1,721,171 research outputs found
A standardized protocol for continuous subcutaneous insulin infusion in the peripartum period in women with type 1 diabetes
No full textObjectives and methods. Metabolic control must be optimized to prevent maternal-neonatal complications during and after delivery. The primary aim of this study was to provide a standardized protocol for continuous subcutaneous insulin infusion (CSII), with or without real-time continuous glucose monitoring (RT-CGM), during delivery in pregnant type 1 diabetic women. This procedure was based on a retrospective multicenter observational study in which CSII was used around the time of delivery by women already instructed on its use during pregnancy. Three basal insulin rates were established, depending on the capillary blood glucose level (CBG): profile A, last basal rate in use before delivery; profile B, half of profile A; profile C, 0.1-0.2 U/h, for CBG < 70 mg/dl, activated just before anesthesia or at the beginning of active labor. An alternative intravenous insulin protocol (IVP) was applied in case of complications or sudden metabolic deterioration. Primary outcomes were CBG in the target range (70-140 mg/dl) throughout delivery and the percentages of women managed with the IVP. Results. The study comprised 65 pregnant women with diabetes: 56 (86%) had cesarean section, 9 (14%) spontaneous/ induced vaginal delivery. Mean CBG was 102 ± 31 mg/dl at time 0; 109 ± 42 mg/dl at 30 min; 120 ± 48 mg/dl at 60 min; 99 ± 34 mg/dl at 24 h. Mean basal rate during delivery was 0.6 ± 0.4 U/h (profile B). Mean CBG was lower in the RT-CGM group than with CSII alone: 80 ± 14 mg/dl vs 111 ± 32 mg/dl at 0 min (p < 0.01); 79 ± 11 mg/dl vs 109 ± 42 mg/dl at 30 min (p < 0.02); 98 ± 20 mg/dl vs 125 ± 51 mg/dl at 60 min (p = ns). There were 11 cases (17%) of neonatal hypoglycemia, 9 of them transient. No women had to switch to IVP. No major differences were observed in relation to the delivery procedure. Conclusions. CSII is feasible and safe during delivery in selected women who have been appropriately instructed. RT-CGM can help achieve better maternal peripartu
Thermal properties and devitrification behaviour of (2.5-x)CaO.x/3Y(2)O(3).2SiO(2)
No full textThe effect on thermal properties and non-isothermal devitrification of substituting CaO by Y2O3, in a glass of composition 2.5 CaO.2SiO(2) was studied. The glass samples were submitted to thermal analysis (DTA) and X-ray diffraction analysis. The trends with the composition of the glass transformation, T-g, softening, T-s temperature and the activation energy of crystal growth, E-c, can be explained on the basis of the increase of the structural rigidity when Ca2+ ions are substituted by Y3+ ions; stronger bonds to the oxygen are, indeed, expected. In all the devitrified samples CaO.SiO2 crystals form together with a secondary calcium silicate phase. The pattern of the Y2O3 free glass shows that the alpha CaO.SiO2 is also formed in the temperature range 900-1000 degrees C. When x = 1.0 a new, crystalline phase appears, which could not be identified by means of JCPDS cards. The activation energy for crystal growth was E-c = 640 +/- 25.1 kJ/mole, regardless of composition. Devitrification involved a mechanism of surface nucleation: however, as the samples softened and sintered before devitrifying, surface nuclei behaved as bulk nuclei. (C) 1997 Elsevier Science B.V
An ionic conduction mechanism for the AgI doped glasses of the system Ag2O-B2O3
No full textIn this paper it is proposed that, as long as the glasses of the system Ag2O-B2O3-AgI are demixed on a very fine scale into a silver borate matrix and AgI microdomains, their activation energy for electrical conduction can be considered an average value of the two phases present. These values are taken to be equal to those of silver iodide and of the corresponding undoped silver borate In this light it is expected that, in the compositional range considered the following relation holds: E-sigma/E-sigma ma = R; where E-sigma and E-sigma ma are the activation energies, respectively, of the doped and undoped glass and R is the fraction of Ag+ added as Ag2O. Deviations from this 'ideal' behaviour are attributed to the presence, at the boundary of the two phases, of Ag+ in mixed neighbour sites, that is, surrounded by negatively charged structural units of both phases. This approach appears to be successful in explaining the compositional dependence of both E-sigma and the glass transformation temperature, T-g, of the studied system
