Facile two-step preparation of polystyrene/anatase TiO2 core/shell colloidal particles and their potential use as an oxidation photocatalyst

Titania and materials containing titania have received considerable attention due to their technological importance in many areas. In this study, anatase crystalline titania (TiO₂) coated polystyrene (PS) colloidal particles were successfully prepared in two easy steps. First, a one pot synthesis of the colloidal particles was produced via an emulsifier-free emulsion copolymerization of styrene (S) and 2-(dimethylamino)ethyl methacrylate (DMA) at pH 4.0. In the second step, the synthesized particles were coated by titania using a sol–gel process in-situ hydrolysis and a condensation reaction of titanium(IV) isopropoxide in an acidic aqueous solution. In this way, anatase crystalline titania, rather than the usual amorphous form, was obtained as a shell on the PS colloidal particles. Both the PS colloidal particles and the polystyrene/anatase titania (PS/TiO₂) core/shell colloidal particles had monodisperse morphology and were characterized using SEM, Zetasizer, FTIR, XRD and TGA techniques or measurements. In addition, the photocatalytic activity of the PS/TiO₂ core/shell particles was tested for the first time in an oxidation reaction, in the oxidation of 4-methoxybenzyl alcohol (MBA) with O₂ in water. Much higher selectivities of the target product, p-anisaldehyde (AA), were obtained with the PS/TiO₂ core/shell particles than with a commercial anatase crystalline TiO₂.     

A minimally painful,comfortable, and safe technique for hemodialysis catheter placement in children: Superficial cervical plexus block

The superficial cervical plexus block (SCPB) is utilized in pediatric patients to perform certain surgical procedures, but there is no evidence supporting its use in hemodialysis catheter placement. We evaluated the analgesic effectiveness, intraoperative complications, and patient satisfaction associated with SCPB for pediatric patients in renal failure undergoing emergent dialysis catheterization. A total of 52 patients ranging from 1 to 17 years old that required emergent dialysis catheter placement and received SCPB were included in this study. During the catheterization, intraoperative pain scores, requirement for additional analgesia, catheterization access site, and intraoperative complications were recorded. The Children's Hospital of Eastern Ontario Pain Scale (mCHEOPS) was used to determine pain ratings during skin puncture with the needle, skin dilatation, and securing the catheter with stitches. The patients had an average age of 8.46 ± 5.3 years. The preferred catheterization entry site was through right internal jugular vein, which was achieved in 80.7% of patients. However, 19.3% of patients required access through the right subclavian vein. The average mCHEOPS score during skin puncture was 1.4 ± 0.5, and the mean mCHEOPS score was 2.3 ± 0.6 for skin dilatation. Finally, the average mCHEOPS score while securing the catheter with stitches was 1.3 ± 0.4. No patient required fentanyl for additional analgesia. No intraoperative complications occurred. The benefits gained from using SCPB performed by an experienced anesthesiologist for hemodialysis catheter placement include providing sufficient analgesia and optimal surgical conditions while avoiding the complications associated with general anesthesia for pediatric patients with renal failure.     

Characterization of multiple-antibiotic-resistant Salmonella typhimurium stains: molecular epidemiology of PER-1-producing isolates and evidence for nosocomial plasmid exchange by a clone

We characterized epidemiologic and genetic features of nosocomially originated multiple-antibiotic-resistant Salmonella typhimurium isolates from two hospitals. A total of 32 multiply resistant strains, isolated during a 28-month period, were studied. Four resistance phenotypes were distinguished on the basis of the results of disc diffusion tests. Group 1 was resistant to chloramphenicol, gentamicin, tobramycin, amikacin, and the newer cephalosporins because of the production of an extended-spectrum beta-lactamase (PER-1). Group 2 exhibited the same pattern plus resistance to sulfamethoxazole-trimethoprim (Sxt). Except for Sxt resistance, dominant phenotypes of both groups were transferred on an identical plasmid, pSTI1 (81 MDa). Group 3 was resistant to ampicillin, chloramphenicol, gentamicin, tobramycin, and Sxt. This pattern was also transferred on an 81-MDa plasmid (pSTI2) which differed from pSTI1 on the basis of EcoRI and HindIII restriction fragments. Group 4 was resistant to ampicillin, chloramphenicol, and tetracycline, and a 74-MDa nonconjugative plasmid was detected. Restriction fragment length polymorphism of RNA-encoding DNA and arbitrarily primed PCR tests revealed that bacteria from groups 1, 2, and 3 were clonally related. Epidemiologic data also supported the clonal-dissemination hypothesis. We concluded that S. typhimurium isolates acquire and exchange multiple-resistance plasmids in hospital microflora.     

