Free Ion Form Research Articles

Extreme-ultraviolet studies with laser-produced plasmas

A new multilaser multichannel spectrometer system has been developed that allows a wide range of investigations of the interaction of extreme-ultraviolet (EUV) photons with matter in the form of free atoms or ions, e.g., in gases or plasmas or bound as in solids. The EUV photons are generated by a laser-produced plasma. Applications to the study of photoabsorption by thin foils, gases, and ground- and excited-state atoms and ions are described. The design and performance of a collimated, quasi-monochromatic, intense source of EUV radiation based on the combination of a laser-produced plasma with a EUV multilayer mirror is also reported.

Water-soluble organic matter in forest soils

Soil culture experiments were conducted to examine the effects of water-soluble organic matter (WSOM), isolated from the A h horizon of a forest soil on cation uptake by seedlings of Agrostis capillaris and Silene dioica. In contrast to the large effects on soil equilibria, cation uptake was only slightly affected by WSOM. Solubilized Al, Fe, Cu and Pb, were not found in higher amounts neither in the root nor in the shoot of the test species. Significant effects were only found for Cd, Mg, Mn and Zn, where uptake was either enhanced or decreased by WSOM. An experiment with several standard low molecular weight organic acids affirmed the results obtained with WSOM and supported the hypothesis that cations are taken up predominantly in the free ionic form and not as organic complexes [...]

IR and Raman spectra of the new Ba 1.5Sr 0.5CuO 3+δ(CO 2) y carbocuprate

Raman scattering and infrared absorption spectra on optical phonons in semiconducting ceramic Ba 1.5Sr 0.5CuO 3+δ(CO 2) y are reported. Characteristic IR and Raman internal vibrational bands of the CO 2- 3 group confirm the incorporation of carbon in the form of the carbonate CO 2- 3 ion in these new perovskite compounds. Raman spectra give evidence that disorder is present in the carbon containing layer. The carbonate group is found to be deformed with respect to free ion form. A number of lines belonging to impurity phases are identified in the spectra.

Accumulated forms of thallium and cadmium inLemna minor. I. Distribution in aqueous soluble and insoluble fractions

The distribution and chemical forms of thallium (Tl) and cadmium (Cd) in Lemna minor have been investigated using extractants of different polarity, enzyme digestion and ultrafiltration and chromatographic methods. Over 80% of Tl and 60% of Cd taken up by the plant was found in aqueous soluble forms. Water was more efficient than ethanol in extracting both elements; about 30% of bound Cd was released by dilute HCI treatment and Cd was mainly bound to pectins and proteins in the cell wall fractions but only a small proportion of Tl was associated with these components. In the aqueous soluble extracts a sizeable proportion of Cd was complexed with soluble moieties, including proteins; whereas Tl seems to be mainly present in the free ionic form.

Acute Copper and Cupric Ion Toxicity in an Estuarine Microbial Community

Copper was acutely toxic to the estuarine microbial community of Middle Marshes, N.C. Under ambient water quality conditions, 10 mug of added total copper [Cu(II)] liter reduced the CFU bacterial abundance by up to 60% and inhibited the amino acid turnover rate (AATR) by as much as 30%. Copper toxicity, however, was a quantitative function of free cupric ion (Cu) activity that was not directly related to Cu(II) or ligand-bound copper. By using a nitrilotriacetic acid-cupric ion buffer to control pCu (-log Cu activity), it was found that an in situ pCu of 10.1 was bactericidal, reducing the CFU by 60%, but inhibited the AATR by only about 10%. A bacterial bioassay that was used to estimate the pCu in Cu(II)-treated Middle Marshes samples indicated that less than 0.5% of added Cu(II) was in the free cupric ion form. CFU was a more sensitive indicator of low-level copper stress than was AATR. When tested at different times, native microbial community responses to acute cupric ion stress were quantitatively quite similar even when there were large differences in bacterial abundances and in situ metabolic rates. Variations were observed in response to Cu(II) treatments at different times, but these were likely due to differences in water quality, which would quantitatively influence the distribution of copper complexes that were present. Asymptotic response curves suggest that some degree of copper resistance exists in this community. At a pCu of 8, more than 2 orders of magnitude above the minimum inhibitory level, the CFU was still 5 to 10% and the AATR was about 3% of the control values.

