Synthesis and characterization of mesoporous silica: laboratory exercises for students

Synthesis and characterization of SBA-15 were proposed as a laboratory course: linked series of exercises for graduate students. The standard preparation method was modified to fit a typical schedule of students’ classes, that is, 3-hours units every second week. The properties of materials obtained by different students’ groups were compared with the properties of materials obtained by means of a standard method

Social activation of local communities in Poland from the perspective of 25 years of self-government

Odrodzenie samorządu terytorialnego w 1990 r. stanowiło zasadniczą zmianę ustrojową. Niedawno minęło 25 lat od tego wydarzenia, ale obraz rozwoju samorządności w Polsce trudno jednoznacznie ocenić. Celem niniejszego artykułu jest zarysowanie odpowiedzi na pytanie, w jakim stopniu oczekiwania związane z rewitalizacją społeczności lokalnych poprzez odrodzenie samorządu terytorialnego zostały spełnione, a więc w jakim stopniu realizację znalazła idea pomocniczości. Kwestia ta jest analizowana na przykładzie kilku obszarów życia społecznego: a) aktywności tzw. trzeciego sektora i współpracy organizacji pozarządowych z jednostkami samorządu terytorialnego (pomocniczość pozioma); b) stosowania procedur i technik partycypacji (włączania obywateli do procesu podejmowaniu decyzji publicznych); c) działania jednostek pomocniczych (rad osiedli i sołectw ‒ pomocniczość pionowa); d) aktywności obywatelskiej w postaci ruchów i inicjatyw społecznych (zwłaszcza tzw. ruchów miejskich); e) regionalizmu.Jeśli uznać, że celem reformy samorządowej było praktyczne zrealizowanie idei pomocniczości, to cel ten został osiągnięty. Jednak niewątpliwy sukces polskiej samorządności, który zmienił Polskę na lepsze, nie przełożył się na sukces polskiej samorządności rozumianej jako sfera harmonijnej współpracy wybieralnych władz lokalnych odpowiedzialnych wobec aktywnych społeczności. Struktury samorządu zdominowały życie lokalne, w wielu przypadkach urzędy stanowią największego pracodawcę, co ma negatywne oddziaływanie zarówno w sferze ekonomicznej, jak i społecznej. W tym sensie więc można mówić o częściowej porażce samorządności, która jest dzieckiem sukcesu reformy samorządowej.The revival of local government in 1990 constituted a fundamental change in the Polish political regime. However, on the twenty-fifth anniversary of this event the picture of local government in Poland is still unclear. The article offers answers to questions about how the expectations related to the revitalisation of local communities through the revival of local government have been met and about the scope of the idea of subsidiarity implementation. The following areas of social life are analysed: (i) the activity of what are known as third sector organisations and their cooperation with local government (horizontal subsidiarity); (ii) the use of procedures and techniques of participation by local government; (iii) the functioning of local government auxiliary units (district councils and village councils – vertical subsidiarity); (iv) activities of urban social movementsand initiatives; (v) regionalism. Considering the practical implementation of the idea of subsidiarity as the main purpose of the local government reform, the objective has been achieved. However, the unquestionable success of the Polish self-government which have changed Poland for the better does not entail the revival of Polish local communities. The harmonious  cooperation of elected local authorities accountable to an active community is still missing. Local government structures have dominated local life, being in many places the largest employer, with all negative consequences of this in terms of both economic and social life. In this sense, it can be argued that a partial failure of self-government is a side effect of the success of the self-government reform

Screening for trisomy 21 based on maternal age, nuchal translucency measurement, first trimester biochemistry and quantitative and qualitative assessment of the flow in the DV — the assessment of efficacy

Objectives: The aim of the study was to compare effects of addition of two methods of ductus venosus (DV) flow assessment: qualitative — the assessment of shape of the A-wave (positive or negative), and quantitative — based on the pulsatility index for veins (DVPI) to the basic screening for trisomy 21 at 11 to 13 + 6 weeks of pregnancy. Material and methods: The ultrasound examination was performed in 8230 fetuses in singleton pregnancies at 11– –13 + 6 wks, as a part of a routine screening for chromosomal defects. In DV A-wave was assessed and DVPI was calculated. After the scan blood sample was taken for first trimester biochemistry (BC). Risk for chromosomal defects was calculated and high-risk patients were offered an invasive test for karyotyping. Results: Basic screening with following combination of markers: MA, NT and BC provided lowest detection rate (DR) 87.50% for FPR = 6.94%. After adding qualitative DV A-wave assessment DR increased to 88.75% for FPR = 5.65%. The best DR = 93.75% for FPR = 5.55% was achieved when quantitative DVPI was added. The application of the Receiver Operating Curves curve confirmed validity of the addition of DV flow assessment to the screening model. The highest diagnostic power of the test was achieved when DVPI was added, with the ROC AUC of 0.974. Conclusions: The assessment of DV flow performed at 11–13 + 6 weeks increases DR for trisomy 21 and reduces FPR. The screening model based on the quantitative DV flow analysis (DVPI) gives better results compared to the qualitative flow assessment

