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Material shrinkage commonly occurs in additive manufacturing and compromises the fabrication quality by causing unwanted distortions or residual stresses in fabricated parts. Even though it is known that the resulting deformations and stresses are highly dependent on the writing trajectory, no effective strategy for choosing suitable trajectories has been reported to date. Here, we present a path to achieve this goal in direct laser writing, an additive manufacturing method based on photopolymerization that commonly suffers from strong shrinkage-induced effects. First, we introduce a method for measuring the shrinkage of distinct direct laser written lines. We then introduce a semi-empirical numerical model to capture the interplay of sequentially polymerized material and the resulting macroscopic effects. Finally, we implement an artificial neural network to evaluate given laser trajectories in terms of the resulting part quality. The presented approach proves feasibility of using artificial neural networks to assess the quality of 3D printing trajectories and thereby demonstrates a potential route for reducing the impact of material shrinkage on 3D printed parts.

Background Peritonitis is responsible for thousands of deaths annually in Germany alone. Even source control (SC) and antibiotic treatment often fail to prevent severe sepsis or septic shock, and this situation has hardly improved in the past two decades. Most experimental immunomodulatory therapeutics for sepsis have been aimed at blocking or dampening a specific pro-inflammatory immunological mediator. However, the patient collective is large and heterogeneous. There are therefore grounds for investigating the possibility of developing personalized therapies by classifying patients into groups according to biomarkers. This study aims to combine an assessment of the efficacy of treatment with a preparation of human immunoglobulins G, A, and M (IgGAM) with individual status of various biomarkers (immunoglobulin level, procalcitonin, interleukin 6, antigen D-related human leucocyte antigen (HLA-DR), transcription factor NF-κB1, adrenomedullin, and pathogen spectrum). Methods/design A total of 200 patients with sepsis or septic shock will receive standard-of-care treatment (SoC). Of these, 133 patients (selected by 1:2 randomization) will in addition receive infusions of IgGAM for 5 days. All patients will be followed for approximately 90 days and assessed by the multiple-organ failure (MOF) score, by the EQ QLQ 5D quality-of-life scale, and by measurement of vital signs, biomarkers (as above), and survival. Discussion This study is intended to provide further information on the efficacy and safety of treatment with IgGAM and to offer the possibility of correlating these with the biomarkers to be studied. Specifically, it will test (at a descriptive level) the hypothesis that patients receiving IgGAM who have higher inflammation status (IL-6) and poorer immune status (low HLA-DR, low immunoglobulin levels) have a better outcome than patients who do not receive IgGAM. It is expected to provide information that will help to close the knowledge gap concerning the association between the effect of IgGAM and the presence of various biomarkers, thus possibly opening the way to a personalized medicine. Trial registration EudraCT, 2016–001788-34; ClinicalTrials.gov, NCT03334006. Registered on 17 Nov 2017. Trial sponsor: RWTH Aachen University, represented by the Center for Translational & Clinical Research Aachen (contact Dr. S. Isfort). Electronic supplementary material The online version of this article (10.1186/s13063-019-3244-4) contains supplementary material, which is available to authorized users.

The effect of CNT orientation on electrical and mechanical properties is presented on the example of an ultra-high filler loaded multi-walled carbon nanotube (68 wt.% MWCNTs) epoxy-based nanocomposite. A novel manufacturing method based on hot-press infiltration through a semi-permeable membrane allows to obtain both, nanocomposites with aligned and randomly oriented CNTs (APNCs and RPNCs) over a broad filler loading range of ≈10–68 wt.%. APNCs are based on low-defected, mm-long aligned MWCNT arrays grown in chemical vapour deposition (CVD) process. Electrical conductivity and mechanical properties were measured parallel and perpendicular to the direction of CNTs. RPNCs are based on both, aligned mm-long MWCNTs and randomly oriented commercial μm-long and entangled MWCNTs (Baytube C150P, and exemplarily Arkema Graphistrength C100). The piezoresistive strain sensing capability of these high-wt.% APNCs and RPNCs had been investigated towards the influence of CNT orientations. For the highest CNT fraction of 68 wt.% of unidirectional aligned CNTs a Young’s modulus of E || ≈ 36 GPa and maximum electrical conductivity of σ || ≈ 37·10 4 S/m were achieved.

The interconnection of solar cells is one of the main process steps in photovoltaic module production. Usually solar cells are connected into strings by soldering. Due to cell thickness reduction and substantial changes of solar cell metallization, alternative interconnection techniques are required. The thermomechanically induced stress, caused by high soldering temperature and different coefficients of thermal expansion limits the long term reliability of the modules. The use of conductive adhesive enables the reduction of this thermomechanically induced stress significantly. Furthermore, conductive adhesive enables interconnection of new cells and interconnector concepts, such as heterojunction solar cells with their heat sensitive surface. Relatively costly silver (Ag) based conductive adhesives are commercially available. For cost reduction and for increase in long-term reliability reasons a carbon nanotube (CNT) based conductive adhesive has been produced and investigated. Single cell modules have been built using CNT and Ag based conductive adhesives and compared. Electroluminescence, power measurement, and contact resistance measurement among other tools have been used for evaluation.