The effects of soil organic matter levels on soil solution concentrations and extractabilities of manganese, zinc and copper

To determine the effect of soil organic matter on concentrations of metals in soil solution and their extractability from soil, solutions containing varying concentrations of Mn, Zn and Cu salts were added to five samples of a sandy loam soil with organic matter levels ranging from 0.8 to 2.4% C. Concentrations of the metals and their ions in solutions displaced from the samples after 3 weeks of incubation were determined. Extractabilities of the metals by both single extractants (EDTA and acetic acid) and by a sequential extraction scheme (calcium chloride, hydrogen peroxide, acetic acid and aqua regia), and release of the metals into solution as a function of pH were also studied. The total concentration of Mn, Zn and Cu in displaced solutions were almost independent of the organic matter status of the samples, but cupric ion concentrations were smallest in solutions displaced from samples with high organic matter content. The percentage of the total amount of each metal present in free ionic form in solution was 45–90, 15–65 and < 20% for Mn, Zn and Cu , respectively. When EDTA and acetic acid were used as single extractants, extractability showed no discernible trend across the range of organic matter in the samples with no metal added. Acetic acid did, however, extract less of the Zn and Cu that was added to samples with more organic matter. There was no effect of organic matter status on the extractability of Mn. In the sequential extractions, smaller proportions of either native or added Cu were solubilised by calcium chloride from the samples with more organic matter than from others; also acetic acid extracted less of the added Zn and very much less added or native Cu from samples higher in organic matter. Conversely, hydrogen peroxide extracted higher concentrations of metals from samples with more organic matter than from others. In the study of effects of pH, smaller concentrations of Zn and Cu were extracted at every pH from the sample with the most organic matter than from the sample lowest in organic matter.

Changes of intracellular calcium homeostasis in brain cortical structures during anoxia in vivo and in vitro

This work characterizes the anoxia-evoked changes in the content of bound calcium (Ca b) in brain cortex membraneous structures, studied in vivo, on living brain cortex preparation and in vitro, on subcellular fractions (synaptosomes, microsomes and mitochondria) in anoxic conditions. The chlorotetracycline (CTC) fluorescent chelate probe was used to monitor changes of Ca b content in hydrophobic domains of intracellular membranes. In in vivo experiments the bioelectric activity of single neurons was recorded simultaneously with measurements of Ca-CTC fluorescence. In vitro experiments were supplemented with determinations of synaptosomal 45Ca-uptake. It was found that the response of cortical neurons to anoxia is manifested in a decrease of a portion of Ca 2+ bound with membrane hydrophobic domains. These in vivo changes preceded the noticeable disturbances of neuronal electric activity. An anoxia-evoked drop in Cab was also clearly demonstrated in vitro, irrespective of K + (for synaptosomes) or Na + (for mitochondria) concentrations in incubation media, although the additional effect of Ca b displacement was noted when Na +/K + concentrations were modified in order to simulate their changes occurring in anoxic conditions. It was found that the membranes of different neuronal compartments are not uniformly vulnerable to anoxia in vitro as the anoxic decrease in Ca b content occurred in synaptosomes and microsomes much sooner than in mitochondria. Therefore, in vivo and in vitro experiments visualized high sensitivity of Ca 2+-binding mechanisms in different neuronal membranes to anoxia. The anoxia-evoked displacement of a portion of Ca b to the free ionic form may trigger a compelx intracellular response determining anoxic reactions and post-anoxic recovery.

