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1.
Stud Health Technol Inform ; 301: 20-25, 2023 May 02.
Article in English | MEDLINE | ID: mdl-37172147

ABSTRACT

BACKGROUND: Artificial Intelligence (AI) has had an important impact on many industries as well as the field of medical diagnostics. In healthcare, AI techniques such as case-based reasoning and data driven machine learning (ML) algorithms have been used to support decision-making processes for complex tasks. This is used to assist medical professionals in making clinical decisions. A way of supporting clinicians is providing predicted prognoses of various ML models. OBJECTIVES: Training an ML model based on the data of a hospital and using it on another hospital have some challenges. METHODS: In this research, we applied data analysis to discover required data filters on a hospital's EHR data for training a model for another hospital. RESULTS: We applied experiments on real-world data of ELGA (Austrian health record system) and KAGes (a public healthcare provider of 20+ hospitals in Austria). In this scenario, we train the prediction model for ELGA- authorized health service providers using the KAGes data since we do not have access to the complete ELGA data. CONCLUSION: Finally, we observed that filtering the data with both feature and value selection increases the classification performance of the prediction model, which is trained for another system.


Subject(s)
Artificial Intelligence , Cardiovascular Diseases , Humans , Machine Learning , Algorithms , Delivery of Health Care , Cardiovascular Diseases/diagnosis
2.
Polymers (Basel) ; 15(4)2023 Feb 15.
Article in English | MEDLINE | ID: mdl-36850240

ABSTRACT

Well-defined phosphonate-functionalized polycarbonate with low dispersity (Ð = 1.22) was synthesized using organocatalyzed ring-opening polymerization (ROP) of novel phosphonate-based cyclic monomers. Copolymerization was also performed to access different structures of phosphonate-containing polycarbonates (PC). Furthermore, phosphonate-functionalized PC was successfully synthesized using a combination of ROP and post-modification reaction.

3.
Polymers (Basel) ; 14(23)2022 Dec 06.
Article in English | MEDLINE | ID: mdl-36501722

ABSTRACT

New single-ion hybrid electrolytes have been synthetized via an original and simple synthetic approach combining Michael addition, epoxidation, and sol-gel polycondensation. We designed an organic PEO network as a matrix for the lithium transport, mechanically reinforced thanks to crosslinking inorganic (SiO1.5) sites, while highly delocalized anions based on lithium vinyl sulfonyl(trifluoromethane sulfonyl)imide (VSTFSILi) were grafted onto the inorganic sites to produce single-ion hybrid electrolytes (HySI). The influence of the electrolyte composition in terms of the inorganic/organic ratio and the grafted VSTFSILi content on the local structural organization, the thermal, mechanical, and ionic transport properties (ionic conductivity, transference number) are studied by a variety of techniques including SAXS, DSC, rheometry, and electrochemical impedance spectroscopy. SAXS measurements at 25 °C and 60 °C reveal that HySI electrolyte films display locally a spatial phase separation with domains composed of PEO rich phase and silica/VSTFSILi clusters. The size of these clusters increases with the silica and VSTFSILi content. A maximum ionic conductivity of 2.1 × 10-5 S·cm-1 at 80 °C has been obtained with HySI having an EO/Li ratio of 20. The Li+ ion transfer number of HySI electrolytes is high, as expected for a single-ion electrolyte, and comprises between 0.80 and 0.92.