We use fiber-level simulations to investigate the combined effects of carbon nanotube (CNT) aspect ratio and shear rate on the microstructure and electrical properties of CNT/polymer composites. In our previous studies, we studied the effects of aspect ratio at a constant shear rate as well as the effects of shear rate for a constant aspect ratio. In this study electrical properties and microstructure changes (e.g. agglomeration/deagglomeration, network strength, nanotube orientation) of CNT/polymer composites are investigated for varying aspect ratios at different shear rates. When shear rate is increased, we observe a decrease in the electrical conductivity and an increase in the anisotropy factor due to the deagglomeration and flow induced orientation. Increasing aspect ratio shifts the conductivity vs. shear rate curve to larger values and anisotropy vs. shear rate curve to lower values showing that there is a tendency for tube agglomeration when high aspect ratio nanotubes are used. On the other hand when low aspect ratio nanotubes are used, conductive networks can be more easily destroyed by the shear forces because networks formed by low aspect ratio nanotubes have lower strength than those formed by high aspect ratio nanotubes. Our results show that electrical conductivity is anisotropic with a larger component in the flow direction. The critical shear rate defined as the shear rate where the conductive network is destroyed and all components of the composite conductivity decrease to the matrix conductivity, shifts to higher values when the aspect ratio is increased. Reduced alignment and increased entanglement are the reasons of this decrease.

We report on the rheological properties of semidilute carbon nanotube (CNT)/epoxy suspensions with varying filler content prepared with different dispersion methods. We show that dispersion techniques can be distinguished by means of the rheological response. It was found that the suspensions undergo a lasting dispersion changes during the first shear sweep measurement. Shear-induced changes within the suspension can also be visualized optically. Our results demonstrate that the rheological properties are strongly influenced by the measurement procedure, which has to be known in order to guarantee reproducible and comparable results. Finally, it does not seem possible to completely reset the sample history by shear treatment. POLYM. ENG. SCI., 2011. ©2011 Society of Plastics Engineers

In this work the rheological and electrical properties of semi-dilute carbon nanotube (CNT)–epoxy suspensions have been discussed. The suspensions are produced using two types of industrially available CNTs (Nanocyl 3150 and 7000) and using two different dispersion techniques, namely 3-roll milling and sonication. In-situ optical microscopic analysis and electrical conductivity measurements have been conducted. It is shown that despite using CNTs with similar aspect ratios, the dispersability of the raw material and the time stability of the suspensions are quite different. Additionally, viscosity measurements are used to evaluate the initial dispersion quality and time stability.

We employ a fiber-level simulation technique to simulate carbon nanotube (CNT)/polymer composites in simple shear flow. This model incorporates CNT flexibility, irregular CNT equilibrium shapes and CNT interactions. Electrical conductivity of the composites is determined using a resistor network algorithm. Tunneling resistance of the insulating matrix film between nanotubes is also considered. We show that the rate of imposed shear flow influences the composite conductivity by facilitating the formation or destruction of the conductive aggregates. In addition, the conductivity evolution during shearing for different concentrations is investigated. At low concentration, percolating clusters form and break simultaneously which causes large conductivity fluctuations during the simulations. When sufficiently large concentrations are reached, percolating clusters persist during shearing and the conductivity fluctuations decrease. In agreement with previous research we determine that increasing the shear rate causes alignment of the nanotubes in the flow direction. We show that upon shearing at constant shear rate, the system attains a state with substantially constant electrical conductivity, nanotube orientation and agglomerate size that is a function of the applied shear rate. The state reached for a given shear rate is independent of the initial state of orientation and aggregation.

As continued work of scanning electron microscope visualization of carbon nanotubes (CNTs) in epoxy matrix at high accelerating voltage (from 3 to 15 kV), this study focuses on the low accelerating voltage range (from 0.3 to 5.0 kV). In the CNT/epoxy composite, the CNT contrast is observed to invert two times as the accelerating voltage increases from 0.3 to 5.0 kV. At 0.7 kV the CNT contrast shifts from bright to dark, and after 1.5 kV bright CNTs are observed again. The contrast inversion and imaging mechanism of CNTs are interpreted in correlation with the secondary electron (SE) yield curve of epoxy. At 0.3–0.6 kV the epoxy is positively charged, which results in influx of electrons (from the ground) through the CNTs. These electrons lower the potential of the CNTs and enhance the local SE emission. The bright CNTs contrast at >1.5 kV is attributed to the high SE yield resulting from the trapping of injected primary electrons (PEs) in the CNTs. At 0.7 and 1.0 kV the dark CNT contrast may be attributed to the weak PEs–CNTs interaction or to the slight charging of epoxy. Further observation suggests that latter is more likely to occur.

Visualization of embedded carbon nanotubes (CNTs) in polymer using a scanning electron microscope (SEM) has been established as a convenient technique to evaluate CNT dispersion. This technique is known as voltage contrast imaging and is different from material contrast and topographic contrast imaging. By investigating CNT/epoxy composites the voltage contrast imaging theory is further understood. Trapping of electrons at the CNT/epoxy interface induces a local potential difference which enhances the image contrast. By coating the composite with a polymer film of different thicknesses the imaging depth (i.e. from how deep the CNTs can be seen) is determined to be up to 250 nm, and is a function of the accelerating voltage of the SEM. Visibility of CNTs is found to be sensitive to the CNT dispersion and concentration, as well as to the accelerating voltage.

Polymer composites can be benefited in many ways through the addition of carbon nanotubes (CNT). For instance, CNT can build up a percolated network within the polymer matrix, which results in a composite material with electrical conductivity and piezoresistive characteristics. This has very important implications for the realization of self-stress sensing structural composites. Moreover, the remarkable optical and transport properties of CNT permit to obtain information about the stress state of the composite at different scales. In the present work, the local and global stress response of SWCNT–epoxy composites is characterised by simultaneous Raman spectroscopic and electrical measurements on nanocomposite specimens submitted to different levels of surface strain. Both the Raman G′-band resonance frequency and the electrical resistance of the composite are found to change monotonically with strain until an inflection point is reached at ∼1.5% strain. Increased sensitivity of the piezoresistive network and lower load transfer efficiency occur beyond this strain level, and are considered to be the result of CNT slippage from the polymer. The reversibility of the stress sensitivity of the composites is verified by performing cyclic loading tests. Hysteresis loop are found to develop earlier on the Raman curves as in the resistance curves, which indicates that even at low strain levels, permanent damage is induced in the vicinity of carbon nanotubes. The use of Raman spectroscopy in combination with electrical methods provides a further insight on the stress sensing capabilities of CNT and the factors which affect the sensitivity and reproducibility of this behaviour.

