Structure and dynamics of titania - poly(N-vinyl caprolactam) composite hydrogels.

The morphologies and dynamics of poly(N-vinyl caprolactam) (PVCL) based hydrogels with titania nanoparticles in different states (native, air-dried to a constant weight and swollen in H2O or D2O) are studied by a combination of complementary techniques: wide angle X-ray scattering, small angle neutron scattering, neutron spin echo spectroscopy, differential scanning calorimetry. The results suggest the presence of different structural types of water leading to different properties of the hydrogels. We propose a hierarchical structure of hydrogels spanning from the molecular to the microscopic scale consistent with both the static structure (polymer mesh size, association of the nodes of crosslinks and microchains of PVCL) and the dynamics (rate of relaxation of polymer chains, hydrodynamic polymer-polymer correlation length). The presence of nanoscale titania does not change the molecular structure and nanostructure due to its aggregation into meso-domains, but does affect the microstructure, changing the response rate to a temperature jump from 20 to 50 °C. Titania nanoparticles do not change the equilibrium swelling degree of hydrogels.

Structural Characterization of Pluronic Micelles Swollen with Perfume Molecules.

The insertion in nonionic polymer micelles (Pluronics F127) of seven essential oils and some of the pure compounds that compose them was investigated by complementary differential scanning calorimetry, small-angle X-ray, and neutron scattering (SAXS and SANS). The study revealed various insertion and swelling behaviors for the different oil molecules, an evidence of different interaction mechanisms involved between oils and Pluronic monomers. Thermodynamically, the addition of oil increased the micellization enthalpy due to an enhanced release of water molecules, leading subsequently to a decrease of the critical micellar temperature (CMT). Structurally, with oil, SANS revealed the presence of large aggregates at lower temperature than the CMT for which their size is maximal. Above the CMT, the size decreased and the equilibrium was reached a few degrees after the temperature corresponding to the maximum of the endothermic peak. At 37 °C, the detailed combined SANS and SAXS analysis demonstrated a partial phase separation between the oil and the poly(propylene oxide) core. The hydrophilic stabilizing poly(ethylene oxide) shell remains unchanged.

Porosity of silica Stöber particles determined by spin-echo small angle neutron scattering.

Stöber silica particles are used in a diverse range of applications. Despite their widespread industrial and scientific uses, information on the internal structure of the particles is non-trivial to obtain and is not often reported. In this work we have used spin-echo small angle neutron scattering (SESANS) in conjunction with ultra small angle X-ray scattering (USAXS) and pycnometry to study an aqueous dispersion of Stöber particles. Our results are in agreement with models which propose that Stöber particles have a porous core, with a significant fraction of the pores inaccessible to solvent. For samples prepared from the same master sample in a range of H2O : D2O ratio solutions we were able to model the SESANS results for the solution series assuming monodisperse, smooth surfaced spheres of radius 83 nm with an internal open pore volume fraction of 32% and a closed pore fraction of 10%. Our results are consistent with USAXS measurements. The protocol developed and discussed here shows that the SESANS technique is a powerful way to investigate particles much larger than those studied using conventional small angle scattering methods.

Influence of additives on the structure of surfactant-free microemulsions.

We study the addition of electrolytes to surfactant-free microemulsions in the domain where polydisperse pre-Ouzo aggregates are present. As in previous studies, the microemulsion is the ternary system water/ethanol/1-octanol, where ethanol acts as co-solvent. Addition of electrolytes modifies the static X-ray and neutron scattering, and dynamic light scattering patterns, as well as the position of the miscibility gap, where spontaneous emulsification occurs upon dilution with water. All observations can be rationalized considering that electrolytes are either "salting out" the ethanol, which is the main component of the interface stabilizing the aggregates, or producing charge separation via the antagonistic ion effect discovered by Onuki et al. Amphiphilic electrolytes, such as sodium dodecylsulfate or sodium dietheylhexylphosphate, induce a gradual transition towards monodisperse ionic micelles with their characteristic broad scattering "peak". In these micelles the ethanol plays then the role of a cosurfactant. Dynamic light scattering can only be understood by combination of fluctuations of aggregate concentration due to the vicinity of a critical point and in-out fluctuations of ethanol.

Improvement of estradiol esters monitoring in bovine hair by dansylation and liquid chromatography/tandem mass spectrometry analysis in multiple reaction monitoring and precursor ion scan modes.

