Determination of carbon monoxide using a coated quartz crystal sensor

Carbon monoxide was detected and determined by a piezoelectric quartz crystal sensor coated with nickel(II)-phthalocyanine 50 % (v/v) solution in glycerine. Studies on the effect of temperature, flow rate, and some possible interferents were carried out. Calibration curves, sensor stability (lifetime) and the precision of measurements were also verified. The resulting selectivity is probably due to the coordinative binding between the electronically unsatured metal complexes and the analyte. The analytical curve is linear in the concentration range 0.10 to 1.0 % (v/v).

Desenvolvimento de um detector piezelétrico para cromatógrafo a gás interfaceado a microcomputador

A piezoelectric detector based on a commercial quartz crystal of 3.57MHz is shown. A PTFE cell attached to the GC-column outlet holds the polymer-coated crystal, whose terminals were removed. Two TTL oscillators (reference and sensor) are used and the beating of their frequencies is monitored through a home-made counter card inserted in a microcomputer. The original thermal conductivity detector was also interfaced, but through a 12-bit analog-to-digital converter. In spite of the well-known fact that QCM has low sensitivity at high temperatures, results show significant peak deformation for low temperatures. In addition, the phenomenon is also dependent on the chemical composition of the absorbent film besides instantaneous partial pressure and chemical composition of the analyte.

"In vivo" and "in vitro" demonstration of hemoglobin C crystals in non-splenectomized patients

We studied 12 Hb C carriers: 4 homozygotic Hb CC and 8 heterozygotic. We observed the presence of free crystals in the peripheral blood of the homozygotes but in none of the heterozygotes. However, after incubation with 3% NaCl we were able to detect crystals in the heterozygotes (Hb AC and Hb SC), and in the homozygotes (Hb CC). In patient 04 (P04) less crystals formation occurred due to inhibition of the process by the presence of elevated levels of Hb F (12.2%). All the homozygotic patients had a splenomegaly of 3 to 6 fingerbreadths.We believe that the spleen wears off with time, thus allowing the passage of crystals to the peripheral blood. This finding might be associated with splenic insufficiency without a reduction of its dimensions. Finally, the finding of crystals in the peripheral blood permitted the diagnosis of Hb C obviating the need for electrophoresis.

Comparative response to N, P and K of grain sorghum and corn: I. Distrophic quartz sand

The comparative response of three sorghum (E-57, TEY 101 and C- 102) and of three corn cultivars (HMD-7974, Centralmex and Piranão) to N, P and K applications was studied in a soil from Anhembi, SP, classifield as Distrophic quartz sand (AQd) was studied. Leaf analyses were made to assess the nutritional status of the two crops. Main conclusions were the following. 1. Sorghum yieldel more than corn; 2. Both sorghum and corn varieties showed different capacities to absorb N, P and K from the soil and to fertilizer application; 3. There was no response to K2O fertilization; 4. Only Piranão increased yield when suplemented with a mixture of micronutrientes; 5. Direct relationships between rates of N and P2O5 and yield and leaf content were found; 6. Direct relationships between rates of N and P2O5 and yield and leaf content were found; 7. The following leaf levels were considered to be adequate, respectively for sorghum and corn: N - 2,00 - 2,25%, 3,25 - 3,50%; P - 0,30 - 0,40, 0,45 - 0,50; K -2,00 - 2,50, 2,20 - 2,40%; Ca - 0,20 - 0,40, 0,44- 0,72% Mg - 0,25 - 0,40, 0,34 - 0,60%; S - 0,50 - 0,70, 0,72 -0,80; Cu - 7 - 10, 11 - 15%; Fe - 84 - 170, 98 - 125%; Mn - 58 - 72, 66 - 85%; Zn - 10 - 14, 18 - 22; critical levels, however, do very depending upon cultivar.

Estudo da síntese da zeólita MCM-71

A new kind of material, denominated MCM-71, was synthesized and characterized by several complementary techniques: X Ray Diffractometry, textural analysis by nitrogen adsorption, Scanning electronic microscopy and infrared spectroscopy. MCM-71 zeolite was successfully synthesized by hydrothermal synthesis in the presence of triethanolamine. Mordenite phase as impurity was not detected, otherwise quartz was observed. The MCM-71 sample obtained presented a BET surface area of 20 m²/g in the as synthesized form and of 85 m²/g in protonic form. By SEM was observed crystals with rectangular shape with average size of 2 x 0,2 x 0,05 µm and this crystals were agglomerated in spherical particles with average diameter between 14 and 24 µm.

Membrane proteins: functional and structural studies using reconstituted proteoliposomes and 2-D crystals

Reconstitution of membrane proteins into lipid bilayers is a powerful tool to analyze functional as well as structural areas of membrane protein research. First, the proper incorporation of a purified membrane protein into closed lipid vesicles, to produce proteoliposomes, allows the investigation of transport and/or catalytic properties of any membrane protein without interference by other membrane components. Second, the incorporation of a large amount of membrane proteins into lipid bilayers to grow crystals confined to two dimensions has recently opened a new way to solve their structure at high resolution using electron crystallography. However, reconstitution of membrane proteins into functional proteoliposomes or 2-D crystallization has been an empirical domain, which has been viewed for a long time more like "black magic" than science. Nevertheless, in the last ten years, important progress has been made in acquiring knowledge of lipid-protein-detergent interactions and has permitted to build upon a set of basic principles that has limited the empirical approach of reconstitution experiments. Reconstitution strategies have been improved and new strategies have been developed, facilitating the success rate of proteoliposome formation and 2-D crystallization. This review deals with the various strategies available to obtain proteoliposomes and 2-D crystals from detergent-solubilized proteins. It gives an overview of the methods that have been applied, which may be of help for reconstituting more proteins into lipid bilayers in a form suitable for functional studies at the molecular level and for high-resolution structural analysis.