Destruction and re-formation of conductive filler networks in a low viscous carbon nanotube (CNT)/epoxy system were investigated by online rheological, electric and optical measurements. A combined experimental setup allowed for a well-defined shear deformation of the suspension which led to a decrease in the electrical conductivity by three orders of magnitude due to network destruction and agglomerate size reduction. Subsequent to the shear induced deformation, a complete recovery of the conductivity was observed. In contrast, persistent changes in the microstructure after different shear treatments have been observed. A simple model combining classical electric percolation and time-dependent cluster aggregation was adopted to give a quantitative description of the recovery process. Recovery and aggregation process of CNT in epoxy are comparable with the behaviour in high viscous matrix systems.

Controlling the electrical conductivity is a critical issue when processing material systems consisting of an insulating matrix filled with conductive particles. We provide experimental evidence that given shear rates result in specific conductivity levels in such different systems as high-viscosity carbon nanotube/polymer melt or low-viscosity carbon nanotube/epoxy fiber suspensions. The steady-state conductivities are independent of the initial state of the dispersion. The observed behavior is modeled phenomenologically by the competition between build-up and destruction of conductive filler network. A particle-level simulation of flowing fiber suspension also reflects the observed behavior. Our results show that properties of particulate suspensions can be controlled by steady shear. They should be considered to obtain reproducible properties in shear-based processing technologies as injection molding or resin transfer molding.

Single-walled carbon nanotubes (SWCNT) were incorporated into different epoxy matrices to monitor the internal stresses arising from the curing process. The curing reaction of the neat and SWCNT-modified epoxies was investigated by differential scanning calorimetry and parallel-plate rheometry. In situ Raman spectroscopy and electrical conductivity measurements were performed in parallel and the ongoing changes at both spectra were interpreted in terms of evolving stresses. Preliminary investigations were necessary to analyse the temperature dependence of the SWCNT Raman spectra, and its contribution to the overall shifts observed at the curing experiments. Thermal compressive strains were found to develop in the samples only below their glass transition temperature, pointing at a stress releasing effect above it. Chemical shrinkage effects were found to be negligible, or at least undetectable with our technique, in comparison to the temperature-induced Raman shifts.

Given their unique set of properties, carbon nanotubes are rapidly gaining importance as stress/damage sensors in addition to as mere reinforcing elements in polymer composites. In this work, single-walled carbon nanotubes (SWCNT) are used to monitor internal stresses developing during the curing process of thermoset materials. SWCNT-epoxy composites with high dispersion quality were obtained via calandering. In situ Raman spectroscopy was used to identify chemical and thermal induced stresses by following the changes in the G’-band versus time and temperature. Thermal shrinkage prompts a pronounced effect on the spectral shifts of the composite, pointing at its dominant role (over chemical shrinkage) on the development of the internal stress field. Above Tg, Raman shifts due to temperature increase are found to be negligible, confirming the existence of a stress releasing mechanism. Shift rate of the composites cooling from their processing temperatures depended on the combination of matrix/SWCNT type, pointing at the role of interfacial strength on the load transfer efficiency.

A PSPICE model for organic thin-film transistors (OFETs) employing poly(3-hexylthiophene-2,5-diyl) (P3HT) is derived. This model is based on the standard MOSFET Berkeley Short-channel IGFET Model equations, where the voltage dependences of the charge carrier mobility and the bulk conductivity are modeled by additional voltage-controlled current sources. The model requires only five additional parameters, which can be extracted from the output characteristics of the device. The model equations have been verified by device simulations, and the simulation results have been compared with measurements of P3HT OFETs.

This paper presents a detailed characterization of different thermosetting polymers to be used as gate dielectrics in organic thin-film transistors. Selected materials yield smooth films with good insulation properties and offer attractive processing conditions. Bottom-gate transistors were prepared using these dielectrics and compared to hybrid transistors with surface-treated SiO2 as the dielectric. Gate bias induced leakage and solvent effects were investigated by preparing metal/insulator/semiconductor devices. Poly(3-hexylthiophene) (P3HT) transistors with organic dielectrics exhibited higher channel conductivity and lower mobility values with respect to P3HT-hybrid transistors and pentacene transistors. The importance of dielectric/semiconductor interface was discussed by comparing the performances of pentacene and P3HT transistors produced on different dielectrics.

