Photooxidative treatment of sulfurous water for its potabilization

The feasibility of potabilization of sulfurous water was investigated by photochemical oxidation processes using a batch photoreactor and a continuous-flow photoreactor, equipped with UV lamps of 1000 W and 1500 W, respectively. Additionally, two advanced processes of oxidation were applied i.e. with a use of a UV light/H2O2/air and UV light/H2O2/O3/air. These two processes were compared for their efficiency to the direct oxidation process where ozone is used in the absence of UV light. Results obtained for both advanced processes showed better oxidation than takes place by ozone in the absence of UV light. After the photooxidation processes, different processes for the absorption or precipitation of sulfates were investigated to comply with the World Health Organization (WHO) norm that demands a limit of < or =250 mg L(-1) of SO4(2-) in drinking water. Additionally, reverse osmosis was simulated using Osmonics Inc. software to predict the feasibility of lowering the salt concentration below WHO limits.     

The anomalous Mössbauer fraction of ferritin and polysaccharide iron complex (PIC)

Mössbauer studies of the ubiquitous protein molecule ferritin and its synthetic biomimic polysaccharide iron complex (PIC) exhibit an anomaly in the Mössbauer spectrum wherein the recoil free fraction orf-factor has a sharp drop with respect to temperature as the temperature rises above 30 K for mammalian ferritin and 60 K for PIC. The anomaly coincides with the disappearance of hyperfine splitting, which is due to superparamagnetic relaxation above the blocking temperature. Different absorbers were used to experimentally investigate the effect of absorber thickness on the Mössbauer spectrum. The anomaly persists for thin absorbers. Also, spectra treated with FFT procedures to eliminate the thickness effect still exhibit this anomaly. Motion of the core with respect to the protein shell was also eliminated as a possible source for this phenomenon, by comparing the Debye temperature obtained from the temperature dependence of thef-factor and the isomer shift. A comparison of the magnetic anisotropy constants from magnetization studies with those obtained by relating the hyperfine fieldH of the Mössbauer spectra to the fluctuations of the magnetization imply that the ferritin and PIC molecules possess magnetic anisotropy energy which may not be strictly uniaxial. This, we believe, may be intimately connected with the mechanism causing thef-factor anomaly.This work was carried out in partial fulfilment of the requirements of the PhD degree at Tufts University.     

Evaluation of contributions to the uncertainty of cholesterol determination in human serum by means of gas chromatography/(quadrupole-) mass spectrometry

 The uncertainty budget of the determination of cholesterol in a reference material (freeze-dried human serum) by isotope dilution mass spectrometry (IDMS) was evaluated. Measurements were run on a GC/quadrupole MS. A nested experimental design combined with a corresponding model for the analysis of variance (ANOVA) revealed the components making up the total uncertainty of the determinations. The coefficient of variation (CV) of the sole GC/MS-step was 0.47%, while that of the sample preparation including hydrolyzation, extraction and derivatization was 0.84%. This made the in-laboratory (overall) CV 0.96%. In addition, there was a vial-to-vial effect of 1.00% probably due to both inhomogeneity of the pooled material and lack of reproducibility of the filling procedure (including freeze drying) of the supplier as well as the reconstitution prior to use in the laboratory. These contributions sum up to an overall CV of a single determination of about 1.4%. Received: 17 October 1996/Revised: 14 November 1996/Accepted: 18 November 1996     

New improvements in oligonucleotide synthesis by use of the p-nitrophenylethyl phosphate blocking group and its deprotection by DBU or DBN

Phosphate protection in the phosphotriester approach is improved by the new, versatile p-nitrophenylethyl group due to its stability in the condensation step and its clean removal by DBU and DBN respectively.     

Nucleotide. XV. Synthese und Eigenschaften von 2′-O-t-Butyldimethylsilyl-5′-O-monomethoxytritylribonucleosid-3′-phosphotriestern,Ausgangssubstanzen für Oligonucleotid-Synthesen

Nucleotides. XV. Synthesis and Properties of 2′O-t-Butyldimethylsilyl-5′-O-monomethoxytritylribonucleoside-3′-phosphotriesters, Starting Materials for Oligonucleotide Syntheses The syntheses of two types of fully blocked ribonucleoside 3′-phosphotriesters 6–14 have been achieved in excellent yields from 2′-O-t-butyldimethylsilyl-5′-O-monomethoxytrityl-ribonucleosides 1–5 by phosphorylation with 2-chloro- and 2,5-dichlorophenylphosphorodichloridate respectively and subsequent treatment by cyanoethanol to 6 , 8 , 10 , 12 and 14 and by p-nitrophenylethanol to 7 , 9 , 11 and 13 . These phosphotriesters are valuable starting materials for oligonucleotide syntheses due to the fact that the corresponding phosphotriesters 15–23 with free HO? C(5′) could be obtained by detritylation and the 3′-phosphodiester triethylammonium salts 24–32 by deblocking of the cyanoethyl and the 2,5-dichlorophenyl group respectively. All newly synthesized compounds have been characterized by UV.-and NMR.-spectra as well as C, H, N elementary analyses.     