Role of divalent cations in plasma opsonin-dependent and-independent erythrophagocytosis by hemocytes of the Asian clam, Corbicula fluminea

The in vitro phagocytosis-promoting properties of hemolymph from the freshwater clam, Corbicula fluminea, are described. Hemocytes were capable of phagocytosing aldehyde-fixed erythrocytes (RBCs) of seven vertebrate species with equal facility, but only in the presence of homologous clam plasma. The plasma factors mediating erythrophagocytosis were heat sensitive. Pretreatment (opsonizing) of target RBCs with plasma also resulted in enhancement of hemocyte particle uptake in the absence of plasma. Opsonin-dependent phagocytosis required the presence of divalent cations, especially calcium, although not in free ionic form. Evidence suggests that the plasma opsonin may normally exist as a divalent cation-macromolecular complex since opsonizing activity was retained after dialysis against Tris-buffered saline (TBS), but was lost following TBS/EDTA or TBS/EGTA dialysis. We also have identified an opsonin-independent phagocytosis mechanism in which Corbicula hemocytes are able to ingest nonopsonized RBCs in the absence of homologous plasma. Extracellular calcium or magnesium in the incubation medium is needed for particle uptake, although the direct binding of free ions to the target RBC surface does not appear to be mediating enhanced phagocytosis. From the present data, it is concluded that hemocyte recognition of aldehyde-fixed RBCs can be accomplished by either of two mechanisms: (1) by the coating of cells with plasma factors capable of triggering the phagocytic process (opsonization) or (2) by a plasma opsonin-independent mechanism in which extracellular divalent cations (e.g., Ca 2+ or Mg 2+) in the incubation buffer stimulate uptake of nonopsonized RBCs. The factors regulating in vitro erythrophagocytosis by clam hemocytes are considered to be analogous to those involved in nonimmune opsonin-dependent and -independent phagocytosis in mammalian macrophages.

Trace Metal Speciation in a Soil Profile Irrigated with Waste Waters

A chemical equilibrium computer model: GEOCHEM, was used to predict the trace metal behavior in a soil profile if subjected to a long-term irrigation with waste waters. Various categories of interactions such as acid-base equilibria, soluble complex formation of metals with organic and inorganic ligands, dissolution-precipitation reactions and ion-exchange reactions were included in simulation. The metal-soluble organic interactions were accounted for by a mixture model. The computations included a 10 metal - 15 ligand system with 262 soluble complex species and 21 possible solid phases. The results predicted that a major fraction of alkali elements in solution tend to be in free ionic forms, whereas, major fractions of the alkaline earths were predicted to be present in adsorbed and/or precipitated forms. In marked contrast, significant soluble fractions of transition series metals were predicted to be in adsorbed and/or complexed forms. The degree of attenuation of these transition series elements moving through the soil profile seems to be governed mainly by the degree of adsorption on soil surfaces and the tendency of these elements to form soluble organic complexes. The predicted mobilities of these elements in this soil profile was Cu &amp;gt; Ni &amp;gt; Zn &amp;gt; Cd. Application of this equilibrium model appears to provide a first approximation approach to simulate the trace element behavior in soil profiles.

Reanalysis of polarised neutron data on NiRu using projection operator formalism

Projection operator formalism has been applied to analyse magnetic structure amplitudes in Ni1−xRux (x=0·027, 0·033 and 0·046) alloys. This method is suitable for metals and alloys as it does not assume any free ion form factor. A new prescription has been discussed for the local site moment and diffuse moment in this frame work. The results of the present analysis are compared with those obtained using form factor analysis.

Chemical composition of aqueous extracts of fly ash: Ionic speciation as a controlling factor

Abstract Concentrations of Na, K, Ca, Mg, SO4, and Si in eight successive extracts of a fly ash sample were determined. Calculation of elemental speciation in solution phase using the chemical equilibrium computer program: GEOCHEM indicated that Na and K were mainly in the free ionic forms whereas, concentrations of Ca2+ and Mg2+ constituted 58–92% of the total analytical concentrations. Concentrations of Ca and Mg ion pairs with OH‐ and SO2‐ 4 ions ranged from 8–42% of total concentrations. Computed saturation indices suggested that the precipitation‐dissolution reactions of ettringite, brucite, sepiolite, laumontite, and phillipsite may be controlling various ion activities in the extracts.