Background We aimed to improve the postoperative outcome of high-risk patients (American Society of Anesthesiologists class 3 and 4) recovering from colorectal cancer surgery by using recombinant human G-CSF (filgrastim) as perioperative prophylaxis. Methods In a double-blinded, placebo-controlled trial, 80 patients undergoing left-sided colorectal resection were randomized to filgrastim or placebo. Filgrastim (5 μg/kg) or placebo was administered in the afternoon on day –1, 0, and +1 relative to the operation. Primary endpoints were in a hierarchic order: quality of life (QoL) over time (determined at discharge, 2 and 6 months after operation with the European Organization for Research and Treatment of Cancer questionnaire) and the McPeek recovery score, which measures death and duration of stays in the intensive care unit and hospital. Predefined secondary endpoints were global QoL, subdomains of QoL, postoperative recovery, duration of stay, 6-month overall survival, complication rates, and cellular and immunologic parameters. Results There were no significant differences in both primary endpoints between the treatment groups. A significant improvement (P < .05) was obtained by filgrastim prophylaxis in the QoL subdomain family life /- social functioning,; thus, more patients recovered to their preoperative state (14 vs 4 with placebo) as determined by structured interviews. Duration of hospital stay (14 vs 12 days) and noninfectious complications were decreased from 8% to 3%. Conclusions High-risk patients undergoing major operation for colorectal cancer profited from filgrastim prophylaxis with regard to duration of hospital stay, noninfectious complications, social QoL, and subjective recovery from operation. These endpoints, however, were secondary, and the primary endpoints (overall QoL and the McPeek index) did not show comparable benefits. A new confirmatory trial with the successful endpoints of this trial, as well as a cost analysis, will be needed to confirm the results before a general recommendation for the prophylactic use of G-CSF in high-risk cancer patients can be given.

Nanostructured modification of polymers has opened up new perspectives for multi-functional materials. In particular, carbon nanotubes (CNTs) have the potential to realise electrically conductive polymers with improved or retaining mechanical performance. This study focuses on the evaluation of both, the electrical and thermal conductivity of nanoparticulate filled epoxy resins. We discuss the results with regard to the influence of the type of carbon nanotube (SWCNT, DWCNT and MWCNT), the relevance of surface-functionalisation (amino-functionalisation), the influence of filler content (wt% and vol%), the varying dispersibility, the aspect ratio and the specific surface area.

Postoperative outcome of patients is determined by recovery characteristics and self-reported quality of life. The first can be assessed with the McPeek score which values three aspects of recovery: mortality, postoperative critical care and duration of hospitalization. We calculated the McPeek score of 669 patients in three trials: (1) colorectal cancer surgery, (2) antihistamine/volume loading in various operations, and (3) cholecystectomy. Beforehand, the average of intensive care unit treatment and duration of hospitalization were determined for the different operations to define McPeek score points. The score was tested on reliability, validity, and sensitivity. In addition, clinical applicability was assessed in a survey. The score was reliable with similarly distributed score points in the three trials at different institutions. Inter-rater reliability was high (97% overlap). Validity was proven by moderate high correlation to convergent criteria such as complications (trial I to III r=0.43, r=0.38, r=0.60), preoperative American Society of Anesthesiologists class (ASA) (r=0.24, r=0.28, r=0.57), and age (r=0.23, r=0.32, r=0.31). The score was different between patients with and without neoplasms (P

Carbon nanotubes (CNTs) exhibit a high-potential for the reinforcement of polymers. The mechanical properties of potential matrices of fibre-reinforced polymers (FRP), such as epoxy resins, were significantly increased by low contents of carbon nanotubes (CNT) (tensile strength, Young's modulus and fracture toughness). Nano-particle-reinforced FRPs, containing carbon black (CB) and CNTs could successfully be manufactured via resin transfer moulding (RTM). A filtering effect of the nano-particles by the glass-fibre bundles was not observed. The glass-fibre-reinforced polymers (GFRP) with nanotube/epoxy matrix exhibit significantly improved matrix-dominated properties (e.g. interlaminar shear strength), while the tensile properties were not affected by the nano-fillers, due to the dominating effect of the fibre-reinforcement. The GFRP containing 0.3 wt% amino-functionalised double-wall carbon nanotubes (DWCNT-NH 2 ) exhibit an anisotropic electrical conductivity, whereas the conductivity in plane is one order of magnitude higher than out of plane.

CVD-grown multi-wall carbon nanotubes were dispersed as an electrically conductive filler in an epoxy system based on a bisphenol-A resin and an amine hardener. The application of both AC and DC electric fields during nanocomposite curing was used to induce the formation of aligned conductive nanotube networks between the electrodes. The network formation process and resulting network structure were evaluated by in situ optical microscopy and current density measurements as a function of curing time. Parameters such as field strength and nanotube weight fraction were varied. The carbon nanotube agglomeration mechanism was dominated by the electric field-induced forces acting on the nanotubes, which have a negative surface charge after processing in the epoxy. The network structure formed in AC fields was more uniform and more aligned compared to that in DC fields. The specific bulk composite conductivity of fully processed composite samples reflected the differences in the nanotube network structure. Perhaps surprisingly, the network efficiency was not enhanced by this processing method, although the approach does offer the possibility of achieving bulk conductive nanotube–polymer composites with anisotropic electrical properties and a degree of optical transparency.

In clinical sepsis research nearly all immune-modulators have demonstrated no benefit in regard to the 28-day mortality rate. Other endpoints such as quality of life have become more attractive, but clinically relevant animal models analyzing an equivalent to quality of life by measurement of sickness behavior are extremely rare. The concept of clinic modeling randomized trials was used in an animal trial to model clinical complexity and conditions of a randomized clinical trial.80 adult male Wistar rats were randomly assigned to (1) control: anesthesia and sham operation, (2) sepsis: laparotomy and peritoneal infection with human stool bacteria, (3) sepsis with antibiotic prophylaxis: cefuroxime/metronidazole and (4) sepsis with antibiotic plus a cytokine prophylaxis with granulocyte-colony stimulating factor (GCSF). Endpoints were physiological and behavioral parameters.The combination of antibiotics plus G-CSF was most effective in reducing mortality. All infected animals showed reduced open field activity acutely after infection, and recovery was improved during the 9 day follow-up in rats with prophylactic treatments. In the social interaction test, but not in the elevated plus-maze anxiety test, prophylaxis was also efficient, especially with antibiotics and G-CSF.The results show that improving sickness behavior in septic rats with G-CSF plus antibiotics may be a promising approach.