Glycosylidene Carbenes. Part 18. Insertion of glycosylidene carbenes into the Sn?H bond of tributyl- and triphenylstannane: A synthesis of stannoglycosides

Insertion of the glycosylidene carbenes, derived from the gluco- and the manno-diazirines 1 and 2 , into the Sn? H bond of R₃SnH (R = Bu or Ph) leads to the fully substituted stannoglycosides 3 – 8 (53–77%). The 1,2-cis-configurated products are formed preferentially (α-D /β -D ranges from 2.5:1 to 5.1:1 with 1 , and 1:1.3 to 1:4.2 with 2 ). Relative to CH₂Cl₂, THF favors formation of the equatorial Sn-glycosides. The stannylated (benzyloxy)glucals 9 and 10 were isolated as side products. The reaction of 1 with (Bu₃Sn)₂ yielded 9 (17% in CH₂Cl₂; 36% in CCl₄) together with the azines 11 and the benzyloxyglucal 12 . NMR Data of the Sn-glycosides 3 – 8 show evidence for an anomeric effect, ¹J(C(1),H) being larger in the axial and ¹J(Sn,C(1)) larger in the equatorial anomers.     

Stochastic linear maps and transition probability

Some aspects of the transition probability P(, ) between states , on unital ^*-algebras are discussed. It is shown that P increases under the action of any stochastic linear map T, i.e., P(T, T)P(, ). Some properties of P are derived in starting from a recently-proved characterization of the quantity in question.     

New Entrance Optics for Solar Spectral UV Measurements

The investigation of the impact of solar UV radiation on the biosphere requires spectral measurements of solar UV radiation of high accuracy. However, the accuracy of current measurements is limited, and this can partly be attributed to the entrance optics of the instruments used for these examinations. The angular response of spectro-radiometers measuring spectral global UV irradiance should be given by the cosine of the incidence angle. In-tercomparison campaigns have shown that deviations from this ideal cosine response lead to uncertainties in solar measurements of more than 10%. Here we present recently developed entrance optics that reduce these uncertainties to ±4% in the UV. The new entrance optics have been characterized with respect to their angular response, transmission, weather durability, fluorescence and dependence of the angular response on wavelength and polarization. Solar spectroradiometric measurements carried out with the new optics were compared with simultaneously performed measurements of a second spectroradiometer that was equipped with a conventional diffuser. The deviations of up to 12% between both systems are quantitatively explained to within 3%.     

Nucleotides. Part XXVIII. Chemical syntheses of the 2′-5′-cordycepin-trimer core

The chemical synthesis of 3′-deoxyadenyly-(2′-5′)-3′-deoxyadenylyl-(2′-5′)-3′-deoxyadenosine ( 30 ; trimeric cordycepin) is described by three different routes using various protecting groups and applying the phosphotriester approach. The intermediates have been isolated and characterized by elemental analyses and spectroscopic means. High yields of 30 have been obtained on deprotection making this biologically very active compound available in preparative scale.     

Metallorganische Verbindungen des Kupfers XIII. Kupfer(I)-chlorid-Komplexe winkelgespannter Cycloheptine Synthesen und Röntgenstrukturanalysen

The strained cycloheptynes 2a, 2b and 2c react with copper(I) chloride to form the dinuclear complexes [CuCl(cycloheptyne)]₂ 3a, 3b and 3c respectively. X-ray diffraction studies on all three compounds 3 show an increase in strength of the copper-alkyne bond with increasing deformation of the alkyne moiety from the ideal 180°. Thus going from the least strained alkyne (2c) to the most strained one (2a), the Cu-C bond lengths in the corresponding complexes decrease from 197.5 pm (3c) to 194.9 pm (3a). The C≡C-C angles increase from 145.6° (3a) over 147.4° (3b) to 151.6° (3c).

Zusammenfassung

Die gespannten Cycloheptine 2a, 2b und 2c reagieren mit Kupfer(I)—chlorid unter Bildung der zweikernigen Komplexe [CuCl(cycloheptin)]₂ 3a, 3b und 3c. Röntgenstrukturanalysen von allen drei Verbindungen 3 zeigen, daβ die Stärke der Kupfer—Alkin-Bindung zunimmt je mehr das ganze Alkinsystem vom idealen 180°-Winkel abweicht. Geht man vom am wenigsten gespannten Alkin (2c) zum gespanntesten (2a), so nehmen die Cu-C-Bindungslängen in den entsprechenden Komplexen von 197.5 pm (3c) auf 194.9 pm (3a) ab. Die C≡C-C-Winkel werden von 145.6° (3a) über 147.4° (3b) nach 151.6° (3c) hin gröβer.