Characterization of activated carbon produced from almond shell and hazelnut shell

Ammonium chloride-impregnated and untreated almond shell and hazelnut shell samples were carbonized in a flow of nitrogen at relatively low temperatures. Pore structure characterization and sorption capacities of activated carbons prepared from shells of almond and hazelnut indicated that treatment with NH₄Cl increased the total surface area and improved sorption characteristics. Chemical activation carried out at 350°C gave products with surface area values above 500 m² g^?1. On the other hand, the surface area values observed for the products obtained from untreated raw materials were about half of this value. The surface area of products obtained from NH₄Cl-impregnated samples reached values of over 700 m² g^?1 when the carbonization temperature was increased 700°C.     

The influence of poly(styrene sulfonate) addition to cellulosic fibers by wet processing on the physicomechanical properties of paper

The study of the effect of sodium poly(styrene sulfonate) addition to suspensions of fibers, in the presence of aluminum salts as adsorption aids, revealed the retention effect of fine solids during sheet formation. Polyelectrolyte adsorption also causes an increase of bounding energy in the web. It is shown that the improvement observed for the dry strength properties of paper is a consequence of these two effects. (In this paper the words “fine solids” or “fines” indicate the parts of the cellulosic material which filtrates through a 150-mesh screen, regardless of its nature.)     

Association of anxiety,sleepiness, and sexual dysfunction with restless legs syndrome in hemodialysis patients

Restless legs syndrome (RLS) is characterized by unpleasant sensations, pain in the legs along with irresistible urges to move the legs when at rest. It is often accompanied by sleep disturbance. The purpose of this study was to assess the association of anxiety and sleepiness with sexual function in hemodialysis patients with and without RLS. Sociodemographic parameters, laboratory data of hemodialysis patients from three dialysis centers were collected prospectively. Anxiety, sleepiness, sexual function, and presence of RLS symptoms were assessed with standardized questionnaires as the RLS Diagnosis and Scale, Hamilton Anxiety Rating Scale, Epworth Sleepiness Scale (ESS), Arizona Sex Experiences Scale (ASEX). Univariate, regression tree method were used for statistical analysis. RLS was observed in 45.9% (n = 113) of hemodialysis patients (n = 246). The mean age of patients and duration of hemodialysis were 59.7 ± 14.0 and 4.9 ± 4.2 years, respectively. The correlation between Arizona Sexual Experiences Scale (ASEX) and sociodemographic features was significant (P < 0.0001). Patients with RLS had higher scores for anxiety (9.4 ± 7.8 with RLS and 6.8 ± 6.0 without), higher ESS (ESS, 6.6 ± 5.2 with RLS and 4.6 ± 4.0 without), and higher ASEX (24.6 ± 5.7 with RLS and 22.5 ± 6.8 without) than did those without RLS. The presence of RLS symptoms in hemodialysis patients was associated with sleepiness, anxiety, and sexual dysfunction. A regression tree method, which is a different statistical method, can help physicians estimate patients ASEX, RLS, ESS, and anxiety scores.     

The synthesis and sodium-silver ion exchange of sodalites

Aluminosilicate sodalites of three different types--chlorosodalite, basic sodalite, and oxalate sodalite--have been synthesized in their sodium forms using hydrothermal synthesis. The syntheses were investigated in terms of their relative rates of crystallization and final crystallinities using powder X-ray diffraction. These sodalites were subsequently loaded with silver by aqueous ion exchange. The exchange was studied primarily by monitoring the solution phase. Rate of exchange and equilibrium behavior have been established over the temperature range of 25-80°C for all three types. Extreme selectivity toward silver over sodium was observed, with little dependence on temperature. Both sodium and silver sodalites were characterized by powder diffraction, and crystallographic data for silver sodalites have been derived using Rietveld refinement. Electron micrographs of sodalites have been used for investigations of crystallite morphology and size. Silver sodalites have been observed to manifest various optical properties including photochromic, barochromic, thermochromic, and fluorescent behavior.     

An improved lumped element nonlinear circuit model for a circular CMUT cell

This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell. The force model is rederived so that the energy and power is preserved in the equivalent circuit model. The model is able to predict the entire behavior of CMUT until the membrane touches the substrate. Many intrinsic properties of the CMUT cell, such as the collapse condition, collapse voltage, the voltage-displacement interrelation and the force equilibrium before and after collapse voltage in the presence of external static force, are obtained as a direct consequence of the model. The small signal equivalent circuit for any bias condition is obtained from the large signal model. The model can be implemented in circuit simulation tools and model predictions are in excellent agreement with finite element method simulations.