La mesure in-situ des contraintes et des deformations, couplee avec un suivi de l'etat de sante, ameliorerait la duree de vie et la surete des structures composites. Differentes techniques d'observation in-situ et d'essais non destructifs ont ete utilisees dans le passe. Cet article passe en revue les etudes et les applications possibles des methodes electriques, telles que les mesures en courant continu sur les polymeres renforces par fibres. Dans le cas des mesures en courant continu sur les polymeres renforces par fibres de carbone (CFRP). les fibres de carbone elles-memes sont utilisees comme detecteur. Dans les polymeres renforces par fibres de verre (GFRP), un charge conductrice dans la matrice, comme du noir de carbone (CB) ou des nanotubes de carbone (CNT) peut jouer le role de detecteur a resistance. Il a ete montre qu'il est possible de suivre la deformation et la ruine, ainsi que de classer les differents mecanismes de ruine en conditions de chargement statique et dynamique, en utilisant des methodes electriques. Pour pouvoir utiliser les possibilites des nanoparticules de carbone, des methodes appropriees de fabrication doivent etre trouvees. Le moulage de resine par transfert (RTM) a pu etre applique avec succes a la fabrication de GFRP renforces par des nanoparticules, contenant du CB et des CNT comme charges conductrices. Aucun filtrage des nanoparticules par les faisceaux de fibre de verre n'a ete observe. Le polymere renforce par fibres de verre, avec une matrice epoxy chargee en nanotubes, presente une ameliotration significative des proprietes determinees par la matrice, comme la resistance au cisaillement interlaminaire. Le GFRP contenant 0,3 % en masse de nanotubes de carbone a double paroi fonctionnalises (DWCNT-NH2) presente une conductivite electrique anisotrope, la conductivite dans le plan etant superieur d'un ordre de grandeur a la conductivite hors du plan.

This paper explores the use of aligned chemical vapour deposition (CVD)-grown multi-wall carbon nanotubes as a conductive filler in an epoxy system based on a bisphenol-A resin and an amine hardener. During the production of composite samples containing 0.01 wt% nanotubes, stirring rates, resin temperatures, and curing temperatures were varied. Optical microscopy of bulk samples was used to classify the degree of nanotube agglomeration. In addition, the specific bulk conductivity of the materials was analysed by AC impedance spectroscopy. The resulting electrical properties of the composites ranged from purely dielectric behaviour to bulk conductivities of 10−3 Sm−1 and were found to depend strongly on three separate stages during processing. All samples contained individually dispersed carbon nanotubes after initial shear-intensive stirring. Negative surface charges on the nanotubes led to charge-stabilised dispersions. After the addition of the hardener, the nanotubes reaggregated upon application of elevated temperatures and/or modest shear forces. The formation of the final network depended on the curing temperature of the matrix. The experimental results are compared to previous studies on nanotube and carbon black epoxy composites and are discussed with respect to aspects of colloid theory.

Selective, low cost ultraviolet detectors with a sensitivity of up to 3 mA/W in the UVC energy range were fabricated by means of Eu 3+ -doped zinc borate glass (ZBG) fibers and Si-photodiodes. Europium-doped ZBG shows highly efficient emission (613 nm) from Eu 3+ by irradiation with high-energy UV light. The Eu 3+ -doped ZBG fiber converts the incoming UV light into visible light of 613 nm and guides it to a silicon photodiode. Eu 3+ -doped ZBG fibers Zn x B 1-x O 1.5-0.5x of varying composition (x = 0.33-0.52) were produced by the melt spinning method from glass melt in air atmosphere. The fibers were then connected to the silicon photodiode surface. The wavelength of maximum sensitivity of our detector is in the far ultraviolet and can be varied between 240 and 270 nm by changing the Zn content in the glass matrix.

General design: Presentation of a new type of a study protocol for evaluation of the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and of sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). This part describes the design of the randomised, placebo controlled, double-blinded, single-centre study performed at an university hospital (n = 40 patients for each group).¶Objective: The trial design includes the following elements for a prototype protocol:¶ - The study population is restricted to patients with colorectal cancer, including a left sided resection and an increased perioperative risk (ASA 3 and 4).¶ - Patients are allocated by random to the control or treatment group.¶ - The double blinding strategy of the trial is assessed by psychometric indices.¶ - An endpoint construct with quality of life (EORTC QLQ-C30) and a recovery index (modified Mc Peek index) are used as primary endpoints. Qualitative analysis of clinical relevance of the endpoints is performed by both patients and doctors.¶ - Statistical analysis uses an area under the curve (AUC) model for improvement of quality of life on leaving hospital and two and six months after operation. A confirmatory statistical model with quality of life as the first primary endpoint in the hierarchic test procedure is used. Expectations of patients and surgeons and the negative affect are analysed by social psychological scales.¶Conclusion: This study design differs from other trials on preoperative prophylaxis and postoperative recovery, and has been developed to try a new concept and avoid previous failures.¶

This article reports a novel application of scanning Kelvin microscopy for exclusively revealing the distribution of a percolated conductive filler network in heterogeneous materials. The materials under investigation are carbon black and carbon nanotube-filled epoxies with a highly inhomogeneous conductivity distribution due to their fabrication. The Kelvin method is demonstrated to be especially suitable for resolving the resistive particle network in these kinds of composite materials with sample resistance levels in the megaohm range. Transmission optical microscopy reveals matches between the scanning Kelvin images and the sample morphologies, whereas the percolating backbone cannot be distinguished in the optical micrographs.

