Transparent, flexible electrodes and sensors based on carbon nanotube thin films

Hem obtingut capes primes de Nanotubs de Carboni d'una sola paret (CNT) sobre un substrat amb un mètode molt simple, que poden ser emprades com elèctrodes flexibles i transparents en dispositius electrònics. Per tal d'obtenir dispositius reproduïbles amb propietats similars, en particular amb similar impedància Z(ω), és important relacionar les propietats elèctriques amb la quantitat de CNTs presents en la capa. Per això, hem realitzat capes primes de CNTs sobre substrats flexibles i transparents (PPC, policarbonat de propilè) amb diferents densitats de CNT. A partir d'un mètode iteratiu matemàtic i de l'Anàlisi Tèrmogravimètric (TGA) de cada mostra, hem pogut determinar la quantitat de CNTs presents en cada mostra. També n'hem fet una estimació a partir de l'espectroscòpia d'absorció òptica. Hem vist que els dos mètodes donen resultats coherents. Hem analitzat les diferents mostres mesurant la impedància elèctrica a diferents frequències, fins 110 MHz. Les capes primes amb poca densitat de CNTs són semiconductores, en canvi les denses són metàl·liques, i prou conductores per ser utilitzades com elèctrode de treball en un procés electroquímic. Podem obtenir així composites CNT-polímer conductor o CNT-metall, electroquímicament. Amb l'objectiu de les aplicacions per a sensors, utilitzant les capes primes de CNT com elèctrode de treball hem obtingut composites CNT-polímer conductor, depositant-hi electroquímicament un polímer conductor, polipirrol o polianilina. Hem analitzat les propietats del dispositiu com a sensor electroquímic, observant la seva resposta en funció del pH, mesurant el potencial en circuit obert en funció del pH de la solució, entre 1 i 13. Els resultats mostren una bona sensibilitat, linearitat i estabilitat. Per això, els dispositius CNT/polipirrol i CNT/polianilina poden tenir aplicacions com a sensors o biosensors en estat sòlid, depositats sobre qualsevol superfície de forma arbitrària, que pot ser transparent i flexible.We obtained thin films of single-walled carbon nanotubes (CNTs), which may be used as transparent, flexible electrodes in electronic devices, on a substrate using a very simple method. In order to construct reproducible devices with similar properties, in particular with similar impedance Z(ω), it is important to associate the electrical properties with the number of CNTs in a network. We prepared thin CNT networks on transparent, flexible substrates (PPC, polypropylene carbonate) with different CNT densities. The number of CNTs was estimated using a mathematical method based on the data obtained from thermo-gravimetric analysis (TGA). We were able to estimate the relative number of CNTs using optical absorption spectroscopy. These two methods are in good agreement. We also analysed the various samples using electrical impedance measurements at frequencies of up to 110 MHz. Low-density networks are semiconductors, whilst high-density networks behave like metals and are sufficiently good conductors to be used as working electrodes in electrochemical processes. It is thus possible to obtain CNT polymer and metal composite conductors electrochemically. With sensor applications in mind, we used CNT thin films as a working electrode to obtain a composite CNT-conducting polymer. This was performed by electrochemically depositing a conducting polymer ? polypyrrole or polyaniline ? on the electrode. The pH dependence of the device was measured by recording its open circuit potential in various buffer solutions. This enabled us to analyse the properties of the device as an electrochemical sensor. The results showed a good sensitivity, linearity and stability in both cases. Thus, the CNT/polypyrrole and CNT/polyaniline devices could have applications as solidstate gas sensors or biosensors when they are deposited on transparent and flexible surfaces of any shape

Predicting the Admission into Medical Studies in Germany: A Data Mining approach. Open Access at KIT

In Germany, the placement into medical studies programs is highly competitive. Even for excellent applicants success is uncertain. Tackling this uncertainty, the aim of this paper is to investigate the success of an application. Thus applicant data in the time from 2009 to 2012 was analyzed. The characteristics of the statistical patterns lead us to simple recommendations how to alter an application in order to succeed. Our results indicate that Data Mining can outperform personal predictions

Performance of serum-supplemented and serum-free media in IFNγ Elispot Assays for human T cells

The choice of serum for supplementation of media for T cell assays and in particular, Elispot has been a major challenge for assay performance, standardization, optimization, and reproducibility. The Assay Working Group of the Cancer Vaccine Consortium (CVC-CRI) has recently identified the choice of serum to be the leading cause for variability and suboptimal performance in large international Elispot proficiency panels. Therefore, a serum task force was initiated to compare the performance of commercially available serum-free media to laboratories’ own medium/serum combinations. The objective of this project was to investigate whether a serum-free medium exists that performs as well as lab-own serum/media combinations with regard to antigen-specific responses and background reactivity in Elispot. In this way, a straightforward solution could be provided to address the serum challenge. Eleven laboratories tested peripheral blood mononuclear cells (PBMC) from four donors for their reactivity against two peptide pools, following their own Standard Operating Procedure (SOP). Each laboratory performed five simultaneous experiments with the same SOP, the only difference between the experiments was the medium used. The five media were lab-own serum-supplemented medium, AIM-V, CTL, Optmizer, and X-Vivo. The serum task force results demonstrate compellingly that serum-free media perform as well as qualified medium/serum combinations, independent of the applied SOP. Recovery and viability of cells are largely unaffected by serum-free conditions even after overnight resting. Furthermore, one serum-free medium was identified that appears to enhance antigen-specific IFNγ-secretion

