wt%,the corrosion rate of the alloys is increased by a magnetic field.

Role of incoherent pumping and Er^(3+) ion concentration on subluminal and superluminal light propagation in Er^(3+)-doped YAG crystal

We study the absorption-dispersion process and group index of weak probe field in a four-level Er^3＋：YAG crystal.We find that the Er^3＋ion concentration and incoherent pumping field can influence the absorption-dispersion process and group index of weak probe field. Moreover, our results show that Er^3＋ion concentration plays a major role in lasing without inversion and absorption with inversion.

Impact of Hydrogen Ion Concentration on Amino Acids Composition of Macadamia Protein: Approached Using Cation-Exchange Chromatography

In the present context, the objective of this study was to synthesize and analyze the content of AA of macadamia protein and the impact of hydrogen ion concentration (pH) on AA composition. The determination of AA mainly by cation-exchange chromatography was also investigated. Reproducible and reliable techniques for quantification and identification of AA usually require derivatization. However, techniques such as AA analyzer are composed of cation-exchange chromatography and other components can sideline the derivatization with significant accuracy. The present analysis revealed a higher concentration of essential amino acids especially acidic AA, Glu and Asp and basic AA, Arg than other AA in macadamia protein. The study constitutes first report of use of bubble chart for evaluation of AA and explaination of AAS. The results may elaborate that the degradation of AA of macadamia protein for extraction of pH 11 is caused by the impact of pH. Moreover, the nutritional values of AA present in macadamia protein could change for the better by adjusting pH of extraction.

Corrosion behavior of micro-arc oxidation coating on AZ91D magnesium alloy in NaCl solutions with different concentrations

Ceramic oxide coatings were prepared on AZ91D magnesium alloys in alkaline silicate solution using micro-arc oxidation（MAO） technique.The corrosion behavior of MAO coating on AZ91D magnesium alloys in NaCl solutions with different concentrations（0.1%,0.5%,1.0%,3.5% and 5.0% in mass fraction） was evaluated by electrochemical measurements and immersion tests.The results showed that the corrosion rate of the MAO coated AZ91D increased with increasing chloride ion concentration.The main form of corrosion failure was localized corrosion for the MAO coated AZ91D immersed in higher concentration NaCl solutions（1.0%,3.5% and 5.0%）,while it was general corrosion in dilute NaCl solutions（0.1% and 0.5%）.Two different stages of the failure process of the MAO coated AZ91D could be identified：1） occurrence of the metastable pits and 2） growth of the pits.Different equivalent circuits were also proposed based on the results of electrochemical impedance spectroscopy（EIS） for the MAO coated AZ91D immersed in different concentrations of NaCl solutions for 120 h.

Factors influencing the concentration of negative air ions during the year in forests and urban green spaces of the Dapeng Peninsula in Shenzhen, China

Negative air ions(NAIs)benefit the mental and physical health of humans,but rapid urbanization can decrease the abundance of NAIs.Quantifying the spatial and seasonal distribution of NAIs and determining the factors that infl uence the concentration during urbanization is thus essential.In the present study of a typical developing urban district in southern China,negative air ion concentrations(NAICs)in 60 forests sites and 30 urban green spaces were quantifi ed on seven consecutive days in each of the four seasons.Large seasonal variations in NAIC were revealed in forests and urban green spaces with trough values in summer.NAIC progressively decreased from forests to urban green spaces and was infl uenced by local land morphology,vegetation characteristics,and climatic factors.The vast,heavily vegetated northeastern region was the richest area for NAIs,whereas the narrow central region(urbanized area)was the poorest,implying dramatic impacts of urbanization on the spatial distribution of NAIs.The relationship between air temperature and NAIC was better fi tted with a quadratic equation than a linear equation.Moreover,the NAIC was more sensitive to local morphology in urban green spaces than in urban forests,indicating the vulnerability of NAIs in urbanized areas.Therefore,the appropriate design of local urban morphology is critical.