To avoid electrostatic charging of an insulating matrix an electrical conductivity above σ=10−6 Sm−1 is needed. At present, the most common practice to achieve this conductivity is to use a conductive filler such as carbon black. In this work, untreated catalytically-grown carbon nanotubes were dispersed in an epoxy matrix. After curing the epoxy, the electrical properties of the composite were measured in order to relate the filler volume fraction to the electrical conductivity. The intense stirring process used to disperse the carbon nanotubes has made it possible to achieve a matrix conductivity around σ=10−2 Sm−1 with filler volume fractions as low as 0.1 vol.%. These figures represent an advance on best conductivity values previously obtained with carbon black in the same epoxy matrix. These low filler fractions ensure that the mechanical properties of the matrix are not compromised.

Carbon-rich films were deposited from liquid organosilane sources tetramethylsilane (TMS), hexamethyldisilane (HMDS) and hexamethyldisilazane (HMDSN). These films generally show efficient photoluminescence (PL) at room temperature (RT), when excited with ultraviolet (UV) light. For certain preparation conditions the self-absorption in the low energy wing of the PL can be reduced below 1 cm −1 . This property together with a sufficiently high index of refraction allows for a waveguide operation mode, where the guided light is generated in the waveguide itself via PL. Particularly, a thermal post-treatment of the deposited films has a major influence on the self-absorption and on the PL.

This prospective, multicenter, single-arm, open-label Phase III study aimed to evaluate the efficacy and safety of Privigen(®) (10% liquid human intravenous immunoglobulin [IVIG], stabilized with L-proline) in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Patients received one induction dose of Privigen (2 g/kg body weight [bw]) and up to seven maintenance doses (1 g/kg bw) at 3-week intervals. The primary efficacy endpoint was the responder rate at completion, defined as improvement of ≥1 point on the adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) disability scale. The preset success criterion was the responder rate being ≥35%. Of the 31 screened patients, 28 patients were enrolled including 13 (46.4%) IVIG-pretreated patients. The overall responder rate at completion was 60.7% (95% confidence interval [CI]: 42.41%-76.43%). IVIG-pretreated patients demonstrated a higher responder rate than IVIG-naïve patients (76.9% vs. 46.7%). The median (25%-75% quantile) INCAT score improved from 3.5 (3.0-4.5) points at baseline to 2.5 (1.0-3.0) points at completion, as did the mean (standard deviation [SD]) maximum grip strength (66.7 [37.24] kPa vs. 80.9 [31.06] kPa) and the median Medical Research Council sum score (67.0 [61.5-72.0] points vs. 75.5 [71.5-79.5] points). Of 108 adverse events (AEs; 0.417 AEs per infusion), 95 AEs (88.0%) were mild or moderate in intensity and resolved by the end of study. Two serious AEs of hemolysis were reported that resolved after discontinuation of treatment. Thus, Privigen provided efficacious and well-tolerated induction and maintenance treatment in patients with CIDP.

The interconnection of solar cells is one of the main process steps in photovoltaic module production. Usually solar cells are connected into strings by soldering. The thermo mechanically induced stress, which is caused by high soldering temperature and different coefficients of thermal expansion, limits modules long-term reliability. The use of conductive adhesive enables the reduction of this stress significantly. Furthermore, alternative interconnection techniques for new cell and ribbon concepts are required. Conductive adhesives based on Silver (Ag) filler have been shown excellent to have performance compared to soldering. But the Ag costs have absolutely exploded in recent years. For production costs reduction and for increase in long-term reliability reasons, an alternative carbon nanotube (CNT) based conductive adhesive has been developed and investigated. This new approach has been successfully demonstrated in this study. Solar cells have been connected into modules with CNT based conductive adhesive and then compared to soldering.

Using a model with Lorentz force induced fluxon motion to describe transport current properties in high‐Tc ceramics, a locally varying critical current density jc(r) has been predicted. An external magnetic field Ba applied perpendicular to the transport current shifts the maximum of jc(r) from the center position of the sample to that side of the cross section where the self‐field Bs and the external field Ba have opposite directions. The calculated redistribution of the critical current density obtained with the force model is verified experimentally by measuring the asymmetric change of the magnetic self‐field close to the sample boundaries. A nearly quantitative agreement between model calculation and experiment is found by adjusting a single parameter.

WOS: 000283759400010, In this study, electrical conductivity of a vinyl ester based composite containing low content (0.05, 0.1 and 0.3 wt.%) of double and multi-walled carbon nanotubes with and without amine functional groups (DWCNTs, MWCNTs, DWCNT-NH2 and MWCNT-NH2) was investigated. The composite with pristine MWCNTs was found to exhibit the highest electrical conductivity. Experiments aimed to induce an aligned conductive network with application of an alternating current (AC) electric field during cure were carried out on the resin suspensions with MWCNTs. Formation of electric anisotropy within the composite was verified. Light microscopy (LM), scanning electron (SEM) and transmission electron microscopy (TEM) were conducted to visualize dispersion state and the extent of alignment of MWCNTs within the polymer cured with and without application of the electric field. To gain a better understanding of electric field induced effects, glass transition temperature (T-g) of the composites was measured via Differential Scanning Calorimetry (DSC). It was determined that at 0.05 wt.% loading rate of MWCNTs, the composites, cured with application of the AC electric field, possessed a higher T-g than the composites cured without application of the AC electric field, TUBITAK of Turkey; BMBF of Germany [5], The authors acknowledge TUBITAK of Turkey and BMBF of Germany for the financial support under Project No.: 5 and Poliya Polyester A.S., Istanbul for providing us with the resins used in this study. The authors would also like to thank Dr. Josef Kovacs for his valuable help in the construction of the experimental set up used to align CNTs within the polymer. The authors would also like to thank Prof. Dr. H. Mehtap Kutlu for her fruitful discussion and comments on preparation of TEM thin polymer samples.

