The esterified plasma fatty acid profile is altered in early HIV-1 infection

The online version of the original article can be found at     

Amino-acids in humic,nitrohumic and nitrofuvic acids from coal

The humic acids, HA, extracted from a Spanish lignite and the nitrohumic acids, NHA, and nitrofulvic acids, NFA, extracted from the same lignite after its nitration, are hydrolysed with 6N HCI under reflux. The α-amino acids present in the hydrolysates are determined and thirteen α-amino acids are identified. The amounts of nitrogen in the amino-acids released by the hydrolysis increase according to the sequence: NFA > NHA > HA.     

Alumina and Alumina/Zirconia Multilayer Composites Obtained by Slip Casting

The slip casting technique has been revealed as a powerful method to obtain multilayer composites close to theoretical density. From zeta potential and viscosity measurements of Al₂O₃ and Al₂O₃/ZrO₂ (4 vol% ZrO₂) suspensions, the corditions for the preparation of multilayer composites by slip casting have been determined. A microstructural analysis of the different layers by scanning electron microscopy is also reported.     

STEADY AND NON-STEADY STATE MODELING OF TUBULAR FIXED BED REACTORS

In this work a detailed non-steady state two dimensional heterogeneous model for a non-isothermal, non-adiabatic packed bed tubular reactor is discussed. The model has the following features: i) axial and radial heat and mass dispersion, ii) heat transfer balance for the cooling fluid, iii) comprehensive treatment of the convective term, iv) spatially-dependent physical parameters, v) radial porosity and velocity profiles. Results are given, for both steady and non-steady state situations, in the context of an industrial unit for phthalic anhydride production. Co-current flow of reactive and cooling mediums is assumed.     

EXPERIMENTAL STUDIES OF NUCLEATION PHENOMENA WITHIN THERMAL BOUNDARY LAYERS—INFLUENCE ON CHEMICAL VAPOR DEPOSITION RATE PROCESSES

In carrying out partial vapor condensations using actively cooled surfaces it is known that 'mist' formation can occur within thermal boundary layers (Rosner and Epstein, 1968), dramatically modifying total deposition fluxes. Using a combination of flash-evaporation (Rosner and Liang, 1986) and laser probing techniques, we report new experimental results on binary alkali salt (K₂SO₄ + Na₂SO₄) deposition from combustion gases showing that the deposition rate of potassium sulfate first increases with the addition of sodium sulfate until the concentration of Na₂SO₄ reaches a (target surface temperature dependent) 'threshold' value. Further increases in the concentration of Na₂SO₄ dramatically decrease the total deposition rate of K₂SO₄, implying that potassium sulfate-containing microdroplets are formed within the thermal boundary layer, which, despite their thermophoretic drift toward the target, are not collected as effectively as the 'parent' K₂SO₄-vapor species. Laser light scattering measurements clearly reveal that suspended particles exist near the deposition surface under these conditions. Our experimental results on mass transfer rate and light scattering are consistent with those predicted using laminar boundary layer theory (Castillo and Rosner, 1989b) coupling both binary salt vapor deposition with particle vapor scavenging and deposition. Comparisons of our observed mist onset conditions (implying critical supersaturations near unity) with those expected using homogeneous nucleation theory suggest that the binary alkali sulfate mist nucleation mechanism is, instead, heterogeneous, even in our relatively 'clean' combustion products. Because of the; well-known vapor pressure reduction phenomenon associated here with the formation of non-ideal solutions, binary systems are shown to provide convenient 'vehicles' to investigate BL mist formation onset conditions and CVD-rate consequences without requiring the more extreme surface coolings characteristic of unary condensible vapor systems. An understanding of this dramatic phenomenon, obtained via such laboratory experiments and calculations, will allow its inclusion in future deposition rate calculations of engineering importance.     