4.
Clin Ter ; 173(3): 257-264, 2022 May 25.
Article in English | MEDLINE | ID: mdl-35612341

ABSTRACT

Background: The results of mechanical thrombectomy (MT), wi-thout or with intravenous thrombolysis, were evaluated and compared in 178 patients with acute ischemic stroke (AIS) due to large vessel occlusions (LVO) at Bach Mai Hospital. Methods: A total of 178 patients with AIS due to LVO were assigned to undergo MT alone (MT-alone group) or MT preceded by intravenous alteplase (the combined group), at a dose of 0.9 mg per kilogram, administered within 4.5 hours after symptom onset (combined group). The successful recanalization rate (assessed as thrombolysis in cerebral infarction [TICI] classification of 2b-3) and the incidence of good clinical recovery outcomes (modified Rankin Scale [mRS] ≤2) after 3 months were analyzed in both groups and compared. Results: A total of 178 patients were enrolled (median age, 65 years; 55% men; median National Institutes of Health Stroke Scale [NIHSS]: 14.3). Favorable outcomes were reported in 76 patients (66.7%) in the MT-alone group and 42 patients (65.6%) in the com-bined group, with no significant between-group difference (P = 0.31 for noninferiority). However, MT alone was associated with a lower percentage of patients with successful reperfusion after MT compared with the combined group (87.7% vs. 90.6%). Mortality at 90 days was 12.2% (14 patients) in the MT-alone group and 17.2% (11 patients) in the combined group. The incidence of symptomatic intracerebral hemorrhage was not significantly different between groups (6 [5.3%] vs. 1 [1.6%]; P = 0.42). Conclusion: Among patients with AIS due to LVO in our study, MT alone was noninferior in terms of functional outcomes compared with MT preceded by the administration of intravenous alteplase within 4.5 hours after symptom onset.


Subject(s)
Brain Ischemia , Ischemic Stroke , Mechanical Thrombolysis , Stroke , Aged , Brain Ischemia/drug therapy , Brain Ischemia/therapy , Female , Fibrinolytic Agents/therapeutic use , Humans , Male , Retrospective Studies , Stroke/therapy , Thrombectomy/methods , Thrombolytic Therapy , Tissue Plasminogen Activator/therapeutic use , Treatment Outcome
5.
Macromol Rapid Commun ; 42(18): e2100181, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34142733

ABSTRACT

Herein, the synthesis of a novel nitroxide-mediated polymerization (NMP) initiator bearing a photolabile ortho-nitrobenzyl (oNB) group allowing surface-initiated NMP preparation of well-defined photoresponsive polystyrene grafted on silica nanoparticles is described. The photocleavable and photoresponsive properties of the prepared materials are demonstrated using small angle X-ray scattering (SAXS) characterization.


Subject(s)
Nanoparticles , Silicon Dioxide , Nitrogen Oxides , Polymerization , Polystyrenes , Scattering, Small Angle , X-Ray Diffraction
6.
Soft Matter ; 17(27): 6552-6565, 2021 Jul 14.
Article in English | MEDLINE | ID: mdl-34151921

ABSTRACT

In this study, poly(ethylene oxide) monomethyl ether (MPEO) of molecular weight of 5000, 10 000, and 20 000 g mol-1 were grafted onto colloidal silica nanoparticles (NPs) of a 27.6 nm diameter using two distinct "grafting to" processes. The first method was based on the coupling reaction of epoxide-end capped MPEO with amine-functionalized silica NPs, while the second method was based on the condensation of triethoxysilane-terminated MPEO onto the unmodified silica NPs. The influence of PEO molecular weight, grafting process and grafting conditions (temperature, reactant concentration, reaction time) on the PEO grafting density was fully investigated. Thermogravimetric analysis (TGA) was used to determine the grafting density which ranged from 0.12 chains per nm2 using the first approach to 1.02 chains per nm2 when using the second approach. 29Si CP/MAS NMR characterization indirectly revealed that above a grafting density value of 0.3 PEO chains per nm2, a dendri-graft PEO network was built around the silica surface which was composed of PEO chains directly anchored to the silica surface and those grafted to silica NPs by intermediate of >CH-O-Si- bonds. The colloidal stability of the particles during different steps of the grafting process was characterized by small-angle X-ray scattering (SAXS). We have found that the colloidal systems are stable whatever the achieved grafting density due to the strong repulsions between the NPs, with the strength of repulsion increasing with the molecular weight of the grafted MPEO chains.

