Free sulfate

Kolthoff et al. [42] showed that the thermal decomposition of peroxydisulfate ion yielded two free sulfate radicals according to the following reaction ... 

In some cases, due to the highly polar character of the sulfate radicals, peroxydisulfate initiators can provide slow polymerization rates with some apolar monomers since the polar sulfate radicals cannot easily penetrate into the swollen micelle structures containing apolar monomers. The use of mercaptans together with the peroxydisulfate type initiators is another method to obtain higher polymerization rates [43]. The mercaptyl radicals are more apolar relative to the free sulfate radicals and can easily interact with the apolar monomers to provide higher polymerization rates. 

Hydrogen sulfide is excreted primarily as sulfate (free sulfate or thiosulfate) in the urine. It is also excreted unchanged in exhaled air and in feces and flatus. 

The reaction of a dicobalt complex bridged by a peroxo ligand with the sulfite ion has been reported. In this reaction, a dicobalt complex containing a bridging sulfato ligand is formed, along with free sulfate (196). 

Amniotic fluid contains estriol in a variety of forms notably free, sulfate, and glucuronide. Therefore the determination is for total estriol content. After extraction, the procedure is the same as just described for the urinary estriol. 

Ionization isomers differ in the anion that is bonded to the metal ion. An example is the pair [Co(NH3)5Br]S04, a violet compound that has a Co-Br bond and a free sulfate anion, and [Co(NH3)5S04]Br, a red compound that has a Co-sulfate bond and a free bromide ion. Ionization isomers get their name because they yield different ions in solution. 

Seston Deposition. Sulfur is a minor but essential nutrient for algal production, accounting for 0.15-1.96% of dry weight (35). Sulfur is present as proteins, sulfolipids, ester sulfates, and free sulfate (18.19.36-38) that occur in varying proportions depending upon species and environmental conditions. 

It is difficult to say from the 834S record of sedimentary sulfur-bearing minerals when the oceans accumulated significant oxidized sulfur. It is likely that the activity of photosynthetic green and purple sulfur-oxidizing bacteria produced the first free sulfate in the environment by reactions like... 

Thus, the appearance of free sulfate does not require the advent of free oxygen in the Archean environment. Certainly sufficient free sulfate had appeared in the hydrosphere prior to development of the pathway of dissimilatory sulfate reduction. Schidlowski (1979) argues that the small fractionations observed between sulfide and sulfate 834s values of pre-2.7 billion year rocks (Figure 10.11) are consistent with the hypothesis that the oxidation of sulfide to sulfate by photosynthetic bacteria preceded the bacterial pathway of dissimilatory sulfate reduction and may have been responsible for early free dissolved sulfate concentrations in the hydrosphere. 

The elucidation of the molecular genetics RXI has had a major impact on our understanding of stratum corneum turnover. Individuals with RXI lack an enzyme, cholesterol sulfatase,3,4 which catalyzes the transformation of cholesterol sulfate (CS) to cholesterol and free sulfate. As a result there is an accumulation of CS in the stratum corneum intercellular space. Possible mechanisms by which this change in intercellular lipid composition of the stratum corneum can cause disturbances in desquamation, leading to ichthyosis, will be discussed later. 

The mixture was sonicated to eliminate aggregates. A polystyrene latex with a broad distribution was obtained from Kodak. This distribution had been characterized previously by electron microscopy, ultra centrifuge and Coulter counter. A monodlsperse, surfactant free, sulfated, polystyrene standard and a mixture of 10 such monodlsperse standards were purchased from Interfaclal Dynamics Corporation. A polyvinyl chloride latex with a broad distribution was donated by B. F. Goodrich. This sample had been characterized by Joyce Loebl disc centrifuge. These samples were diluted to 0.01% solids and sonicated to eliminate aggregates. 

The free sulfate ion is tetrahedral (Td), but when it functions as a unidentate ligand, the coordinated oxygen atom is no longer equivalent to the other three and the effective symmetry is lowered to Civ. Since the M—O—S chain is normally bent, the actual symmetry is even lower, but this perturbation of C3 symmetry does not measurably affect the ir spectra. When two oxygen atoms become coordinated, either to the same metal ion or to different ones, the symmetry is lowered still further to C2 . 

When sulfate ions form complexes in solution having a symmetry, the triply degenerate (F) mode at 1100cm (V3 in Table 5) splits into two bands. Under 2 the same mode splits into three bands [103, 115]. Besides this, in both cases a totally symmetric mode centered at about 980cm (V in Table 5), which is only Raman-active under the symmetry, becomes infrared-active. Consequently, in the spectral range above 900cm" free sulfate should present three modes under a C3V symmetry and four modes under a Czv symmetry. Whether the IR-active modes for the free ions under a given symmetry are also active for the adsorbed species depends on the orientation of the dynamic dipole moment with respect to the surface. 

A few years later, Jorpes confirmed much of the work done liy Charles and Scott. Heparin was purified by their procedure and, after. several successive treatments with Lloyd s reagent, the product was found to contain 1.64% of nitrogen. The presence of sulfur (as both bound and free sulfate), inorganic ash, uronic acid, hexosamine, and acetic acid was reported. Electrodialysis of the purified heparin removed free sulfate, and afforded a highly active preparation which could be precipitated as an amorphous brucine salt. ... 