RATIONALE: The control of forbidden anabolic practices in cattle in the European Union has become challenging since endogenous compounds such as estradiol derivatives can potentially be used as growth promoters. Due to the great difficulty in establishing a reference threshold value for endogenous steroids, the direct detection of steroid esters in hair is an efficient strategy for the detection of 'natural' steroid abuse in cattle. METHODS: The present study aimed to develop and validate according to the current European standards a specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) analytical strategy to monitor estrogen esters in bovine hair. The analysis was performed by positive ion electrospray ionisation (ESI+) after dansylation. Two acquisition modes were then assessed: single reaction monitoring and precursor ion scanning. RESULTS: The results showed that the introduction of a dansylation step strongly improves the sensitivity of the detection of estradiol-17-esters by LC/(ESI+)-MS/MS. The CCα values are in the range 1-10 ng g(-1) after optimisation, except for estradiol decanoate for which the derivatisation is not efficient. In addition, this LC/MS/MS approach makes it possible to carry out a precursor ion scan to screen for the presence of these estradiol 17-esters in hair samples. CONCLUSIONS: Based on the specific product ions, i.e. m/z 255 in native conditions or m/z 171 after dansylation, this strategy has the advantage of detecting any (un)known estradiol ester and of giving access to the [M + H](+) ion of the suspected ester through only a single analysis.

Hydration and interactions in protein solutions containing concentrated electrolytes studied by small-angle scattering.

During protein crystallization and purification, proteins are commonly found in concentrated salt solutions. The exact interplay of the hydration shell, the salt ions, and protein-protein interactions under these conditions is far from being understood on a fundamental level, despite the obvious practical relevance. We have studied a model globular protein (bovine serum albumin, BSA) in concentrated salt solutions by small-angle neutron scattering (SANS). The data are also compared to previous studies using SAXS. The SANS results for dilute protein solutions give an averaged volume of BSA of 91,700 Å(3), which is about 37% smaller than that determined by SAXS. The difference in volume corresponds to the contribution of a hydration shell with a hydration level of 0.30 g g(-1) protein. The forward intensity I(0) determined from Guinier analysis is used to determine the second virial coefficient, A(2), which describes the overall protein interactions in solution. It is found that A(2) follows the reverse order of the Hofmeister series, i.e. (NH(4))(2)SO(4) < Na(2)SO(4) < NaOAc < NaCl < NaNO(3) < NaSCN. The dimensionless second virial coefficient B(2), corrected for the particle volume and molecular weight, has been calculated using different approaches, and shows that B(2) with corrections for hydration and the non-spherical shape of the protein describes the interactions better than those determined from the bare protein. SANS data are further analyzed in the full q-range using liquid theoretical approaches, which gives results consistent with the A(2) analysis and the experimental structure factor.

[Information tool about labor and delivery designed by Delphi method]. / Élaboration d'un outil d'information sur l'accouchement : consensus par la méthode Delphi.

OBJECTIVE: The integration of couples in decision making in obstetrics is necessary to improve the experience of giving birth. The objective of this work is to elaborate a new tool to provide information to health professionals. METHODS: A 5-round Delphi method was used to define the information points. The 20 multi-disciplinary experts answered 5 surveys on the information to deliver concerning childbirth. The selected items were organized with mind mapping. RESULTS: 54 items were identified on the first round. 5 were retained after the second survey while the rest were reformulated and submitted for the third round. Amongst the 47 items submitted, 19 were retained, the rest were removed, merged or reworded. The fourth survey included 22 items of which 11 were retained. The fifth survey concerned the 11 remaining items and 2 new ones. During this round, 7 items were retained. This round made it possible to reach the consensus. In total, 42 items reached the consensus of the experts. They were then split into 5 mind maps allowing their visual organization to form the information tool. CONCLUSION: The tool elaborated in a multi-disciplinary manner offers complementary information to that already given during childbirth preparation courses. It is a framework for the information to be given that leaves the content up to each professional.

PCR detection of thermophilic spore-forming bacteria involved in canned food spoilage.