Nasal bone in screening for T21 at 11–13 + 6 weeks of gestation — a multicenter study

 Objectives: Trisomy 21 is one of the most common chromosomal defects diagnosed prenatally. Screening for Down syndrome is based on maternal age, measurement of crown-rump length, nuchal translucency and fetal heart rate, together with free β-hCG and PAPP-A at 11 to 13 + 6 weeks. Introduction of additional ultrasound marker of trisomy 21 (evaluation of the nasal bone) may result in increased DR and decreased invasive diagnostic testing rates (FPR).Material and methods: Ultrasound scan with NB evaluation was performed in 5814 fetuses during routine screening for chromosomal defects at 11 to 13 + 6 weeks of gestation. DR and FPR coefficients were calculated for 4 levels of risk as cut-off points for screening model 1, based on MA, NT, and first trimester biochemistry, as well as for screening model 2, based on MA, NT, first trimester biochemistry and NB.Results: There were 5708 normal cases, 71 cases of trisomy 21 and 35 cases of other chromosomal defects. NB was absent in 46 (64.8%) cases and present in 25 (35.3%) cases of trisomy 21, comparing to present NB in 5463 (95.7%) and absent in 245 (4.3%) of normal cases.Conclusions: First-semester screening with additional NB assessment significantly increases the detection rate for trisomy 21 and decreases the rate of false-positive results. Adding NB evaluation at the risk level of 1:50 causes only a small increase in detection rate. Invasive procedures should be performed in that group regardless NB assessment

The Effects of Ethanol Concentration and of Ionic Strength on the Zeta Potential of Titania in the Presence of Sodium Octadecyl Sulfate

Sodium octadecyl sulfate (C18H37SO4Na) induces a negative zeta potential of metal oxides at very low surfactant concentrations as compared with shorter-chained sodium alkyl sulfates. The problem of low solubility of sodium octadecyl sulfate in water was solved by the addition of the surfactant to dispersions as ethanolic stock solution, but then the presence of ethanol in dispersions was inevitable. We demonstrate that the concentration of ethanol (up to 5% by mass) in a dispersion containing titania (TiO2) and sodium octadecyl sulfate has an insignificant effect on the zeta potential of particles. We further demonstrate that the shifts in the IEP of titania induced by the presence of sodium octadecyl sulfate are independent of the NaCl concentration. The results obtained in this study can be generalized for 1-1 salts other than NaCl, for metal oxides other than titania, for organic co-solvents other than ethanol, and for sparingly soluble ionic surfactants other than sodium octadecyl sulfate

Electric Double Layer in Water-Organic Mixed Solvents: Titania in 50% Ethylene Glycol

Ethylene glycol (EG) and its mixtures with water are popular components of nanofluids used as heat transfer fluids. The stability of nanofluids against coagulation is correlated with their zeta potential. The electrophoretic mobility of titania nanoparticles in 50-50 w/w EG was studied as a function of the concentration of various solutes. HCl, NaOH, SDS and CTMABr at concentrations up to 0.01 M are strong electrolytes in 50% EG, that is, the conductance of their solutions is proportional to the concentration. HCl, NaOH and CTMABr were very efficient in inducing a high zeta potential for titania in 50% EG. NaOH induced a negative zeta potential in excess of 70 mV, and HCl and CTMABr induced a positive zeta potential in excess of 70 mV at concentrations below 10−4 M. Apparently, HCl, NaOH and CTMABr are also more efficient than SDS in terms of nanofluid stabilization against coagulation. An overdose of base (>1 mM) results in depression of the negative zeta potential. This result may be due to the specific adsorption of sodium on titania from 50% EG

Synthesis and Properties of SBA-15 Modified with Non-Noble Metals

Modification of SBA-15 with non-noble metal leads to functional materials, which can be applied as gas sensors, adsorbents, and catalysts of various reactions. The new materials contain up to four various metals, which are deposited consecutively or simultaneously at various concentrations ranging from a fraction of 1% to an amount that is comparable with the mass of silica-support. These materials contain metals at various oxidation levels, usually as oxides, which occur in crystalline form (a typical crystallite size of about 10 nm matches the width of the SBA-15 channels), but in a few other materials, crystalline metal compounds have not been detected. Many researchers have provided detailed physico- chemical characteristics of SBA-15 modified with non-noble metals by the means of various microscopic and spectroscopic techniques

Dispersions of Metal Oxides in the Presence of Anionic Surfactants

We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it