The use of liquid chromatography in the study of cadmium speciation in soil solutions from polluted soils

SummaryChromatographic methods were used in an attempt to identify the various species of cadmium in soil solution. Exclusion and reverse‐phase chromatography using HPLC showed that cadmium existed in the form of low‐molecular weight, highly polar species. Ion‐exchange chromatography was used to divide soil solution cadmium into cationic, anionic and neutral species. Cadmium was found to be mainly in the form of inorganic cationic species, including the free ionic form, Cd2+, and some as neutral species, possibly organic as well as inorganic, especially in soils of higher pH. Anionic species were relatively unimportant. These results showed general agreement with those of other authors using computer models to predict cadmium speciation in soil solution.

Silver staining of macromolecules separated by electrophoresis

The use of silver, either in the free ionic form or as a diamine complex, has become important for staining proteins, nucleic acids and lipopolyaccharides separated by acrylamide gel electrophoresis. A number of applications and methodologies have been developed for this staining procedure over the last four years.

Predicted Solution Phase Forms of Heavy Metals in Sewage Sludge‐Treated Soils

AbstractChemical speciation of selected elements in the soil solution of sewage sludge‐treated soils was studied with aid of the computer program, GEOCHEM. Soil solutions were obtained by the saturation extract method from reconstructed soil profiles where anaerobically digested sewage was incorporated into the top 15 cm of the soil and the soils were leached for 25 months. Total concentrations of Cd, Cu, Ni, and Zn in the soil solutions were elevated by the sewage sludge addition, but in most cases were within ranges found in a survey of soils untreated with sludge. Concentrations of the metals were so low that their contribution to metal movement over the duration of the study was negligible. Concentration changes in solution metals across the sludge‐soil interface in most columns was dramatic. For Cd, Ni, and Zn between 50 and 60, 60 and 70 and 60 and 70%, respectively, of the total metal in solution was found to be in the free ionic form. Copper was almost exclusively in organically compelxed forms in sludge‐soil layers, and below these layers the form of Cu shifted to the free ionic form as the pH decreased. Activities of the metals indicated undersaturation with respect to established minerals in soils.

Effects of long term infusion of sodium nitroprusside on iron and thiocyanate in rabbits

The infusion of 0.75 mg/kg/h sodium nitroprusside (SNP) for 40 h in rabbits leads to a significant rise of the plasma thiocyanate concentration, irrespective of whether SNP was infused alone or in combination with sodium thiosulphate (ST). The iron concentration in the plasma is slightly increased, but the iron-binding capacity is not exceeded. The infusion of SNP in rabbits resulted in an elevation of the non-Hb iron in the liver in every case. About 60% of the infused SNP iron is found in the liver, whilst after FeSO4 infusion only about 30% of the administered iron is deposited in the liver. The higher iron content of the liver after SNP-infusion shows that SNP-iron is not taken up in free ionic form in this organ. The question of whether and to what extent the complex is broken down before being taken up remains unanswered.

Ionisation von Triphenylmethylbromid in Nitromethan

Ionisation of Triphenylmethylbromide in NitromethaneDissolving triphenylmethylbromide in nitromethane leads to the formation of HBr which complicates conductivity and spectroscopic measurements of carbenium ion absorption. As a result of addition of bromide ions (as tetraethylammonium bromide = Et4NBr) the triphenylmethylabsorption totally disappeares. It can be concluded that Ph3CBr in nitromethane is partially present in form of free (solvated) ions. The carbenium ion concentration has been determined as a function of gross concentration and temperature.