7.
J Nanosci Nanotechnol ; 21(7): 3656-3661, 2021 07 01.
Article in English | MEDLINE | ID: mdl-33715669

ABSTRACT

The cellular effects of ultraviolet (UV)-radiated reduced-titanium dioxide (TiO2) nanoparticles were investigated on human hypopharyngeal adenocarcinoma cells (FaDu). In 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the viability of FaDu cells exposed to UV (254 nm) for 10 minutes, in the presence of reduced-TiO2 nanoparticles in rutile, was dose- and time-dependently decreased. The UV-radiated reduced-TiO2 suppressed the cell proliferation by inhibiting the expression of cell cycle kinase, cyclin dependent kinase 2 (Cdk2), and its functional regulators Cyclin E and Cyclin B1 as well as proliferation-regulating proteins of p85 regulatory sub-unit of phosphoinositide3-kinases (PI3K p85), phosphorylated protein kinase B (p-AKT/p-PKB) and phosphorylated mammalian target of rapamycin (p-mTOR). In addition, the mitochondria disintegration and deoxyribonucleic acid (DNA) damage were confirmed by detecting the accumulated Bax in cytoplasm, phosphorylated-H2A histone family member X (γ-H2AX) in chromosomes and phosphorylated checkpoint 2 (p-Chk2). Our results support that UV-activated reduced-TiO2 in rutile sensitized UV-induced proliferation suppression of FaDu cancer cells by the enhanced photocat-alytic activity.


Subject(s)
Adenocarcinoma , Nanoparticles , Apoptosis , Cell Proliferation , Humans , Titanium/pharmacology
8.
Rapid Commun Mass Spectrom ; 32(5): 423-430, 2018 Mar 15.
Article in English | MEDLINE | ID: mdl-29235689

ABSTRACT

RATIONALE: The goal of this work was to modify the dissociation pathways of polylactide (PLA) holding benzyl and hydroxyl terminations, in order to circumvent coincidence of product ions generated during collisional activation of sodiated chains, which prevented their reliable characterization. METHODS: Benzyl-, hydroxyl-terminated PLAs were ionized as ammonium adducts in positive ion mode electrospray and subjected to collision-induced dissociation (CID). Tandem mass spectrometry (MS/MS) experiments were conducted in a quadrupole time-of-flight (QTOF) instrument for safe assignment of product ions based on their elemental composition derived from accurate mass measurements. RESULTS: Adduction of ammonium to PLAs was found to induce chain fragmentation via charge-assisted processes, in great contrast to the charge-remote mechanisms experienced by sodiated molecules. The main reaction produced ions containing the ω termination only, hence allowing straightforward end-group determination. Other minor pathways were studied in detail to establish dissociation rules for ammoniated PLAs. Some reactions were found to be end-group specific, highlighting the higher reactivity of ammonium than alkali ion adducts. CONCLUSIONS: Changing the usually employed sodium-cationizing agent to ammonium was shown to induce dramatic changes in the CID behavior of PLAs. This was a simple and efficient approach to address issues encountered for end-group analysis of the particular PLA studied here.

9.
Soft Matter ; 13(38): 6689-6693, 2017 Oct 04.
Article in English | MEDLINE | ID: mdl-28948266

ABSTRACT

Herein, a membrane prepared from the self-assembly of poly(styrene-co-acrylonitrile)-b-poly(ethylene oxide)-b-poly(styrene-co-acrylonitrile) micelles is found to exhibit translocation of nano-objects dispersed in aqueous solution. With the water flow as a driving force, temporary pores are created in between the micelles to facilitate the passage of nano-objects. These temporary pores close afterwards through a self-healing mechanism. As main results, polystyrene and silica nanoparticles exhibited a selective translocation directly influenced by their size and applied pressure.