Thermophilic bacteria that form highly heat-resistant spores constitute an important group of spoilage bacteria of low-acid canned food. A PCR assay was developed in order to rapidly trace these bacteria. Three PCR primer pairs were designed from rRNA gene sequences. These primers were evaluated for the specificity and the sensitivity of detection. Two primer pairs allowed detection at the species level of Geobacillus stearothermophilus and Moorella thermoacetica/thermoautrophica. The other pair allowed group-specific detection of anaerobic thermophilic bacteria of the genera Thermoanaerobacterium, Thermoanaerobacter, Caldanerobium and Caldanaerobacter. After a single enrichment step, these PCR assays allowed the detection of 28 thermophiles from 34 cans of spoiled low-acid food. In addition, 13 ingredients were screened for the presence of these bacteria. This PCR assay serves as a detection method for strains able to spoil low-acid canned food treated at 55°C. It will lead to better reactivity in the canning industry. Raw materials and ingredients might be qualified not only for quantitative spore contamination, but also for qualitative contamination by highly heat-resistant spores.

Aqueous laponite clay dispersions in the presence of poly(ethylene oxide) or poly(propylene oxide) oligomers and their triblock copolymers.

The effect of polyethylene oxide (PEO) or polypropylene oxide (PPO) oligomers of various molecular weight (Mw) as well as of triblock copolymers, based on PEO and PPO blocks, on aqueous laponite RD suspensions was studied with small-angle neutron scattering (SANS). The radius of gyration (RG) increases for low M w whereas the opposite occurs for larger Mw. This behavior is explained on the basis that an effective R G is given by two contributions: (1) the size of the particles coated with the polymer and (2) the interactions between the laponite RD particles which are attractive for small and repulsive for large polymers. The SANS curves in the whole Q-range are well described by a model of noninteracting polydisperse core+shell disks, where the thickness of the polymer layer increases with the Mw. The adsorbed polymer is in a more compact conformation compared to a random coil distribution while the fraction of the polymer in the shell formed around the laponite RD particles is nearly independent of Mw. For increasing laponite RD amounts, at a given polymer composition, the thickness of the polymer slightly changes. In some cases, where also gelation is sped up, a structure factor with attractive interaction was employed which allowed to evaluate the attractive forces between the laponite RD particles. The gelation time was determined for mixtures at fixed copolymer and laponite RD concentrations. Surprisingly, it is observed that gels are formed despite the fact that the binding sites of the laponite RD particles are almost covered but the polymer size is too small to prevent aggregation. The gelation rate is correlated to structure and thermodynamics of these systems. Namely, when the balance between the steric forces and the depletion attractive forces undergoes an abrupt change the gelation time also undergoes a sharp variation. For lower and comparable Mw, PPO speeds up the gelation more efficiently than PEO while for higher Mw the gelation kinetics is slowed down again. Interestingly, copolymers of PEO and PPO blocks do not induce gelation in the time-window where the homopolymers do.

Aqueous block copolymer-surfactant mixtures and their ability in solubilizing chlorinated organic compounds. A thermodynamic and SANS study.

Within the topic of surfactant enhanced solubilization of additives sparingly soluble in water, volumetric, solubility, conductivity, and small-angle neutron scattering (SANS) experiments on mixtures composed of alpha,omega-dichloroalkane, surfactant, copolymer, and water were carried out at 298 K. The triblock copolymers (ethylene oxide)132(propylene oxide)50(ethylene oxide)132 (F108) and (ethylene oxide)76(propylene oxide)29(ethylene oxide)76 (F68) were chosen to investigate the role of the molecular weight keeping constant the hydrophilic/hydrophobic ratio. The selected surfactants are sodium decanoate (NaDec) and decyltrimethylammonium bromide (DeTAB) with comparable hydrophobicity and different charged heads. The alpha,omega-dichloroalkanes were chosen as contaminant prototypes. For the water + surfactant + copolymer mixtures, both the volume and the SANS results straightforwardly evidenced that (1) monomers of NaDec and copolymer unimers generate small mixed aggregates, (2) monomers of DeTAB combined with copolymer unimers do not form aggregates, and (3) unimeric copolymer is solubilized into NaDec and DeTAB micelles. The alpha,omeaga-dichloroalkanes presence induces the F108 aggregation even at very low copolymer composition. The addition of surfactant disintegrates the F108 aggregates and, consequently, the additive is expelled into the aqueous phase. Once F108 is in the unimeric state, it forms copolymer-micelle aggregates which incorporate the oil. In the case of F68 both the volumetric and the SANS data reveal that the additive does not alter the copolymer unimeric state. Moreover, they show that for the aqueous DeTAB-F68 system the additive trapping in both the copolymer-micelle aggregate and the pure micelles takes place being enhanced in the former aggregate in agreement with solubility experiments. For the NaDec-F68 mixtures, an additional solubilization process in the premicellar copolymer-surfactant microstructures occurs. SANS and conductivity data show that the additive incorporation into the mixed and the pure micelles does not essentially influence the structural properties of the aggregates.