Hepatic intra-arterial versus intravenous fotemustine in patients with liver metastases from uveal melanoma (EORTC 18021): a multicentric randomized trial

Despite an improved antitumor efficacy as noticed by an enhanced response rate and an improved progression-free survival, the hepatic intra-arterial fotemustine did not increase the overall survival of uveal melanoma patients with liver metastases only. We propose to consider intrahepatic treatment as an experimental approac

Open-label, multicenter, single-arm phase II DeCOG-study of ipilimumab in pretreated patients with different subtypes of metastatic melanoma

Background: Ipilimumab is an approved immunotherapy that has shown an overall survival benefit in patients with cutaneous metastatic melanoma in two phase III trials. As results of registrational trials might not answer all questions regarding safety and efficacy of ipilimumab in patients with advanced melanoma seen in daily clinical practice, the Dermatologic Cooperative Oncology Group conducted a phase II study to assess the efficacy and safety of ipilimumab in patients with different subtypes of metastatic melanoma. Patients and methods: We undertook a multicenter phase II study in melanoma patients irrespective of location of the primary melanoma. Here we present data on patients with pretreated metastatic cutaneous, mucosal and occult melanoma who received up to four cycles of ipilimumab administered at a dose of 3 mg/kg in 3 week intervals. Tumor assessments were conducted at baseline, weeks 12, 24, 36 and 48 according to RECIST 1.1 criteria. Adverse events (AEs),including immune-related AEs were graded according to National Cancer Institute Common Toxicity Criteria (CTC) v.4.0. Primary endpoint was the OS rate at 12 months. Results: 103 pretreated patients received at least one dose of ipilimumab, including 83 cutaneous, seven mucosal and 13 occult melanomas. 1-year OS rates for cutaneous, mucosal and occult melanoma were 38 %,14 % and 27 %,respectively. Median OS was 6.8 months (95 % CI 5.3-9.9) for cutaneous, 9.6 months (95 % CI 1.6-11.1) for mucosal, and 9.9 months (lower 95 % CI 2.3, upper 95 % CI non-existent) for occult melanoma. Overall response rates for cutaneous, mucosal and occult melanoma were 16 %,17 % and 11 %,respectively. Eleven patients had partial response (16 %) and ten patients experienced stable disease (14 %),none achieved a complete response. Treatment-related AEs were observed in 71 patients (69 %),including 20 grade 3-4 events (19 %). No new and unexpected safety findings were noted. Conclusions: Ipilimumab is a treatment option for pretreated patients with advanced cutaneous melanoma seen in daily routine. Toxicity was manageable when treated as per protocol-specific guidelines

Graphene foam functionalized with electrodeposited nickel hydroxide for energy applications

The need of new systems for the storage and conversion of renewable energy sources is fueling the research in supercapacitors. In this work, we propose a low temperature route for the synthesis of electrodes for these supercapacitors: electrodeposition of a transition metal hydroxide-Ni(OH)₂ on a graphene foam. This electrode combines the superior mechanical and electrical properties of graphene, the large specific surface area of the foam and the large pseudocapacitance of Ni(OH)₂. We report a specific capacitance up to 900 F/g as well as specific power and energy comparable to active carbon electrodes. These electrodes are potential candidates for their use in energy applications

Graphene foam functionalized with electrodeposited nickel hydroxide for energy applications

The need of new systems for the storage and conversion of renewable energy sources is fueling the research in supercapacitors. In this work, we propose a low temperature route for the synthesis of electrodes for these supercapacitors: electrodeposition of a transition metal hydroxide–Ni(OH)2 on a graphene foam. This electrode combines the superior mechanical and electrical properties of graphene, the large specific surface area of the foam and the large pseudocapacitance of Ni(OH)2. We report a specific capacitance up to 900 F/g as well as specific power and energy comparable to active carbon electrodes. These electrodes are potential candidates for their use in energy applications

Solvothermal synthesis of SnO2/graphene nanocomposites for supercapacitor application

A facile solvent-based synthesis route based on the oxidation–reduction reaction between graphene oxide (GO) and SnCl2·2H2O has been developed to synthesize SnO2/graphene (SnO2/G) nanocomposites. The reduction of GO and the in situ formation of SnO2 nanoparticles were achieved in one step. Characterization by X-ray diffraction (XRD), ultraviolet-visible (UV–vis) absorption spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FESEM) confirmed the feasibility of using the solvothermally treated reaction system to simultaneously reduce GO and form SnO2 nanoparticles with an average particle size of 10 nm. The electrochemical performance of SnO2/graphene showed an excellent specific capacitance of 363.3 F/g, which was five-fold higher than that of the as-synthesized graphene (68.4 F/g). The contributing factors were the synergistic effects of the excellent conductivity of graphene and the nanosized SnO2 particles

High Methanol Oxidation Activity of Well-Dispersed Pt Nanoparticles on Carbon Nanotubes Using Nitrogen Doping

Pt nanoparticles (NPs) with the average size of 3.14 nm well dispersed on N-doped carbon nanotubes (CNTs) without any pretreatment have been demonstrated. Structural properties show the characteristic N bonding within CNTs, which provide the good support for uniform distribution of Pt NPs. In electrochemical characteristics, N-doped CNTs covered with Pt NPs show superior current density due to the fact that the so-called N incorporation could give rise to the formation of preferential sites within CNTs accompanied by the low interfacial energy for immobilizing Pt NPs. Therefore, the substantially enhanced methanol oxidation activity performed by N-incorporation technique is highly promising in energy-generation applications