10.
J Chromatogr A ; 1462: 63-72, 2016 Sep 02.
Article in English | MEDLINE | ID: mdl-27495367

ABSTRACT

Liquid Chromatography under Limiting Conditions of Desorption (LC LCD) is a powerful separation tool for multicomponent polymer systems. This technique is based on a barrier effect of an appropriate solvent, which is injected in front of the sample, and which decelerates the elution of selected macromolecules. In this study, the barrier effects have been evaluated for triblock copolymers polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) according to the content of polystyrene (wt% PS) and PEO-block molar mass. PS-b-PEO-b-PS samples were prepared by Atom Transfer Radical Polymerization (ATRP). The presence of respective parent homopolymers was investigated by applying optimized LC LCD conditions. It was found that the barrier composition largely affects the efficiency of separation and it ought to be adjusted for particular composition range of block copolymers.


Subject(s)
Chromatography, High Pressure Liquid/methods , Polyethylene Glycols/chemistry , Polymers/chemistry , Polymers/isolation & purification , Polystyrenes/chemistry , Molecular Weight , Polymerization , Solvents
11.
J Comp Pathol ; 155(2-3): 263-266, 2016.
Article in English | MEDLINE | ID: mdl-27421619

ABSTRACT

A 9-year-old male red panda (Ailurus fulgens) became emaciated and died. Necropsy examination revealed systemic lymphadenomegaly. The liver, lungs and left kidney contained multifocal yellow nodules. Microscopical examination revealed granulomatous inflammation in the liver, lungs, kidney, spleen and lymph nodes, with numerous acid-fast bacilli. Sequencing of genetic material isolated from the tissues classified the pathogen as Mycobacterium gastri. Lymphoma was found in the liver, lungs, kidney and lymph nodes. The neoplastic cells were strongly labelled for expression of CD3, Ki67 and proliferating cell nuclear antigen by immunohistochemistry. This is the first report of M. gastri infection with T-cell lymphoma in a red panda.


Subject(s)
Ailuridae , Lymphoma, T-Cell/veterinary , Mycobacterium Infections/veterinary , Ailuridae/microbiology , Animals , Animals, Zoo/microbiology , Male , Mycobacterium
12.
Genet Mol Res ; 15(2)2016 Apr 29.
Article in English | MEDLINE | ID: mdl-27173306

ABSTRACT

Hopea chinensis Hand-Mazz (synonym H. hongayensis Tardieu), is a wind and insect pollinated species. It is a threatened species known only from two locations: Quang Ninh (Vietnam) and Guangxi (China). As an endemic species, it is worth preserving both for dipterocarp biodiversity, as well as for its medicinal use and economic importance as a fine wood. The genetic diversity and population genetic structure of H. chinensis was investigated, using natural populations distributed throughout the Ba Mun and Cai Lim islands, Quang Ninh Province, Vietnam. A total of 65 alleles were detected. The adult allelic richness was higher than that found in juveniles and seedlings in both populations. Inbreeding was found to be significant in Ba Mun adults (F(ST) = 0.139), as well as in Cai Lim juveniles and seedlings (F(ST) = 0.283 and 0.345, respectively). Evidence of a bottleneck could be detected in the juveniles and seedlings of the Cai Lim population. A Bayesian analysis and F(ST) values suggested high genetic differentiation among the age classes of the Ba Mun and Cai Lim populations. Whereas the adults of the Ba Mun population showed evidence of inbreeding, the next generations showed more potential heterozygotes. In contrast, the adults in the Cai Lim population showed no significant inbreeding, but the observed heterozygosity in the next generation was lower than expected, suggesting significant inbreeding. The H. chinensis populations on islands are developed well and showed re-generation under good condition. Thus, the forestry protector should conserve and protect the natural spatial structure of H. chinensis on each island as their natural habitats and keep them through natural regeneration.


