Structure and Optical Properties of Titania-PDMS Hybrid Nanocomposites Prepared by In Situ Non-Aqueous Synthesis.

Organic-inorganic hybrid materials are attractive due to the combination of properties from the two distinct types of materials. In this work, transparent titania-polydimethylsiloxane hybrid materials with up to 15.5 vol. % TiO2 content were prepared by an in situ non-aqueous method using titanium (IV) isopropoxide and hydroxy-terminated polydimethylsiloxane as precursors. Spectroscopy (Fourier transform infrared, Raman, Ultraviolet-visible, ellipsometry) and small-angle X-ray scattering analysis allowed to describe in detail the structure and the optical properties of the nanocomposites. Titanium alkoxide was successfully used as a cross-linker and titania-like nanodomains with an average size of approximately 4 nm were shown to form during the process. The resulting hybrid nanocomposites exhibit high transparency and tunable refractive index from 1.42 up to 1.56, depending on the titania content.

Functionalized TiO2 nanoparticles by single-step hydrothermal synthesis: the role of the silane coupling agents.

A simple, robust and versatile hydrothermal synthesis route to in situ functionalized TiO2 nanoparticles was developed using titanium(IV) isopropoxide as Ti-precursor and selected silane coupling agents (3-aminopropyltriethoxysilane (APTES), 3-(2-aminoethylamino)propyldimethoxymethylsilane (AEAPS), and n-decyltriethoxysilane (DTES)). Spherical nanoparticles (ca. 9 nm) with narrow size distribution were obtained by using DTES or by synthesis performed without silane coupling agents. Rod-like nanoparticles along with 9 nm spherical nanoparticles were formed using aminosilane coupling agents because of a combination of oriented attachment of nanoparticles and specific adsorption of the aminosilane on crystallographic faces of anatase nanoparticles. The nanoparticles were functionalized in situ and became hydrophobic as silanes reacted to form covalent bonds on the surface of TiO2. The versatility of the aqueous synthesis route was demonstrated, and by selecting the type of silane coupling agent the surface properties of the TiO2 nanoparticles could be tailored. This synthesis route has been further developed into a two-step synthesis to TiO2-SiO2 core-shell nanoparticles. Combustion of the silane coupling agents up to 700 °C leads to the formation of a nanometric amorphous SiO2 layer, preventing growth and phase transition of the in situ functionalized nanoparticles.

Which factors decided general practitioners' choice of hospital on behalf of their patients in an area with free choice of public hospital? A questionnaire study.

BACKGROUND: Parts of New Public Management-reforms of the public sector depend on introduction of market-like mechanisms to manage the sector, like free choice of hospital. However, patients may delegate the choice of hospital to agents like general practitioners (GPs). We have investigated which factors Danish GPs reported as decisive for their choice of hospital on behalf of patients, and their utilisation of formal and informal data sources when they chose a hospital on behalf of patients. METHODS: Retrospective questionnaire study of all of the 474 GPs practising in three counties which constituted a single uptake area. Patients were free to choose a hospital in another county in the country. The GPs were asked about responsibility for choice of the latest three patients referred by the GP to hospital; which of 16 factors influenced the choice of hospital; which of 15 sources of information about clinical quality at various hospitals/departments were considered relevant, and how often were six sources of information about waiting time utilised. RESULTS: Fifty-one percent (240 GPs) filled in and returned the questionnaire. One hundred and eighty-three GPs (76%) reported that they perceived that they chose the hospital on behalf of the latest referred patient. Short distance to hospital was the most common reason for choice of hospital.The most frequently used source of information about quality at hospital departments was anecdotal reports from patients referred previously, and the most important source of information about waiting time was the hospitals' letters of confirmation of referrals. CONCLUSIONS: In an area with free choice of public hospital most GPs perceived that they chose the hospital on behalf of patients. Short distance to hospital was the factor which most often decided the GPs' choice of hospital on behalf of patients. GPs attached little weight to official information on quality and service (waiting time) at hospitals or departments, focusing instead on informal sources like feedback from patients and colleagues and their experience with cooperation with the department or hospital.

Patients' experience of choosing an outpatient clinic in one county in Denmark: results of a patient survey.