Determination of Total and Ionic Calcium in Apple Leaf and Fruit Tissues1

Abstract Apple (Malus domestica Borkh.) leaf, peel, and flesh tissues were sequentially fractionated using hot water, sodium nitrate, acetic acid and hydrochloric acid to extract Ca in various forms. Water soluble and sodium nitrate exchangeable Ca, which were considered to be the physiologically active forms, composed 53%, 78 %, and 73 % of the total Ca present in apple leaf, peel, and flesh tissues, respectively. Ionic Ca was determined in each of the fractions using an ion-selective electrode. Eleven to 42% of the total Ca concentration in each of the fractions was found to be in the free ionic form. Bound and exchangeable Ca in each of the fractions was also measured by an ion exchange resin in a batch method, and exchangeable Ca was 19 to 87% of the total.

Analysis of form factors observed with polarized neutrons; comparison with band structure calculations

For the analysis of observed magnetic neutron form factors of transition metals and alloys different methods are being used. These methods are i) fitting of theoretical free-ion form factors to the experimental data, ii) Fourier analysis, as introduced by Moon, which does not require any a priori knowledge of the form factor but, instead, extracts its spin and orbital parts from the data, and iii) a modified version of ii) that properly takes into account the full symmetry of the crystal lattice. Spherical spin form factors appearing in i), ii) and iii) are compared with those based upon band structure calculations for Fe and Ni. It is found that only the results of iii) are in agreement with band theory. Since neither band theory nor method iii) leads to the existence of a uniform negative spin density this concept should be abandoned.

The effects of organic and inorganic lead and mercury on neurotransmitter high-affinity transport and release mechanisms

The effects of two heavy metals upon the high-affinity transport system of certain putative neurotransmitters have been studied in adult mouse brain homogenates. Carbon-linked and free ionic forms of mercury and lead were compared. Tri- n-butyl lead acetate at concentrations as low as 10 −6, m severely inhibited the sodium-dependent, energy-requiring uptake of a variety of putative neurotransmitters. Dopamine uptake was more affected than other compounds. Ionic lead (as lead acetate) was several orders of magnitude less toxic than the covalently bound lead compound. Methylmercuric chloride and mercuric chloride had an intermediate inhibitory effect on the high-affinity transport system, significant impairment becoming apparent only at around 10 −5, m. Both metals stimulated the release of labeled compounds accumulated by high-affinity transport systems in brain homogenates. This stimulation was greater with tributyl lead acetate than with any other compound tested. The effect was independent of and additive to the stimulatory effect of the calcium ion on neurotransmitter release. Unlike calcium, heavy metals could effect release of transported compounds in the absence of depolarizing conditions. While calcium-mediated release requires over 0.3 m m Ca 2+ to be detected, tributyl lead acetate-mediated release of several putative transmitters was apparent at 5 × 10 −6, m and mercury compounds had major releasing effects at 5 × 10 −5, m. The uptake and release of dopamine was especially strongly affected by covalently bound lead whose effects could be detected at 10 −8, m.

Polarized Neutron Diffraction Study of a CuCr2Se4Single Crystal

The electronic state of CuCr 2 Se 4 is investigated by means of the polarized neutron diffraction technique. From the measured form factors of copper and chromium atoms, the magnetic moments are determined to be -0.07±0.02 (µ B /Cu) and 2.64±0.04 (µ B /Cr), respectively. Further, the uniform polarization existent throughout the crystal is estimated to be -0.20±0.11 µ B per formula unit, using the total moment 5.01±0.01 (µ B /CuCr 2 Se 4 ) obtained from the magnetization measurement. This result which differs from those reported by other authors with neutron diffraction, shows that neither of the ionic configuration models of Cu + [Cr 3+ Cr 4+ ]Se 4 and Cu 2+ [Cr 3+ 2 ]Se 4 gives a satisfactory explanation of CuCr 2 Se 4 , although the former is closer to the experimental data. The form factor of the chromium atom agrees well with the calculated free ion form factor for Cr + , but not for Cr 3+ , and this fact indicates that the unpaired electron density on the chromium atom is more spread than that for fr...