Subject(s)
Dipterocarpaceae/genetics , Polymorphism, Genetic , Alleles , Dipterocarpaceae/physiology , Ecosystem , Endangered Species , Genome, Plant , Heterozygote , Inbreeding , Vietnam
13.
Langmuir ; 31(38): 10532-9, 2015 Sep 29.
Article in English | MEDLINE | ID: mdl-26343169

ABSTRACT

Colloidal CdSe nanoplatelets with monolayer control over their thickness can now be synthesized in solution and display interesting optical properties. From a fundamental point of view, the self-assembly of CdSe nanoplatelets can impact their optical properties through short-range interactions, and achieving control over their dispersion state in solution is of major relevance. The related issue of colloidal stability is important from an applicative standpoint in the perspective of the processing of these materials. Using UV-vis spectroscopy, we assess the colloidal stability of dispersions of CdSe nanoplatelets at different nanoparticle and ligand (oleic acid) concentrations. We unravel an optimum in oleic acid concentration for colloidal stability and show that even moderately concentrated dispersions flocculate on a time scale ranging from minutes to hours. Small-angle X-ray scattering shows that the precipitation proceeds through a face-to-face stacking of the nanoplatelets due to long-ranged van der Waals attraction. To address this issue, we coated the platelets with a carboxylic acid-terminated polystyrene, thus achieving colloidal stability while retaining the optical properties of the platelets.

14.
Macromol Rapid Commun ; 36(15): 1416-21, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26010134

ABSTRACT

High-field dynamic nuclear polarization (DNP) has emerged as a powerful technique for improving the sensitivity of solid-state NMR (SSNMR), yielding significant sensitivity enhancements for a variety of samples, including polymers. Overall, depending upon the type of polymer, the molecular weight, and the DNP sample preparation method, sensitivity enhancements between 5 and 40 have been reported. These promising enhancements remain, however, far from the theoretical maximum (>1000). Crucial to the success of DNP SSNMR is the DNP signal enhancement (εDNP ), which is the ratio of the NMR signal intensities with and without DNP. It is shown here that, for polymers exhibiting high affinity toward molecular oxygen (e.g., polystyrene), removing part of the absorbed (paramagnetic) oxygen from the solid-state samples available as powders (instead of dissolved or dispersed in a solvent) increases proton nuclear relaxation times and εDNP, hereby providing up to a two-fold sensitivity increase (i.e., a four-fold reduction in experimental time).


Subject(s)
Magnetic Resonance Spectroscopy/methods , Oxygen/chemistry , Polymers/chemistry
15.
J Chromatogr A ; 1392: 37-47, 2015 May 01.
Article in English | MEDLINE | ID: mdl-25801535

ABSTRACT

We studied molar mass limits for the LC LCD separation of parent polystyrene (PS) and poly(ethylene oxide) (PEO) homopolymers from PEO/PS based block copolymers and we identified optimized chromatographic conditions. Time delays between barriers and sample injections were 0-2-3'10. Eluent was composed of dimethylformamide (DMF) 40 wt.% and 1-chlorobutane (CLB) 60 wt.%; Barrier 1 (B1), which retained block copolymer, was composed of 100 wt.% CLB and Barrier 2 (B2), which retained PEO, was a mixture of DMF and CLB, which proportions were adjusted to studied block copolymers. With B2 composed of DMF 23 wt.% and CLB 77 wt.%, we obtained successful separation of PS23K-b-PEO35K-b-PS23K (56.5 wt.% of PS, the subscripts indicate the molar mass in kg mol(-1) of each polymer part in the block copolymer) from its parent homopolymers. With B2 adjusted to DMF 30 wt.% and CLB 70 wt.%, PS2.3K-b-PEO3.1K (42.6 wt.% of PS) was also efficiently separated from its parent homopolymers.