BACKGROUND: Research on patients' choice of hospital has focused on inpatients' rather than outpatients' choice of provider. We have investigated Danish outpatients' awareness and utilisation of freedom of choice of provider; which factors influence outpatients' choice of hospital, and how socio-demographic variables influence these factors in a single uptake area, where patients were free to choose any public hospital, where care was provided free at the point of delivery, and where distance to the closest hospitals were short by international standards. METHODS: Retrospective questionnaire study of 4,232 outpatients referred to examination, treatment, or follow-up at one of nine somatic outpatient clinics in Roskilde County in two months of 2002, who had not been hospitalised within the latest 12 months. The patients were asked, whether they were aware of and utilised freedom of choice of hospital. RESULTS: Fifty-four percent (2,272 patients) filled in and returned the questionnaire. Forty-one percent of respondents were aware of their right to choose, and 53% of those patients utilised their right to choose. Awareness of freedom of choice of provider was reported to be especially high in female outpatients, patients with longer education, salaried employees in the public sector, and in patients referred to surgical specialties. Female outpatients and students were especially likely to report that they utilised their right to choose the provider. Short distance was the most important reason for outpatients' choice, followed by the GP's recommendations, short waiting time, and the patient's previous experience with the hospital. CONCLUSIONS: Outpatients' awareness and utilisation of free choice of health care provider was low. Awareness of freedom of choice of provider differed significantly by specialty and patient's gender, education and employment. Female patients and students were especially likely to choose the clinic by themselves. Most outpatients chose the clinic closest to their home, the GP's recommendation and short waiting time being the second and third most important factors behind choice.

Polypharmacy in general practice.

INTRODUCTION: Polypharmacy increases the risk of side effects and interactions. We quantified the prevalence of major polypharmacy (MPP) in a Danish county with 236,000 inhabitants, invited general practitioners (GPs) to participate in a quality improvement project and discussed the medication of 10-20 MPP patients selected by the participating GPs. MATERIAL AND METHODS: This was a prospective registry study of all prescriptions of subsidized drugs in the third quarter of 2005 for all inhabitants living in Roskilde County, Denmark. An audit was performed of the prescriptions of 220 MPP patients selected by the GPs based on a list of each MPP patient's medications. RESULTS: MPP patients constituted 2.1% of the county's population. GPs demonstrated a strong interest in auditing prescriptions. A large share of the patients selected by the GPs was treated with drugs which were no longer indicated, or with drugs with a doubtful indication. CONCLUSIONS: MPP compromises the GP's ability to manage medication of individual patients. Systematic audit of the total medication of patients should be introduced.

A class of fluorescent heterocyclic dyes revisited: photophysics, structure, and solvent effects.

The photophysical behavior of a series of 2-methylthio-5-(Z-carbonyl)thieno-[3,4-e]-3,4-dihydro-1,2,3-triazine-4-ones was investigated by absorption and emission spectroscopy in a range of solvents representing a systematic variation in polarity, polarizability, as well as hydrogen bond donating and accepting capabilities. In all the investigated compounds, the heterocyclic 6-membered ring of the chromophore is involved in interactions between electron donor and acceptor substituents on the thiophene ring. Throughout the series, the charge-donating methylthio group is kept constant, while the acceptor (Z-carbonyl) is varied between amide, ester, and ketone functionalities. The fluorescent first electronically excited state is primarily of intramolecular HOMO-LUMO charge transfer character. All members of the series exhibit solvent-dependent photophysics, although the magnitude of the dependence varies with the nature of the acceptor group. In addition to the solvent-sensitive photophysics, the investigated class of compounds shows high thermal and chemical stability. Among this class of heterocyclic dyes, the amide-substituted compound is superior with respect to high quantum yield and lifetime, and also shows the largest change in emission lifetimes and fluorescence quantum yields upon solvent variation (about 5-fold).

[Drug prescription in general practice. A descriptive examination in solo practice in the former county of Roskilde]. / Ordination af laegemidler i almen praksis. En deskriptiv undersøgelse i solopraksis i det tidligere Roskilde Amt.