Composition dependent electrical conductivity of (1-y)[(1+x)Ag2O.P2O5]yAgI glasses in the range 0.55<=y<=0.70, 0<=x<=0.4
No full textGlasses of the following general formula were prepared in order to investigate their electrical and thermal properties: (1-y) [(1+x) Ag2O.P-2 O-5]yAgI, 0.55 less than or equal to y less than or equal to 0.70, 0 less than or equal to x less than or equal to 0.4. Experimental data confirm that, as reported in the literature, the increase of the AgI content makes the electrical conductivity, sigma, increase and the glass transformation temperature T-g decrease. The increase of sigma is primarily due to the decrease of the activation energy for conduction, E(sigma). The results can be interpreted on the basis of the model reported in the literature of a glass demixed in AgI microdomains and a phosphate matrix. They suggest that the Ag+ migration paths also involve sites other than the ones near I- ions and that E(sigma) for the AgI doped glasses can be considered an average of the values relative to the various phases present. As it happens in glasses poorer in AgI content, a linear relation is observed when the ratio E(sigma)/E(sigma ma) of the activation energies of AgI doped, E(sigma) and undoped, E(sigma ma) glasses is plotted against the fraction of Ag+ ions introduced as Ag2O
The Effect On Thermal and Electrical-properties of the Addition of Ga2O3 To Glasses of the Ag2O-P2O5-AgI System
No full textGlasses of the following general formula were prepared in order to investigate their electrical and thermal properties: 0.65((1 + x)Ag2O.yGa2O3.(1-Y)P2O5). 0.35 AgI (0 less-than-or-equal-to x less-than-or-equal-to 0-6) (0 less-than-or-equal-to y less-than-or-equal-to 0.2). Experimental data indicate that the substitution of Ga2O3 by P2O5 increases both the glass transformation temperature T(g) and the electrical conductivity sigma. It has been hypothesised that tetrahedral GaO4 groups are in equilibrium with units in which Ga+3 ions have higher coordination (possibly six as in the pure Ga2O3 structure). The dependence on composition of the parameters of the Arrhenius type equation of sigma are explained on the basis of the reported structural model of AgI microdomains in a silver phosphate matrix and on the basis of the diffusion path model for ionic conduction. Experimental results suggest that Ag+ migration paths involve sites other than the ones near I- ions
Crosslinking liquid crystalline polyesters with allyl group as lateral substituent: thermal and UV activation.
No full textLiquid crystalline polymorphism in a new class of semiflexible polyesters containing a 2-phenyl-benzoxazole group
No full textThe synthesis and phase behaviour of a new class of semiflexible polyesters based on aliphatic dicarboxylic acids (from octanedioic to tetradecanedioic acid) and 2-(4-hydroxy-phenyl)-6-hydroxy benzoxazole are
described. All the polymers synthesized are mesogenic and show a nematic or a smectic A phase (or both) depending on the length of the flexible spacer, the smectic mesomorphism being favoured for longer spacers. For the smectogenic polymers, the observed layer periodicity is equal to about half the length of the monomeric unit. A possible explanation is the occurrence of a regularly intercalated packing of the chains, with lateral matching of aliphatic and aromatic molecular sections
Mesophasic behaviour of new semiflexible polyesters containing a 2-phenyl-benzoxazole group
No full textLiquid crystalline polymorphism in new semiflexible polyesters containing 2-phenyl-benzoxazole group
No full text- …