Subject(s)
Chromatography, Liquid/methods , Polyethylene Glycols/chemistry , Polystyrenes/chemistry , Butanes , Dimethylformamide , Molecular Weight , Solvents
16.
J Comp Pathol ; 151(2-3): 162-5, 2014.
Article in English | MEDLINE | ID: mdl-25005673

ABSTRACT

A 2-month-old Japanese black calf was presented with a history of weight loss, exophthalmos and subcutaneous oedema of the brisket. Urinalysis and serum biochemistry showed proteinuria and hypoproteinaemia suggestive of nephrotic syndrome. Microscopically, lesions in the kidney were characterized by proliferation of mesangial cells and diffuse thickening of the glomerular basement membranes with the appearance of double contours. Immune complex deposits were confirmed by electron microscopy and immunofluorescence using reagents specific for bovine immunoglobulin G, complement factor C3 and bovine viral diarrhoea virus (BVDV). Consequently, the glomerular lesion in this case was diagnosed as membranoproliferative glomerulonephritis. BVDV type 1 was detected in serum by nested reverse transcriptase polymerase chain reaction. Viral antigen was also identified in the glomeruli by immunofluorescence. These results suggest that BVDV may have been the cause of immune complex glomerulonephritis in this calf.


Subject(s)
Bovine Virus Diarrhea-Mucosal Disease/pathology , Glomerulonephritis, Membranoproliferative/veterinary , Nephrotic Syndrome/veterinary , Animals , Bovine Virus Diarrhea-Mucosal Disease/virology , Cattle , Diarrhea Virus 1, Bovine Viral , Fluorescent Antibody Technique , Glomerulonephritis, Membranoproliferative/pathology , Glomerulonephritis, Membranoproliferative/virology , Microscopy, Electron , Nephrotic Syndrome/pathology , Nephrotic Syndrome/virology
17.
Strahlenther Onkol ; 190(4): 405-7, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24429480

ABSTRACT

BACKGROUND AND PURPOSE: This study aimed to determine factors allowing the prediction of extracranial metastases in patients presenting with brain metastases at the first diagnosis of cancer. MATERIALS AND METHODS: Data from 659 patients with brain metastases upon first diagnosis of cancer were retrospectively analyzed. The parameters age, gender, Karnofsky performance score (KPS), primary tumor type and number of brain metastases were compared between 359 patients with extracranial metastases and 300 patients without extracranial metastases. Additional analyses were performed for patients with the most unfavorable and those with the most favorable characteristics. RESULTS: The comparison of patients with versus without extracranial metastases revealed significant differences between the groups in terms of KPS (p < 0.001) and number of brain metastases (p < 0.001). Of the study patients, 113 had both most unfavorable characteristics, i.e. KPS ≤ 50 and ≥ 4 brain metastases. The sensitivity for identifying patients with extracranial metastases was 82 %; specificity was 51 %. A total of 50 patients had KPS ≥ 90 and only one brain metastasis. The sensitivity for identifying patients without extracranial metastases was 86 %; specificity was 58 %. CONCLUSION: The combination of KPS and the number of brain metastases can help to predict the presence or absence of extracranial metastases.


Subject(s)
Brain Neoplasms/diagnosis , Brain Neoplasms/secondary , Carcinoma/diagnosis , Carcinoma/secondary , Proportional Hazards Models , Aged , Brain Neoplasms/mortality , Carcinoma/mortality , Female , Germany/epidemiology , Humans , Incidence , Male , Middle Aged , Prognosis , Reproducibility of Results , Risk Assessment , Sensitivity and Specificity , Survival Rate
18.
Strahlenther Onkol ; 190(1): 64-7, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24104871