INTRODUCTION: General practice is responsible for 75% of drug costs in the Danish primary health care sector, but little information is available on how drugs are prescribed or on the division of labour between GPs and receptionists. MATERIALS AND METHODS: Prospective questionnaire study by patient, GP working single-handedly and/or receptionist of contacts leading to prescribing. RESULTS: 14 practices with 25,111 enrolled citizens completed the study. During the study period GPs/receptionists prescribed drugs to 1,391 patients, 493 (35%) of which were by GPs and 898 (65%) by receptionists on behalf of the GP. 62% of the GPs' and 93% of the receptionists' prescriptions were repeat prescriptions. Plans for duration of treatment in patient records were rare, and there were significant disagreements between patients and GPs about whether follow-up and duration of treatment was planned. Two thirds of patients wanted a less expensive drug, but the price was only discussed in 10% of prescriptions. DISCUSSION: Receptionists are responsible for a large share of repeat prescriptions and, surprisingly, for new prescriptions as well. Receptionists cannot decide to stop prescribing to a patient or find the least expensive analogue drug. Therefore, the GP should participate in decision-making about prescriptions.

Automated registration of tail bleeding in rats.

An automated system for registration of tail bleeding in rats using a camera and a user-designed PC-based software program has been developed. The live and processed images are displayed on the screen and are exported together with a text file for later statistical processing of the data allowing calculation of e.g. number of bleeding episodes, bleeding times and bleeding areas. Proof-of-principle was achieved when the camera captured the blood stream after infusion of rat whole blood into saline. Suitability was assessed by recording of bleeding profiles in heparin-treated rats, demonstrating that the system was able to capture on/off bleedings and that the data transfer and analysis were conducted successfully. Then, bleeding profiles were visually recorded by two independent observers simultaneously with the automated recordings after tail transection in untreated rats. Linear relationships were found in the number of bleedings, demonstrating, however, a statistically significant difference in the recording of bleeding episodes between observers. Also, the bleeding time was longer for visual compared to automated recording. No correlation was found between blood loss and bleeding time in untreated rats, but in heparinized rats a correlation was suggested. Finally, the blood loss correlated with the automated recording of bleeding area. In conclusion, the automated system has proven suitable for replacing visual recordings of tail bleedings in rats. Inter-observer differences can be eliminated, monotonous repetitive work avoided, and a higher through-put of animals in less time achieved. The automated system will lead to an increased understanding of the nature of bleeding following tail transection in different rodent models.

A concerted mechanism for uncatalysed transfer of carbon substituents from diimides to C = C and C[triple bond]C.

We present high-level computational predictions regarding a novel uncatalysed, yet feasible, C-C bond forming reaction.

[Influencing the prescriptions of general practitioners via guidelines and feedback--secondary publication]. / Påvirkning af praktiserende laegers ordinationer via kliniske retningslinjer og feedback--sekundaerpublikation.

We investigated the effects of a multi-dimensional intervention on practice prescription patterns in five drug groups. The number of prescribed defined daily doses (DDDs) increased after the intervention, while potential savings/DDD decreased. The county's average cost/DDD fell to a level below the national average. It is possible to change general practitioners' prescription patterns without interfering with their clinical freedom or patients' access to treatment.

Changing GPs' prescription patterns through guidelines and feedback. Intervention study.

PURPOSE: To investigate whether and how a multi-dimensional intervention including clinical guidelines on the choice of medical treatment in the primary and the secondary health care sector, and individual feedback to general practices about their own and other practices' prescription patterns in five Anatomical Therapeutic Chemical classification system (ATC)-groups was followed by changes in the practices' prescription pattern. METHODS: Prospective historical registry study and a questionnaire study of GPs' self-reported use of guidelines and feedback. RESULTS: In every ATC-group the number of prescribed defined daily doses (DDDs) kept growing after the intervention, while potential savings by DDD decreased. Individual practices' changes in the prescription pattern differed by ATC-group and practices with high potential savings/DDD before the intervention showed the greatest relative reduction in potential savings/DDD. The county's average cost/DDD for the five ATC-groups declined from above the Danish average before the intervention to a level below the average cost/DDD after the intervention. In the questionnaire study (response rate: 79%), 69% of respondents had read the guidelines and 78% reported that the feedback influenced their prescription of drugs. CONCLUSIONS: The observed changes in drug costs and potential savings were not due to volume effects but a combination of price effects, including generic substitution and choice of less expensive analogues, demonstrating that it is possible to change GPs' prescription patterns without interfering with patients' access to treatment or with GPs' clinical freedom.'

