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The design and fabrication of graphene based textile patch antennas, intended for use in the 2.45GHz ISM band, are presented. The antennas have simple geometries with rectangular, triangular, or circular shape and substrate materials made of four different fabrics suitable for wearable applications. Conductive graphene sheet is used for the active element patches of the twelve different proposed prototypes. The effects of the antenna geometry, the substrate selection and the graphene-textile fabrication process on the prototypes’ performance are studied. Several prototypes exhibit desirable characteristics, such as high gain, acceptable radiation pattern, low Specific Absorption Rate (SAR), relatively wide bandwidth, and coverage of the ISM band even under different bending conditions.

The electronic and material properties of graphene have been explored in a number of electronic and optoelectronic devices including organic and metal halide perovskite solar cells have been explored. At present, graphene-based technology is considered to have many potential applications. Moreover, graphene-related materials offer graphene-like characteristics and the tunability of chemical, electrical and physical properties through doping and functionalization. Metal halide perovskite solar cells form the most advanced photovoltaic technology, showing an exponential increase in their certified power conversion efficiency. The most pronounced challenge is the stability of these devices, which has limited their practical applications and commercialization. The synergy between the properties of metal halide perovskite semiconductors and GRMs has recently been revealed and has contributed towards the realization of highly efficient perovskite solar cells with impressive operational stability. In this work, we review the progress made in the specific field of graphene-based metal halide perovskite solar cells since 2013. The impact of exploitation of graphene and GRMs on this photovoltaic technology is multi-fold, since it has resulted in the development of high-quality perovskite crystals for the fabrication of more stable and flexible devices exhibiting high performance.

The exploitation of nanoparticles (NP), synthesized via laser ablation in liquids, in photovoltaic devices is reviewed. In particular, the impact of NPs’ incorporation into various building blocks within the solar cell architecture on the photovoltaic performance and stability is presented and analysed for the current state of the art photovoltaic technologies.

Funding Acknowledgements none A 50-year old woman had complained about dyspnea and leg swelling despite taking furosemide 80 mgr per day. Her past medical history had included radiation therapy for Hodgkin"s lymphoma, prosthetic heart valves (mechanical MV, AV- INR = 3,2) and permanent pacemaker. Also her coronary vessels were normal. On clinical examination she was non-febrile, the arterial pressure was 120/80mmHg,there was atrial fibrillation at 70 pulses/min at rest and oxygen saturation was 96%. The chest x-ray finding was left pleural effusion. The patient also had ascites. Kidney function was normal without proteinuria. The diagnostic paracentesis and biochemical analysis of ascitic fluid was indicative of transudative fluid.Cytologic analysis was negative for malignancy. Moreover,needle biopsy specimen was subjected to histopathology,which was negative for malignancy. Echocardiography had revealed normal size and function of left ventricle ( LV = 46mm-EF = 60%). The mechanical valves had normal function, without paravalvular leak or masses. Also right ventricle was normal. The pulmonary artery pressure measured by echocardiography was in the normal range (RVSP = 35mmHg), but the inferior vena cava was dilated.There were also dilated hepatic veins and hepatic vein flow reversal.There was variation> 25% in triscupid inflow with respiration. TEE had confirmed the findings of transthoracic echo with regard of prosthetic valves. CT of chest and abdomen findings were no pathologic lymphadenopathy,no pulmonary embolism and absence of tumor compressing inferior vena cava. Chest CT scan had demonstrated pericardium thickening,indicative of constrictive pericarditis. CMR was not performed because of permanent pacemaker. The final step in diagnostic algorithm was cardiac catheterization: a)the pulmonary artery systolic pressure measured during right heart catheterization was 35mmHg. b)dip & plateau’ pattern or ‘square root sign of right ventricle, i.e. pattern of accentuated early dip in diastolic pressure, followed by plateauing in mid-late diastole. c)prominent y wave of right atrium- absent x wave because of AF. d)left ventriculography was not performed because of mechanical aortic valve. At the end constrictive pericarditis was confirmed by the surgical report. According to ESC guidelines a diagnosis of constrictive pericarditis is based on the association of signs and symptoms of right heart failure and impaired diastolic filling due to pericardial constriction by one or more imaging methods, including echocardiography, CT, CMR, and cardiac catheterization. However,the most important step is the suspicion of constrictive pericarditis, especially in patients with history of radiation therapy and heart surgery. Abstract 1099 Figure.