We analyse statistical and kinetic percolation thresholds and maximum electrical conductivities of carbon nanotube epoxy composites as a function of shear forces, processing conditions, nanotube type and dimensions. Entangled and non-entangled nanotubes of different lengths (15-100 microm) and thicknesses (12-80 nm) have been obtained with three different synthesis methods based on catalytic or plasma enhanced chemical vapour deposition. The dispersions were processed either solely with a dissolver disk or additionally with a three roll calender. Care was taken to prevent unintentional shearing (e.g. through convection) in all samples that were not subject to deliberate shearing. It was found that shear forces have a similar influence on kinetic percolation thresholds and composite conductivities independent of nanotube types and dimensions.

We report a low-temperature process to manufacture an all polymer thin-film transistor avoiding curing and annealing temperatures higher than 80°C. This aspect of energy efficiency directly supports the low-cost feature of organic devices in fabrication. The process is being demonstrated by using commercially available polymers such as poly(ethylenedioxythiophene)/polystyrenesulfonate dispersion representing the source, drain and gate electrode, Norland optical adhesive NOA 75 as the gate-dielectric and regioregular poly(3-hexylthiophene-2,5-diyl) as the semiconducting polymer - all on a polyvinyl chloride substrate. Functional devices with a channel length of 25 μm and a channel width of 1 mm to 5 mm have been realized.

Solution-processed bottom-gate organic field-effect transistors (OFET) with different dielectric materials were produced and characterized. As the active semiconductor layer, regioregular poly(3-hexylthiophene) (rr-P3HT) was used. In addition to the dielectrics which have been reported in literature, various other materials with simple processing conditions were used as gate-dielectrics. Also, the dielectric properties of the polymeric layers were investigated in metal-insulator-metal capacitor structures, where the thicknesses of the films were exactly the same as they were in the OFETs. The specific volume resistivity and dielectric constant values determined were then used to explain the electrical behavior of OFETs. The devices having BCB, SU-8 and NOA74 as the dielectric layers exhibited the desired transistor characteristics, whereas the transistors with Avatrel dielectric did not, due to higher gate-leakages. As a result, SU-8 and NOA74 resins were proven to be good candidates for gate-dielectric usage in solution-processed all-polymer OFETs.

Introduction: Blinding of doctors and patients in randomised clinical trials is an essential goal to reduce bias induced by expectations. Assessment of blinding is part of the CONSORT statement check-list for reporting of randomised trials [1]. We assessed blinding of clinicians and patients in a randomised controlled trial with G-CSF versus placebo to improve the postoperative outcome of high risk colorectal cancer patients [2]. Methods: A prospective, randomised, double-blinded trial was performed to test the effectiveness of the immune modulator G-CSF (filgrastim) to improve the postoperative outcome in 80 high risk patients (ASA 3 and 4) with colorectal cancer surgery. Study drugs (G-CSF or placebo) were injected s. c. 12 h before operation, 12 and 36 h after operation. To secure blinding, syringes were filled with the study drug (filgrastim or placebo) by ward nurses and not by the study surgeon, since shaking of ampulla’s with filgrastim would induce the production of some foam. Operating surgeons, house officers, study clinicians and patients were asked to guess in a test at 3 days after operation and at discharge what patients got — placebo or G-CSF. The size of the selection bias was assessed with phi-coefficients. Results: From the randomised 80 patients 75 were included in the analysis. At day 3 after operation and at hospital discharge similar results were obtained. Clinicians correctly rated in about 70% which study drug was applied (¤ Table 1). Patients were blinded, most (68/75) expected that they got G-CSF. Conclusions: Nearly all randomised controlled clinical trials using G-CSF as study drug claimed that they performed a double-blinded clinical trial [3], but there is no trial assessing blinding. Unblinding by surgeon and study observers was probably performed by knowledge of the patient cart including the leukocyte count. Patients were blinded without any problem. Positive expectation of the study patients can by one reason for the better recovery of these patients compared to patients not included into the trial [4]. Assessment of outcome parameters should be performed by a clinician not involved in the routine care of the patients, to guarantee an unbiased data recording and assessment.

A strongly enhanced luminescence efficiency of zincborate glasses and glass fibers doped with trivalent europium or terbium is reported. The enhancement is attributed to a high content of direct gap ZnO nanocrystallites which operate as sensitizer for the rare‐earth ions. The glasses have a low softening point and are designed to be compatible with the silicon technology. Applications as scintillating devices integrated on silicon are suggested.

Quality of life (QoL) is an important outcome measure in clinical studies. However, there is little experience with the interpretation of QoL results.To guide interpretation of QoL results from a randomised controlled trial (RCT) targeting the effectiveness of the immune modulator G-CSF on postoperative recovery in high risk (ASA III/IV) colorectal cancer patients, we compared RCT data with data from a population based cohort study and norm reference data. QoL was assessed using the European Organisation for the Research and Treatment of Cancer (EORTC) QLQ-C30 and CR38 questionnaires. QoL results were analysed on discharge from hospital and six months postoperatively.Colorectal cancer patients (both from the RCT and the cohort study) showed the greatest differences in QoL scores compared to norm reference data at discharge from hospital. Six months postoperatively, global quality of life and pain approximated norm reference values indicating optimal recovery. However, deficits still appeared in scores for role functioning, physical functioning, social functioning and fatigue. The best improvements (discharge from hospital to six months postoperatively) were seen with respect to physical functioning, fatigue and pain.For further analysis of RCT data, physical functioning and fatigue scores may be more sensitive than global quality of life to detect differences in treatment effects.

