Functional water-insoluble polymers with ability to remove arsenic(V)

Three resins were synthesized through radical polymerization: poly[(ar-vinylbenzyl)trimethylammonium chloride] P(VBTA), poly[(ar-vinylbenzyl)trimethylammonium chloride-co-acryloylmorpholine] P(VBTA-co-AM), and poly[(2-acryloyloxy) ethyltrimethylammonium chloride-co-acryloylmorpholine]. The removal capacity for arsenic under different conditions was studied and compared with a commercial resin Amberlite IRA 400-Cl. The arsenic sorption capacity of the resins at the optimum pH showed the following order: Amberlite 95.5% (27.1 mg/g, 0.36 mmol/g), P(VBTA) 92.6% (16.3 mg/g, 0.22 mol/g), P(VBT-co-AM) 90.4% (21.5 mg/g, 0.29 mmol/g), and P(AETA-co-AM) 87.3% (21.7 mmg/g, 0.29 mmol/g).     

Endoglin modulates cellular responses to TGF-beta 1

Endoglin is a homodimeric membrane glycoprotein which can bind the beta 1 and beta 3 isoforms of transforming growth factor-beta (TGF-beta). We reported previously that endoglin is upregulated during monocyte differentiation. We have now observed that TGF-beta itself can stimulate the expression of endoglin in cultured human monocytes and in the U-937 monocytic line. To study the functional role of endoglin, stable transfectants of U-937 cells were generated which overexpress L- or S- endoglin isoforms, differing in their cytoplasmic domain. Inhibition of cellular proliferation and downregulation of c-myc mRNA which are normally induced by TGF-beta 1 in U-937 cells were totally abrogated in L-endoglin transfectants and much reduced in the S-endoglin transfectants. Inhibition of proliferation by TGF-beta 2 was not altered in the transfectants, in agreement with the isoform specificity of endoglin. Additional responses of U-937 cells to TGF-beta 1, including stimulation of fibronectin synthesis, cellular adhesion, platelet/endothelial cell adhesion molecule 1 (PECAM-1) phosphorylation, and homotypic aggregation were also inhibited in the endoglin transfectants. However, modulation of integrin and PECAM-1 levels and stimulation of mRNA levels for TGF-beta 1 and its receptors R-I, R-II, and betaglycan occurred normally in the endoglin transfectants. No changes in total ligand binding were observed in L-endoglin transfectants relative to mock, while a 1.5-fold increase was seen in S-endoglin transfectants. The degradation rate of the ligand was the same in all transfectants. Elucidating the mechanism by which endoglin modulates several cellular responses to TGF-beta 1 without interfering with ligand binding or degradation should increase our understanding of the complex pathways which mediate the effects of this factor.     

Structure of complex cell wall polysaccharides isolated from Trichoderma and Hypocrea species

The structure of fungal polysaccharides isolated from the cell wall of Trichoderma reesei, T. koningii, and Hypocrea psychrophila, have been investigated by means of chemical analyses and 1D and 2D NMR spectroscopy. The polysaccharides have an irregular structure, idealized as follows: [formula: see text] The proportions of the different side chains vary from a species to another, being n above some three times larger in H. psychrophila than in T. reesei or T. koningii.     

Current Mode Techniques for Sub-pico-Ampere Circuit Design

In this paper we explore the low current limit that standard CMOS technologies offer for current mode based VLSI designs. We show and validate a reliable circuit design technique for current mode signal processing down to fempto-amperes. We will take advantage of specific-current extractors and logarithmic current splitters to obtain on-chip sub-pA currents. Then we will use a special on-chip saw-tooth oscillator to monitor and measure currents down to a few fempto-amps. This way, sub-pA currents are characterized without driving them off-chip, nor requiring expensive instrumentation with complicated low leakage setups. A special current mirror is also introduced for reliably replicating such low currents. As an example, a simple log-domain first-order low-pass filter is implemented that uses a 100 fF capacitor and a 3.5 fA bias current to achieve a cut-off frequency of 0.5 Hz and using an area of 12 × 24.35 μm² in a standard 0.35 μm CMOS process. A technique for characterizing noise at these currents is described and verified. Also, temperature dependence of leakage currents is measured as well.     