Why do not all hip- and knee patients facing long waiting times accept re-referral to hospitals with short waiting time? Questionnaire study.

Patients' preferences are often assumed to be homogeneous and to favour hospitals with a short waiting time and high quality. Due to long waiting times (6 months) for artificial hip or knee implantation a Danish county in 1999-2000 offered patients on a waiting list a choice between remaining on the local hospital's waiting list with the long waiting time, or re-referral to a hospital outside the county with a shorter waiting time. Fewer patients than expected took advantage of the offer of re-referral ("accepters"): 89 of 149 patients (60%). In 2003, we asked patients about the reasons for their choice: 87% of patients responded. Respondents and non-respondents were similar by decision, choice of hospital, diagnosis and age; men were significantly more likely to respond than women. Accepters and decliners were similar by age, sex, diagnosis and the presence of a car in the household. Short distance, short transport time and previous experience with the nearby hospital were the most important reasons for choosing that hospital. Some patients appeared to be willing to accept a long waiting time, if they were told exactly when they would undergo surgery. The results of this study question the validity of the conventional wisdom, that patients are willing to travel long distances in order to receive treatment with short waiting time.

Development and validation of a reversed-phase liquid chromatographic method for analysis of degradation products of estradiol in Vagifem tablets.

A stability-indicating liquid chromatographic method for the determination of degradation products and impurities in Vagifem, estradiol vaginal tablets has been developed and validated. Vagifem is a low dose preparation containing only 25microg 17beta-estradiol in a tablet matrix of 80mg (a drug to excipient ratio of 1:3200). This paper presents the rationale for the optimization of the sample preparation in order to minimize placebo interference as well as validation data for linearity, accuracy, precision, ruggedness, specificity and limits of detection and quantification. Data shows that the method is suitable for routine analysis of minute amounts of estradiol impurities.

Relations between 77Se NMR chemical shifts of (phenylseleno)-benzenes and their molecular structures derived from nine X-ray crystal structures.

An extensive library of 77Se chemical shifts have been generated from the NMR measurements on substituted (phenylseleno)benzenes, including 33 new compounds. The variation in chemical shifts cover 265 ppm ranging from 446 to 181 ppm. Crystal structures have been determined for nine selected representatives of the substituted (phenylseleno)-benzenes. The analysis of the crystal structures supported that through-space interactions between selenium and the ortho-substituent observed in the crystal structures also are likely to be present in solution. The variation in the 77Se NMR chemical shifts can be rationalised from the intramolecular interactions with the substituent in the ortho-position. Furthermore it appears that these ortho-effects are roughly additive, and that it is the actual interactions and not the resulting conformational constraints that are responsible for the variations in the 77Se NMR chemical shifts.

Prehospital interventions: on-scene-time and ambulance-technicians' experience.

INTRODUCTION: Very little evidence is available on the experience of ambulance-personnels or on the impact of prehospital interventions on total prehospital time. HYPOTHESIS: On-scene-time increases with the number of prehospital techniques used, and ambulance-technicians achieve only limited clinical experience in prehospital techniques. METHODS: Prospective, observational registry study including 56 ambulance technicians from two ambulance stations in the mixed urban/rural county and 5,557 patients who were brought to a hospital in 1998. The number of cases in which each ambulance-technician performed various kinds of prehospital techniques, and the average on-scene time for each prehospital technique and several combinations of prehospital techniques were calculated. RESULTS: There were large differences between the number of times each technique was used. On-scene time was smallest when no techniques were used and tended to increase with the number of interventions used. On-scene-time was relatively low for patients with cardiac arrest. CONCLUSION: The Danish ambulance-technicians' curriculum includes interventions for which the technicians only achieve limited practical experience. Prehospital interventions are associated with an increase of on-scene time.