ABSTRACT

BACKGROUND AND PURPOSE: This study investigated the potential prognostic value of the number of involved extracranial organs in patients with brain metastasis from non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: A total of 472 patients who received whole-brain radiotherapy (WBRT) alone with 5 × 4 Gy or 10 × 3 Gy for brain metastasis from NSCLC were included in this retrospective study. In addition to the number of involved extracranial organs, 6 further potential prognostic factors were investigated including WBRT regimen, age, gender, Karnofsky Performance Score (KPS), number of brain metastases, and the interval from cancer diagnosis to WBRT. Subgroup analyses were performed for patients with metastatic involvement of one (lung vs. bone vs. other metastasis) and two (lung + bone vs. lung+lymph nodes vs. other combinations) extracranial organs. RESULTS: The survival rates at 6 months of the patients with involvement of 0, 1, 2, 3, and ≥ 4 extracranial organs were 52, 27, 17, 4, and 14%, respectively (p<0.001). On multivariate analysis, the number of involved extracranial organs remained significant (risk ratio 1.32; 95% confidence interval 1.19-1.46; p<0.001). Age <65 years (p=0.004), KPS ≥ 70 (p<0.001), and only 1-3 brain metastases (p=0.022) were also significantly associated with survival in the multivariate analysis. In the separate analyses of patients with involvement of one and two extracranial organs, survival was not significantly different based on the pattern of extracranial organ involvement. CONCLUSION: The number of involved extracranial organs is an independent prognostic factor of survival in patients with brain metastasis from NSCLC, irrespective of the pattern of extracranial organ involvement.


Subject(s)
Brain Neoplasms , Carcinoma, Non-Small-Cell Lung , Lung Neoplasms/mortality , Radiotherapy, Conformal/mortality , Survival Rate , Aged , Aged, 80 and over , Brain Neoplasms/mortality , Brain Neoplasms/radiotherapy , Brain Neoplasms/secondary , Carcinoma, Non-Small-Cell Lung/radiotherapy , Carcinoma, Non-Small-Cell Lung/secondary , Carcinoma, Non-Small-Cell Lung/therapy , Comorbidity , Female , Germany/epidemiology , Humans , Lung Neoplasms/therapy , Male , Middle Aged , Prognosis , Retrospective Studies , Risk Factors
19.
ACS Macro Lett ; 3(7): 658-662, 2014 Jul 15.
Article in English | MEDLINE | ID: mdl-35590763

ABSTRACT

A series of anionic poly(ionic liquid)s with 1,2,3-triazolium counter cations are prepared by cation exchange between tailormade 1,3,4-trialkylated-1,2,3-triazolium iodides and a polystyrene derivative having pendant potassium bis(trifluoromethylsulfonyl)imide groups. The physical and ion-conducting properties of the resulting materials are compared to the parent potassium-containing polyelectrolyte based on 1H NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and broadband dielectric spectroscopy (BDS) measurements. Substitution of the potassium counter cation by 1,2,3-triazolium charge carriers affords polyelectrolytes with improved processability (broader solubility and removal of the crystalline behavior) as well as a substantial increase in anhydrous ionic conductivity.

20.
ACS Macro Lett ; 3(9): 922-925, 2014 Sep 16.
Article in English | MEDLINE | ID: mdl-35596360

ABSTRACT

High-field dynamic nuclear polarization (DNP) may enhance the sensitivity of solid-state NMR experiments on a wide range of systems, including synthetic polymers, owing to the transfer of electron spin polarization from radicals to nuclei upon microwave irradiation (usually at cryogenic temperatures). Provided that the radicals are homogeneously dispersed in the sample, a uniform DNP enhancement is expected for all the signals in the 13C cross-polarization magic angle spinning (CPMAS) spectrum. Here, we show that, in the case of methyl group containing polymers, a change in the cross-polarization (CP) dynamics induced by the moderate increase in sample temperature due to microwave irradiation may lead to the observation of apparent nonuniform enhancements in the DNP-enhanced 13C CPMAS spectra. This peculiar behavior should be accounted for when measuring 13C CP DNP enhancements on polymer materials, especially for heterogeneous polymer samples (for which truly nonuniform DNP enhancements could potentially be detected), or when quantitative results are sought.

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