Synthesis, characterization, and properties of polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II)

SUMMARY Polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II) metal ions are synthesized. These compounds are characterized by FT IR, UV-vis spectroscopy, and thermal analysis. The electrical conductivity measurements are carried out. These demonstrate that at temperature close to 130°C the electrical conductivity increased to values near to the semiconductor range. The PM3 calculations are also carried to study the geometry of the polychelates. Received: 1 November 2000/Revised version: 20 March 2001/Accepted: 21 March 2001     

Effect of prazosin on the function of the teat sphincter in lactating cows

Oxytocin was infused for 60 min into the jugular vein of 8 lactating cows with full udders before milking. Under these circumstances milk loss occurred spontaneously in 3 cows and was evoked in 5 cows by reducing pressure around one teat (-30 cm water) using a plethysmographic chamber. Milk loss was measured continuously. The postsynaptic alpha-blocking agent prazosin ( PRZS ) injected either into the udder artery (2 or 5 mg) or into the jugular vein (200 mg) consistently induced a significant increase in milk leakage. It is suggested that PRZS effectively inhibits alpha-adrenoceptors in the teat sphincter muscles and thus promotes the action of beta-adrenoceptors, in this way inducing relaxation of the teat sphincter.     

Nanostructured hybrid ZnO thin films for energy conversion

We report on hybrid films based on ZnO/organic dye prepared by electrodeposition using tetrasulfonated copper phthalocyanines (TS-CuPc) and Eosin-Y (EoY). Both the morphology and porosity of hybrid ZnO films are highly dependent on the type of dyes used in the synthesis. High photosensitivity was observed for ZnO/EoY films, while a very weak photoresponse was obtained for ZnO/TS-CuPc films. Despite a higher absorption coefficient of TS-CuPc than EoY, in ZnO/EoY hybrid films, the excited photoelectrons between the EoY levels can be extracted through ZnO, and the porosity of ZnO/EoY can also be controlled.     

Study by scanning electron microscope of phosphorylated polyethylene resins

A study of surface area using specific resins for uranium from phosphorylated polyethylene has been made. A positive correlation between maximum capacities of the resins and surface area was found. The crosslinked resins with polyols present the best maximum capacities and high adsorption capacities. This is in agreement with the electron micrographs which give information about the adsorption process.     

Preovulatory rise of NGF in ovine follicular fluid: possible involvement in the control of oocyte maturation

Since nerve growth factor (NGF) is produced in vitro by granulosa cells after gonadotropin stimulation, the present research has been designed to investigate whether this neurotropin is involved in the events triggered by the gonadotropin surge that lead the follicle to ovulate a mature oocyte. To this aim, NGF levels in follicular fluid, collected before or 20 hours after the gonadotropin surge, was measured by ELISA. To evaluate whether NGF may have a non-neurotropic effect on follicle cells, the presence of NGF receptors was investigated by immunohistochemistry and further evaluated by analysing the tyrosine-phosphorylation pattern after NGF stimulation in vitro. The effect of NGF on the degree of cumulus expansion, cumulus-oocyte metabolic coupling, and meiotic maturation was finally studied by using the culture of follicle-enclosed oocyte. The results demonstrate that GnRH causes a dramatic rise of NGF in large follicles. Immunohistochemistry revealed a discrete positivity for trkA receptors localised in cumulus cells. Tyrosine phosphorylation pattern confirms that somatic cells are capable to transduce NGF signal. By contrast, all the oocytes examined were negative for trkA and did not change the phosphorylation pattern after NGF. In vitro NGF (100 ng/ml) induced a marked cumulus expansion and a progressive cumulus-oocyte uncoupling similar to that produced by gonadotropins. The addition of NGF also caused the resumption of meiosis in more than 70% of the oocytes analysed with an effect that is only slightly less pronounced than that of gonadotropins (80%). The increase in NGF secretion following gonadotropin surge suggests that this neurotropin may be involved in the control of oocyte maturation.     

Principal-component characterization of noise for infrared images

Principal-component decomposition is applied to the analysis of noise for infrared images. It provides a set of eigenimages, the principal components, that represents spatial patterns associated with different types of noise. We provide a method to classify the principal components into processes that explain a given amount of the variance of the images under analysis. Each process can reconstruct the set of data, thus allowing a calculation of the weight of the given process in the total noise. The method is successfully applied to an actual set of infrared images. The extension of the method to images in the visible spectrum is possible and would provide similar results.