Surface chemistry of metal oxide nanoparticles: NMR and TGA quantification.

Surface functionalization is widely used to control the behavior of nanomaterials for a range of applications. However, methods to accurately quantify surface functional groups and coatings are not yet routinely applied to nanomaterial characterization. We have employed a combination of quantitative NMR (qNMR) and thermogravimetric analysis (TGA) to address this problem for commercial cerium, nickel, and iron oxide nanoparticles (NPs) that have been modified to add functional coatings with (3-aminopropyl)triethoxysilane (APTES), stearic acid, and polyvinylpyrrolidone (PVP). The qNMR method involves quantification of material that is released from the NPs and quantified in the supernatant after removal of NPs. Removal of aminopropylsilanes was accomplished by basic hydrolysis whereas PVP and stearic acid were removed by ligand exchange using sodium hexametaphosphate and pentadecafluorooctanoic acid, respectively. The method accuracy was confirmed by analysis of NPs with a known content of surface groups. Complementary TGA studies were carried out in both air and argon atmosphere with FT-IR of evolved gases in argon to confirm the identity of the functional groups. TGA measurements for some unfunctionalized samples show mass loss due to unidentified components which makes quantification of functional groups in surface-modified samples less reliable. XPS provides information on the presence of surface contaminants and the level of surface hydroxylation for selected samples. Despite the issues associated with accurate quantification using TGA, the TGA estimates agree reasonably well with the qNMR data for samples with high surface loading. This study highlights the issues in analysis of commercial nanomaterials and is an advance towards the development of generally applicable methods for quantifying surface functional groups.

An exploratory study of the effect of labor pain management on postpartum depression among Chinese women.

OBJECTIVES: The purpose of this study was to investigate the effects of pain relief during labor on the occurrence of potential postpartum depression in early postpartum among Chinese women. MATERIAL AND METHODS: A quasi-experimental study used, with a convenience sample of 565 women who delivered at the Women's Hospital, School of Medicine. Three types of pain relief were administered based on the women's preference (doula, n = 301; transcutaneous electrical nerve stimulation, n = 51; epidural analgesia, n = 213). Pain scores of participants were assessed using a 10-point visual analog scale during labor. The Edinburgh Postnatal Depression Scale was administered in person and by phone at three days and two to four weeks after delivery, respectively. All data were analyzed using SPSS 20.0. RESULTS: Visual analog scale pain scores in the epidural analgesia group decreased significantly during labor compared to those of the other two groups. The occurrence of potential postpartum depression at three days was 6.6% in the epidural analgesia group, 1.3% in the doula group, and 2% in the transcutaneous electrical nerve stimulation group (P = 0.04). Furthermore, potential postpartum depression occurred at two to four weeks after childbirth in 16% (34/213) of the participants in the epidural analgesia group, 7.3% (22/301) of those who received doula support, and in 7.8% (4/51) of those in the transcutaneous electrical nerve stimulation group (P = 0.006). CONCLUSIONS: The results indicated that epidural analgesia was an effective pain relief method during labor. However, it did not reduce the occurrence of potential postpartum depression and was associated with higher postnatal depression scores.

The Knee Arthroplasty Trial (KAT) design features, baseline characteristics, and two-year functional outcomes after alternative approaches to knee replacement.

BACKGROUND: The aim of continued development of total knee replacement systems has been the further improvement of the quality of life and increasing the duration of prosthetic survival. Our goal was to evaluate the effects of several design features, including metal backing of the tibial component, patellar resurfacing, and a mobile bearing between the tibial and femoral components, on the function and survival of the implant. METHODS: A pragmatic, multicenter, randomized, controlled trial involving 116 surgeons in thirty-four centers in the United Kingdom was performed; 2352 participants were randomly allocated to be treated with or without a metal backing of the tibial component (409), with or without patellar resurfacing (1715), and/or with or without a mobile bearing (539). Randomization to more than one comparison was allowed. The primary outcome measures were the Oxford Knee Score (OKS), Short Form-12, EuroQol-5D, and the need for additional surgery. The results up to two years postoperatively are reported. RESULTS: Functional status and quality-of-life scores were low at baseline but improved markedly across all trial groups following knee replacement (mean overall OKS, 17.98 points at baseline and 34.82 points at two years). Most of the change was observed at three months after the surgery. Six percent of the patients had additional knee surgery within two years. There was no evidence of differences in clinical, functional, or quality-of-life measures between the randomized groups at two years. CONCLUSIONS: Patients have substantial improvement following total knee replacement. This is the first adequately powered randomized controlled trial, of which we are aware, in which the effects of metal backing, patellar resurfacing, and a mobile bearing were investigated. We found no evidence of an effect of these variants on the rate of early complications or on functional recovery up to two years after total knee replacement.

Ganglioside partitioning and aggregation in phase-separated monolayers characterized by bodipy GM1 monomer/dimer emission.

The distribution of Bodipy GM1 in monolayers of binary and ternary lipid mixtures with coexisting fluid and ordered phases has been examined using a combination of atomic force microscopy and near-field scanning optical microscopy. Monolayers deposited at high (30 mN/m) and low (5 or 10 mN/m) surface pressures were examined and compared to those containing the same concentration of unlabeled ganglioside. Measurements of monomer and dimer Bodipy emission were used to distinguish aggregated from dilute ganglioside levels. For binary DPPC/DOPC monolayers, Bodipy GM1 is distributed throughout both the fluid and ordered phases at low surface pressures, and both labeled and unlabeled gangliosides result in a reduction in the size of ordered DPPC domains at 0.4% and the appearance of small aligned ganglioside-rich domains at 4%. In agreement with earlier studies, GM1 is heterogeneously distributed in small islands in the condensed DPPC domains at high surface pressure. By contrast, Bodipy GM1 causes the disappearance of large DPPC domains at 0.4% and the formation of a new GM1-rich phase at 4%. The addition of both gangliosides leads to a comparable loss of large ordered domains at low surface pressure and the appearance of a new GM1-rich phase at 30 mN/m for ternary lipid mixtures containing cholesterol. The results demonstrate the complexity of GM1 partitioning and illustrate the utility of complementary AFM and high spatial resolution two-color fluorescence experiments for understanding Bodipy GM1 aggregation and distribution.

Pain assessment and procedural pain management practices in neonatal units in Australia.

OBJECTIVE: To identify current pain assessment and procedural pain management practices in neonatal units in Australia. METHODS: Postal survey conducted during December 2003 and January 2004. The survey comprised questions relating to pain assessment scores, pain reduction strategies for minor painful procedures and the use of articulated policies relating to procedural pain management. Participants were the Nurse Unit Managers or their nominees of neonatal intensive care units, special care units and newborn emergency transport services in Australia. RESULTS: Surveys were sent to 181 eligible organizations, and 105 of these were returned (58%). Six units (6%) used pain assessment scores on a regular basis, and 16 units (15%) had an articulated policy directing pain management practices during painful procedures. Non-nutritive sucking and various nursing comfort measures were the pain reduction strategies most frequently used during minor painful procedures. Twenty-four units (23%) used sucrose or other sweet-tasting solutions during procedures; however, the reported frequency of their usage was low. Breast-feeding during venepuncture, heel lance and intramuscular or subcutaneous injection was infrequently practised and topical anaesthetic agents were rarely used. CONCLUSION: This survey demonstrates that the majority of Australian neonatal units have no articulated policy to guide pain management during painful procedures and do not regularly undertake pain assessments. Current evidence-based strategies to reduce procedural pain in hospitalized infants are used infrequently.