Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

Influence of vacuum on the formation of porous polymer films via water droplets templating

10.1007/s00396-008-1954-3Colloid and Polymer Science287129-3

Maternal plasma concentrations of angiogenic/anti-angiogenic factors are of prognostic value in patients presenting to the obstetrical triage area with the suspicion of preeclampsia

OBJECTIVE: To determine if maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and -2 could identify patients at risk for developing preeclampsia (PE) requiring preterm delivery. STUDY DESIGN: Patients presenting with the diagnosis ‘rule out PE’ to the obstetrical triage area of our hospital at <37 weeks of gestation (n=87) were included in this study. Delivery outcomes were used to classify patients into 4 groups: I) patients without PE or those with gestational hypertension (GHTN) or chronic hypertension (CHTN) who subsequently developed PE at term (n=19); II): mild PE who delivered at term (n=15); III): mild disease (mild PE, GHTN, CHTN) who subsequently developed severe PE requiring preterm delivery (n=26); and IV): diagnosis of severe PE (n=27). Plasma concentrations of PlGF, sEng, sVEGFR-1 and -2 were determined at the time of presentation by ELISA. Reference ranges for analytes were constructed by quantile regression in our laboratory (n=180; 1,046 samples). Comparisons among groups were performed using multiples of the median (MoM) and parametric statistics after log transformation. Receiver operating characteristic curves, logistic regression and survival analysis were employed for analysis. RESULTS: The mean MoM plasma concentration of PlGF/sVEGFR-1, PlGF/sEng, PlGF, sVEGFR-1 and -2, and sEng in Group III was significantly different from Group II (all p<0.05). A plasma concentration of PlGF/sVEGFR-1 ≤ 0.05 MoM or PlGF/sEng ≤ 0.07 MoM had the highest likelihood ratio of a positive test (8.3, 95% CI 2.8–25 and 8.6, 95% CI 2.9–25, respectively), while that of PlGF ≤0.396 MoM had the lowest likelihood ratio of a negative test (0.08, 95% CI 0.03–0.25). The association between low plasma concentrations of PlGF/sVEGFR-1 (≤0.05 MoM) as well as that of PlGF/sEng (≤ 0.07 MoM) and the development of severe PE remained significant after adjusting for gestational age at presentation, average systolic and diastolic blood pressure, and a history of chronic hypertension [adjusted odds ratio (OR) = 27 (95% CI 6.4–109) and adjusted OR 30 (95% CI 6.9–126), respectively]. Among patients who presented <34 weeks gestation (n=59), a plasma concentration of PlGF/sVEGFR-1 <0.033 MoM identified patients who delivered within 2 weeks because of PE with a sensitivity of 93% (25/27) and a specificity of 78% (25/32). This cut-off was associated with a shorter interval-to-delivery due to PE [hazard ratio = 6 (95% CI 2.5–14.6)]. CONCLUSIONS: Plasma concentrations of angiogenic/anti-angiogenic factors are of prognostic value in the obstetrical triage area. These observations support the value of these biomarkers in the clinical setting for the identification of the patient at risk for disease progression requiring preterm delivery