International audience; We report the application of alternating electric fields for the alignment and network formation of carbon nanofibres in an epoxy resin dispersion during curing. In situ optical microscopy verified the electrostatic stabilisation of the fibres in the dispersion and the orientation and agglomeration caused by the electric field. An explanation for the interaction forces between particles and the external electric field is given taking into account electric dipoles induced on the fibres. For the cured composites, the structural anisotropy of the fibre network was evidenced by electrical measurements. A maximal anisotropy for the dc resistivity of about 10 and for the dielectric constant at 1 kHz of about 20 was found for composites with a fibre loading 1 wt.p.c.

Treatment of anastomotic leakage after colorectal resection is usually claimed to be straightforward and there are lots of paradigmatical statements of surgical opinion leaders on how to do it properly. However, in preparation for a prospective randomized trial, a consensus process including a nominal group process failed to create a common treatment algorithm for the 22 participating centers. At least decision nodes were identified and further processed applying evidence based medicine methods. Following an extensive literature search, 41 relevant contributions were identified and ranked for level of evidence: three were level I, seven were level II–2, 15 were level II–3 and 16 were level III. Treatment alternatives for anastomotic leakage in colorectal surgery are poorly supported by good data. However, identification of the level of uncertainty for the most relevant decisions is useful and has been the basis for the development of an applicable treatment algorithm.

Background: For the development of a guideline for the treatment of anastomotic leakage in a clinical trial with a G-CSF prophylaxis in patients with colorectal cancer, an evaluation of the evidence levels was performed. For abdominal lavage evidence was only obtained from non-experimental trials and animal trials. Most animal trials do not include clinical complexity. The aim of the present trial was the analysis of the interaction of abdominal lavage with various clinical interventions and especially with the study drug G-CSF. Material and Methods: In a CMRT (clinic modelling randomized trial) the complexity of the clinic was modelled including anaesthesia, i.v. antibiotics, laparotomy, inoculation of human stool bacteria, volume substitution and postoperative analgesia. Abdominal lavage was performed 24 h after contamination including macroscopic elimination of pus and faecal particles with swabs and rinsing all parts of the abdomen with 2 x 20 ml NaCl solution. Animals were randomized into three groups: (A) no lavage, (B) lavage, (C) lavage plus G-CSF prophylaxis. The primary endpoint was the 120-h mortality rate. Secondary endpoints were the phagocytic activity of granulocytes and cytokine concentrations (IL-6 and TNF-α) in the peritoneal fluid and serum. Results: The survival rate of 33% in group A was reduced to 17% in group B by abdominal lavage. In group C the survival was increased to 61% (p < 0.05 in χ 2-test). The rate of phagocytosis-positive granulocytes was increased by the G-CSF prophylaxis (p < 0.05 in the Kruskal-Wallis test), while the concentration of IL-6 and TNF (p < 0.01 and p < 0.05) was reduced in the peritoneal fluid and IL-6 also in the serum (p < 0.05). Conclusion: Abdominal lavage alone neither increased the survival rate nor modified the phagocytic activity and cytokine levels positively. In contrast, all endpoints were positively altered by the addition of G-CSF. In the clinical trial the lavage can be performed, because there is no negative interaction with G-CSR However, lavage is not recommended since there was no benefit obtained in parallel to results from clinical trials.

International audience; This letter reports on the influence of a static electric field applied by metal electrodes on the agglomeration process of carbon black CB in epoxy resin. The growth of dendrites from the anode into the material is observed in situ by optical transmission microscopy. A percolating network is seen to form, combined with a drastic reduction in the sample resistivity. This behavior can be explained by taking into account the electrostatic interaction of the charged CB particles. The final resistance for composites with a given CB content can be controlled within a range of several decades by varying the applied voltage and the curing temperature of the mixture.

Here we investigate the combined effects of carbon nanotube (CNT) properties such as aspect ratio, curvature, and tunneling length and shear rate on the microstructure and electrical conductivities of CNT/polymer composites using fiber-level simulations. Electrical conductivities are calculated using a resistor network algorithm. Results for percolation thresholds in static systems agree with predictions and experimental measurements. We show that imposed shear flow can decrease the electrical percolation threshold by facilitating the formation of conductive aggregates. In agreement with previous research, we find that lower percolation thresholds are obtained for nanotubes with high aspect ratio. Our results also show that an increase in the curvature of nanotubes can make more agglomeration and reduce the percolation threshold in sheared suspensions.

We have investigated hysteresis in pentacene-based field-effect transistors with SiO2 as gate dielectric. A clear hysteresis behavior in transfer and output characteristics is reported. Measurements show that the observed hysteresis is due to hole trapping in the pentacene film. Long time constants of the trapping/detrapping mechanism are demonstrated through transient measurements. An initialization routine to be performed prior to measurements is proposed to enable reproducible and reliable measurements on pentacene transistors.

The authors present a strategy to manufacture wavelength-selective field-effect phototransistors by employing dye-doped poly-3-hexylthiophene (P3HT) as a semiconducting layer. The dye doping of the semiconductor P3HT was achieved by blending organic molecules—coumarin 6, oxazine 1, and nile red—into the conjugated organic polymer. Illuminating these transistors with monochromatic light in the range of 400–700nm resulted in varying conductivities for certain wavelengths in dependence on the particular dye. This effect is attributed to the photogeneration of excitons on the dye molecules, which are subsequently transferred to the conjugated polymer.