The donor of the sulfate group in the compounds just mentioned i.s 3-phos-phoadenosine-5 -phosphDsuIfatie (PAPS). The structure of PAPS and its synthesis from ATP and free sulfate appear in Figure 10.54, FAI is used as a substrate by sulfotransferases. PAPS is synthesized in the cytoplasm and then transported into the Golgi, where it participates in the sulfation of maeromolcculcs destined for secretion from the cell. 

Free sulfate occurs in the plasma at concentrations of 1 to 2 mAf, The sulfate in the plasma and glomerular filtrate has been a concern for those interested in calcium status. Consumption of high-protein diets leads to increases in urinary calcium levels. This effect has been attributed, in part, to the catabolism of sulfur amino adds to yield free sulfate. The sulfate forms a complex with the calcium in... 

Piperazine Estrone Sulfate (3-Sui.FOxv-E iTiu-l,3,5(l0)-TRIEN-17-ONF. Piperazine Salt), USP. All the estrone 3-.sulfate salts have the obvious pharmaceutical advantage of increased water solubility and better oral absorption. Acids convert the salts to the free 3-sulfate esters and cause some hydrolysis of the ester. This does not seem to affect absorption adversely, but precipitation of the free sulfate esters in acidic pharmaceutical preparations should be avoided. The dibasic piperazine molecule acts as a buffer, giving it somewhat greater stability. 

According to (1) and (2), the addition of sulfuric acid to the solution decreases the concentration of free sulfate ions due to the... 

Similar EQCM measurements in the additive-free Cu(II)-En sulfate solution showed that Cu(II) reduction occurs at a low rate, while chloride additive of 0.5 mmol L 1 increases the rate of Cu(II) reduction ca. twice as compared with the additive-free sulfate solution. About sevenfold higher rate of Cu(II) reduction compared with additive-free sulfate solution and ca. fourfold higher in comparison with 0.5 mmol L 1 chloride additive is achieved in solution with KBr additive at the same concentration. Iodide additive at the same concentration increases the rate of Cu(II) reduction by the factor of approximately 20 compared with the additive-free sulfate solution. These data also clearly show that the halide ions even at low concentration facilitate Cu(II) ion reduction, which in ethylenediame solutions at pH > 5 exist mainly (>99%) as CuEn + complex [29]. Accelerating effect of halide additives on Cu(II) reduction rate in sulfate solution corresponds to the increase in adsorption ability of halides. The acceleration of Cu(II) reduction rate might be explained by either the displacement of inhibiting species, for example, adsorbed ethylenediamine, or preventing from... 

Sulfur-35 is the only long-lived radioactive isotope of sulfur and it may be produced by the direct neutron irradiation of elemental sulfur S (n,7)S . However, the specific activity attained is quite low even in high-neutron fluxes. It is preferable to irradiate potassium chloride and take advantage of the reaction CP (n,p)S . Four weeks irradiation of ten grams of potassium chloride in a thermal-neutron flux of 10 neutrons cm. sec. yields about 5 millicuries of which when dissolved in water is isolable as carrier-free sulfate ion. Nevertheless, the isotopes CP , P , K, and Na are concurrently produced in the neutron irradiation of potassium chloride, and a chemical... 

The free sulfate ion belongs to the liigh-symmetry point group Tj. Of the four fundamentals, only v- and P4 are infrared active. If the symmetry of the ion is lowered by complex formation, the degenerate vibrations split and... 

The [Fe(CN)5S03] ion has been prepared and characterized as a sodium salt (112). By reacting with one equivalent of the oxidizing agents [Ir CleJ and [Fe (CN)6] , it can be oxidized to the Fe(III) analogue (113), as also observed with excess S20 (114). An exploration of the reactions of the Fe(III) complex with excess oxidant leads to free sulfate, with the intermediacy of ill-characterized colored intermediates (113). 

Furthermore, liposomes provided the same bioavailability as the free sulfate, adding the advantage of being coated with a phospholipid membrane, which kept the iron from contacting with the other components of food, thus preventing undesirable interactions (Boccio et al., 1997 Uicich et al., 1999 Lysionek et al., 2000,2002 Shuqin and Shiying, 2005). 

The spectrum at 25°C corresponds to a biphased sample, and displays a marked splitting of the V3 mode, which we attribute, on the one hand, to relatively free sulfate ions in o.33[Cu-Cr-S04l3j (1100 cm h and, on the other hand to monodentate sulfates in [Cu-Cr-S04]jfj (1184 and 1100 cm h- A major difference appears for... 

The use of porphyrin complexes for the electrocatalytic detection of 8O2 is limited. Iron and titanium porphyrin peroxo complexes (TPPFe-O-FeTPP or TiP(02)) interact with 8O2 to give sulfato complexes of the porphyrins or to give free sulfate Carballo et al. showed that NiPPIX polymerized on GCE catalyzed the oxidation of 8O2, and the modified electrode was stable under hydro-dynamic conditions of a flow cell . ... 

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