Application of stable carbon isotope analysis to the detection of 17beta-estradiol administration to cattle.

The use of anabolic agents in food producing animals is prohibited within the EU since 1988 (96/22/EC directive). The control of the illegal use of natural steroid hormones in cattle is still an exciting analytical challenge as far as no definitive method and non-ambiguous analytical criteria are available. The ability of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to demonstrate the administration of 17beta-estradiol to bovine has been investigated in this paper. By comparison of 13C/12C isotopic ratio of main urinary estradiol metabolite, i.e. 17alpha-estradiol, with two endogenous reference compounds (ERCs), i.e. dehydroepiandrosterone (DHEA) and 5-androstene-3beta,17alpha-diol, the differentiation of estradiol metabolite origin, either endogenous or exogenous, has been proved to be achievable. After treatment, the delta(13)C(VPDB)-values of 17alpha-estradiol reached -27 per thousand to -29 per thousand, whereas delta13CVPDB-values of DHEA remained between -13 per thousand and -20 per thousand depending on the diet, maize and grass, respectively. A significant difference of delta13CVPDB between ERCs and 17alpha-estradiol was measurable over a period of 2 weeks after estradiol ester administration to the animal.

The relationship of the 6-min walk test to maximal oxygen consumption in transplant candidates with end-stage lung disease.

STUDY OBJECTIVE: To assess the relationship of distance ambulated during the 6-min walk test (6'WT) to maximal oxygen consumption (VO2 max). DESIGN: Multivariate analysis of patient characteristics to VO2 max. SETTING: Pre-lung transplant evaluation. PATIENTS: 60 patients (22 men, 38 women; mean age, 44 years) with end-stage lung disease (mean FEV1 and forced vital capacity of 0.97 and 1.93, respectively). MEASUREMENTS AND RESULTS: The 6'WT was performed on a level hallway surface, and VO2 max was obtained during maximal cycle ergometry exercise testing with respiratory gas analysis. Multivariate analysis of patient characteristics (age, sex, weight, FEV1, FVC, diffusing capacity for carbon monoxide (DCO), 6'WT distance ambulated, number of rests per 6'WT, and the maximal heart rate, blood pressure, rate-pressure product, respiratory rate, oxygen saturation, rating of perceived exertion, and amount of supplemental oxygen used during the 6'WT) was performed on two groups of 30 patients each (group A or B) who were randomly assigned to either group by a process of random selection using a computer-generated random numbers program. Distance ambulated was the strongest independent predictor of VO2 max (r = 0.73; p < 0.0001) in both groups, and adding age, weight, and pulmonary function test results (FVC, FEV1, and DCO) to the regression equation increased the correlation coefficient to 0.83. Because of the significant correlation of distance ambulated during the 6'WT to VO2 max, the prediction equation obtained from the multivariate analysis of group A, VO2 max = 0.006 x distance (feet) +3.38, was used to estimate the VO2 max of the group B patients. No significant difference was observed between the estimated (x +/- SD = 8.9 +/- 2.4 mL/kg/min) and observed (x +/- SD = 9.4 +/- 3.8 mL/kg/min) VO2 max (mean difference, 0.5 mL/kg/min; SD of the difference = 2.88). CONCLUSIONS: The distance ambulated during a 6'WT can predict VO2 max in patients with end-stage lung disease. The addition of several patient characteristics can increase the ability to predict VO2 max and account for more of the variability. Such information is valuable when assessing patient response to therapeutic intervention if respiratory gas analysis is unavailable or impractical.

Reviews and summaries of research related to AACN 1980 research priorities: clinical topics.

This article reviews and summarizes the research conducted following publication of the 1980s American Association of Critical-Care Nurses' clinical research priorities. Original research conducted on the clinical priority topics between 1981 and 1991 was included. Review articles, doctoral dissertations, theses and abstracts were excluded unless judged to provide important information on the topic. Following the statement of each priority, progress in the area is summarized. Limitations and measurement issues are discussed as appropriate. Recommendations for future research are provided, and progress in the area is summarized.

Determining AACN's research priorities for the 90s.

The American Association of Critical-Care Nurses completed a three-phased process of priority identification for critical care nursing research. In phase 1, a 78-item survey was generated following a comprehensive review of potential research topics. In phase 2, approximately 1000 critical care nurses rated each item on the survey for importance to critical care nursing. Based on these results, the AACN Research Committee formulated a clinical and a nonclinical (contextual) list of research topics. Each list contained 25 topics. In phase 3, topics were given final rankings at a 1-day Consensus Conference on Research Priorities. Both Likert-type and magnitude estimation scaling were used to determine priority ranking of items on each list. As a result, both clinical and contextual research priorities were established for AACN.