Cyclic fatty acid monomer: Isolation and purification with solid phase extraction

The application of a combined solid phase extraction (SPE)/clean-up procedure to the isolation of a purified fraction containing all the monomeric cyclic fatty acid methyl esters is described. Extraction of the nonpolar lipid components from nonurea-adducting (NUA) filtrates is performed on a reverse phase octadecyl bonded silica minicolumn. Stepwise elution of the SPE-retained materials through silica gel using several solvents allowed the separation of a pure fraction containing the cyclic monomers that can be used for a more reliable quantitative estimation of these compounds in edible fats and oils.     

Chemical synthesis and spectroscopic characteristics of C18 1,2-disubstituted cyclopentyl fatty acid methyl esters

The chemical synthesis of methyl 9-(2′-n-butylcyclopentyl)nonanoate and methyl 10-(2′-n-propylcyclopentyl)-decanoate was performed using a Wittig reaction between 2-alkylcyclopentanones and the corresponding ω-carbomethoxyalkyl triphenylphosphonium bromides. The intermediate alkylcyclopentylidene alkanoate esters were isolated from the reaction mixture, characterized by spectrometric methods, and then catalytically hydrogenated to the desired cyclopentyl esters. Gas chromatographymass spectrometry (GC-MS) showed that the final products contained a mixture oftrans- andcis-ring isomers with small amounts of other cyclic by-products. The GC-retention features, the mass fragmentation pattern, and the spectroscopic characteristics of both the final and the unsaturated intermediate products are discussed.     

Time-Temperature-Transformation Curves for Kaolinite-α-Alumina

The C-shaped time-temperature-transformation curves (T-T-T curves) of cristobalite formation and the L-shaped T-T-T curves of α-alumina reaction were established for a high-purity kaolinite-α-alumina mixture during heating. The results revealed that cristobalite formation in kaolinite was retarded by the presence of α-alumina between 1250° and 1350°C and was totally prohibited above 1380°C due to the reaction of kaolinite with α-alumina to form secondary mullite. The reaction of α-alumina with kaolinite was initiated at about 1250°C. It became quite extensive above 1380°C and was extremely fast at 1600°C and above, indicating the strong effect of the eutectic liquid formation at ∼1587°C in silica-alumina. The effectiveness of the established T-T-T curves was demonstrated and discussed.     

Inhibition of potato cyst nematode hatch by lignans fromBupleurum salicifolium (Unbelliferae)

A series of lignans fromBupleurum salicifolium Soland (Umbelliferae) were tested for nematostatic activity on the cysts and freed secondstage juveniles of the potato cyst nematodesGlobodera rostochiensis andG. pallida. None of the six lignans tested—bursehernin, matairesinol, syringaresinol, the novel product buplerol, guayarol, and a derivative, nortrachelogenin triacetate—showed nematicidal activity in an in vitro analysis with second-stage juveniles, but significant differences were noted when the lignans were assayed for nematostatic activity as cyst hatching inhibitors. Bursehernin and matairesinol showed the greatest activity, at concentrations of 50 ppm. This is the first known instance of a natural product inhibiting the hatch of the nematodeG. pallida. The HID (hatching inhibiting dose) of bursehernin was estimated, and some conclusions were drawn about the structure-activity relationships of the lignans under study.     

Responses by amphisbaenianBlanus cinereus to chemicals from prey or potentially harmful ant species

We tested the ability of amphisbaenians (Blanus cinereus) to discriminate between odors of ant species selected as prey (Pheidole pallidula) and odors of potentially harmful ant species (Messor barbarus) that are avoided. Tongue-flick rate to swabs impregnated with ant odors, cologne, or deionized water differed among treatments, showing that amphisbaenians were able to discriminate ant species odors. Amphisbaenians showed an aggressive response and bit applicators bearing the odor of harmful ants, while the odor of prey ants did not elicit bites to swabs. The possible evolutionary advantage of identifying and avoiding harmful ants is discussed in relation to the fossoriality of amphisbaenians.