Effect of Yb^(3+) concentration on the structures and upconversion luminescence properties of Y_2O_3:Er^(3+) ultrafine phosphors

Y2O3：Er^3＋ ultrafine phosphors with a varying Yb^3＋ ion concentration were prepared by a urea homogeneous precipitation method. The results of XRD show that all the samples are of a pure cubic structure and the average crystallite sizes can be calculated as 45, 34, and 28 nm for Y2O3：Er^3＋ ultrafine phosphors with Yb^3＋ ion concentrations of 0, 10%, and 20%, respectively. The lattice constant and cell volume of the ultrafine phosphors decrease with enhancing Yb^3＋ ion concentration. The upconversion luminescence spectra of all the samples were studied under 980 nm laser excitation. The strong green and red upconversion emission were observed, and attributed to the ^2H11/2→^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 →^4I15/2 transitions of Er^3＋, respectively. The intensity of red emission increases with increasing Yb^3＋ ion concentration. The effect of Yb^3＋ ion concentration on the structures and upconversion luminescence mechanism were discussed.

HYDROGEN ION CONCENTRATION IN RAIN WATER

Continuous measurements of pH precipitation falling from cumulus clouds in semi-arid region (Colorado,USA),and in wet temperate zone(Bologna,Italy)were made.In Colorado the pH was constant at 7.3 for a period of time,and later changed to 7.0 and remained constant at this value during the remainder of the storm.In Italy the pH fluctuated continuously between the approximate values of 5.7 and 6.4 during the storm.The changes in hydrogen ion concentration reflect the chemical composition of cloud condensation nuclei and of scavenged aerosol particles and gases presented in the region.

Characteristics of ion concentrations in snowpits in Longyearbyen,Svalbard,Arctic

Snowpits samples were collected from three glaciers in the Longyearbyen region, Svalbard during March to May, 1996. Among major chemical species (Na +, K +, Ca 2+ , Mg 2+ , Cl -, NO - 3 and SO 2- 4), Cl - and Na +, which come mainly from sea salt aerosol, are the dominant soluble impurities in snowpits. In dirty layers of snowpits (representing autumn), the crustal cation Ca 2+ has the highest concentration among all species. Thus, snowpits have been dated by high values of Ca 2+ concentrations and less negative δ 18 O, which represent autumn and summer layers respectively. Seasonal variations in concentrations of sea salt ions ( Na +, Mg 2+ and Cl -), SO 2- 4 and NO - 3 have been identified. Results indicate that concentrations of these ions show high value in spring and summer. The spring maximum value likely results from long range transport of marine aerosol from north Atlantic storms( Na +, Mg 2+ and Cl -) and mid latitude anthropogenic pollution (SO 2- 4 and NO - 3 ). In summer, high concentrations of the sea salt species are attributed to local marine aerosol. The summer SO 2- 4 maximum likely reflects a combination of local marine aerosol, high scavenging ratios, and oxidation of marine biogenic emissions. In comparison, NO - 3 maximum may reflect lightening in the atmosphere and high scavenging ratios. In general, the major ion concentrations in snowpits in Svalbard is high in comparison with those found in snowpits from other remote regions, such as Greenland, Antarctic and Qinghai Tibetan Plateau, especially for sea salt species.

Optimization of two-factor(pH and ion concentration)simultaneous selection in HPLC using a statistical method

A computer-assisted method is presented for simultaneous optimization of pH and ion con- centration selection for the optimal separation in reversed-phase HPLC.The method is based on a polynomial estimation from nine preliminary experiments according to two-factor rectangular design. This is followed by a two-dimension computer scanning technique.Resolution is used as the selection criterion.Good agreement was obtained between predicted data and experimental results.

ELECTROCHEMICAL NOISE ANALYSIS OF THE INFLUENCE OF THE Zn^(2+)IONS CONCENTRATION ON ZINC ELECTROPLATING

The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.