Reviews and summaries of research related to AACN 1980 research priorities: contextual topics.

This article reviews and summarizes the research conducted following publication of the 1980s American Association of Critical-Care Nurses' contextual research priorities. Reports of original research conducted on the contextual priority topics between 1981 and 1991 were included. Review articles, doctoral dissertations, theses, and abstracts were excluded unless judged to provide important information on the topic. Following the statement of each priority, progress in the area is summarized. Limitations and measurement issues are discussed as appropriate. Recommendations for future research are provided, and progress in the area is summarized.

Infection control practices in cardiac transplant recipients. The Research Committee, Houston-Gulf Coast Chapter of the American Association of Critical-Care Nurses.

Infection is a common cause of morbidity and mortality among transplant recipients. Infection control measures lie within the realm of nursing interventions and involve large expenditures of resources. Because transplantation is such a new specialty, few standards exist. The research question for this study was What nursing interventions are being used to prevent infection in cardiac transplant recipients? A 156-item questionnaire was developed that included isolation procedures, dressings, invasive lines, medications, staffing, staff education, dress codes, unit design, visitation, infections, length of stay, survival, and other demographic data. Content validity was established by a panel of transplant experts. After local piloting, the tool was mailed to 120 cardiac transplant centers, and 68 were returned completed. Data were analyzed using descriptive and correlational statistics. Findings revealed wide diversity in practice. Older and larger transplant programs tended to use fewer precautions. Survival rates appeared unrelated to the number of precautions used.

Stress ulceration in the critically ill patient.

Even though considerable progress has been made in prophylaxis and treatment, the problem of stress ulceration continues to pose a serious threat to many critically ill patients. Intensive nursing assessments and interventions can dramatically affect outcomes for these patients. Critical care nurses must identify high-risk patients, carefully monitor their course, and collaborate with physicians, pharmacists, and other members of the health care team to select optimal therapies.

Experiences of a nursing ethics forum. Case studies and outcomes.

Nursing staff members should need few rules and should focus on using critical thinking to guide nursing practice and care. Nurses are decision makers participating in collaborative practice. A high degree of professionalism, responsibility, and accountability is expected. We feel that this program has succeeded not only in meeting the mission and vision of the department of nursing but also that of the hospital. It also has developed to promote the philosophy that nurses must be committed to providing excellence in patient care. In addition to developing this group concept as a model, our intention is to assist staff members with the continued expansion of the group and its tenets. As Uustal asserted, the knowledge of ethical theories and principles can stimulate the nurse's thinking, and ethical decision making can offer direction; however, only you can make ethical decisions. We hope to continue the development of clinical, ethical decision-making skills and to promote the value of this program to the ongoing growth and development of professionalism in nursing.

A focused strategic plan for outcomes evaluation.

This article describes how organizations devise strategic directions. The process of focused strategic or hoshin planning is introduced and reviewed. This model illustrates how a nursing department planned a focused strategic direction for outcomes evaluation. This discussion includes the dedication of resources, the focusing of research priorities and a summary of the outcomes evaluation program, and the method used for implementation of the priorities. Finally, benefits of both the focused planning process and the outcomes evaluation program are discussed.

Interactions of silica nanoparticles with poly(ethylene oxide) and poly(acrylic acid): effect of the polymer molecular weight and of the surface charge.

The properties and the structure of polymer-modified silica nanoparticles were investigated by several characterization methods, with an emphasis on scattering techniques. Both bare and amino functionalized nanoparticles were used. To determine the effect of the charge, the polymer used was either nonionic poly(ethylene oxide) (PEO) or partially deprotonated poly(acrylic acid) (PAA). The particles coated with PEO were investigated by small-angle neutron scattering using the method of external contrast variation to observe the polymer coverage. The quantity adsorbed was found to be increasing with the molecular weight, and the surface type, bare or aminated, did not have a significant influence on the quantity adsorbed. The adsorption of PAA on positively charged aminated particles was investigated by dynamic light scattering and zeta potential measurements. A charge reversal, from positive to negative, was induced by the presence of PAA. Through the derivation of the structure factor, small-angle X-ray scattering provided significant information on the formation of aggregates at low PAA concentrations.