Objective/Background Central venous tunnelled hemodialysis catheters (CVTC) are used for initial vascular access in patients with renal failure. Tip design of the CVTC may play an important role in catheter function and complication rates, influencing adequate hemodialysis treatment of these patients. Methods This prospective, observational cohort study compared the function and complication rates of two CVTCs in patients with end stage renal disease (ESRD) within a follow-up period of 24 months. The study included patients with ESRD who received either a CVTC with a split tip (ST) or a shotgun tip (SG). All patients underwent dialysis within 24 h of intervention. Blood flow was documented initially (Qb 0 ) and was followed up after 6 (Qb 6 ), 12 (Qb 12 ), and 24 (Qb 24 ) months. Analysis of blood flow and complication rates within the follow-up period was performed by questionnaires. Results In total, 185 patients were included, of whom 93 received a ST CVTC and 92 a SG CVTC. Baseline parameters did not differ significantly between groups. CVTC blood flow was not significantly different between the two devices. Thrombolytic therapy with Alteplase was used significantly more often in the ST group (29%) than in the SG group (16%) ( p p Conclusions The tip design of CVTC (split or shotgun) appears to be irrelevant for long-term blood flow during dialysis treatment. However, patients may benefit from SG catheters over ST catheters where replacement rates and thrombolytic treatment are concerned.

The effective utilization of work-function (WF) tuned solution processable graphene-based derivatives as both hole and electron transport layers in organic photovoltaic (OPV) devices is demonstrated. The systematic tuning of the functionalized graphene oxide (GO) WF took place by either photochlorination for WF increase, or lithium neutralization for WF decrease. In this way, the WF of the photochlorinated GO layer was perfectly matched with the HOMO level of two different polymer donors, enabling excellent hole transport. Meanwhile the WF of the lithium functionalized GO was perfectly matched with the LUMO level of the fullerene acceptor, enabling excellent electron transport. The utilization of these graphene-based hole and electron transport layers in PTB7:PC71BM active layer devices led to ∼19% enhancement in the power conversion efficiency (PCE) compared to that of the reference graphene free device, resulting in the highest reported PCE for graphene-based buffer layer OPVs of 9.14%. The proposed techniques open new paths towards novel material and interface engineering approaches for a wide range of new applications, including flexible electronic devices, OPVs, perovskite solar cells, organic light emitting diodes, and photosensors, as well as traditional electronic devices.

The electron field emission (FE) properties of reduced graphene oxide (rGO) cathodes produced by three different reduction methods were assessed and compared. In particular, chemical reduction techniques, using either NaOH or KOH as reducing agents, were compared with thermal reduction (TR) methods. Xray photoelectron spectroscopy (XPS) measurements revealed that different reduction techniques led to different GO lattice parameters. Furthermore, the work function measured with ultraviolet photoelectron spectroscopy (UPS) varied among the samples giving rise to different electron emission characteristics. In particular, the cathodes prepared by the TR method presented the best FE performance, showing a turnon field of as low as ca. 1.8 V mm^-1 and a field enhancement factor of ca. 1300, which was very close however to that shown by the NaOH-reduced sheets. The worst FE properties were exhibited by the KOH-reduced nanosheets. In light of the above results, the role of the different reduction techniques as well as the final rGO lattice characteristics with regards to the emission performance are evaluated and discussed.

We developed a photochemical method for the simultaneous reduction and doping of graphene oxide (GO) layers through ultraviolet laser irradiation in the presence of a dopant precursor gas. It is shown that a few seconds of irradiation is sufficient to dope the GO lattice, while the doping and reduction levels can be readily controlled upon variation of the irradiation time. Using this method, the simultaneous reduction and doping of GO with chlorine or nitrogen atoms is achieved and confirmed by Raman, FTIR and X-ray photoelectron (XPS) spectroscopy measurements. To demonstrate the potential of the approach for practical applications, the photochemical method was successfully employed for the in situ laser induced modification of prefabricated GO field effect transistors. Real time monitoring of the evolution of charge transport as a function of irradiation time reveals significant changes, a result attributed to the chemical modification of the GO lattice. The facile, rapid and room temperature nature of the photo-induced method proposed here provides unique opportunities for the cost-effective synthesis of bulk amounts of chemically modified GO for a wide range of applications spanning from transistors and sensors to transparent electrodes for lighting and photovoltaic cells.

This paper reviews recent work on the development and use of a low-temperature, laser-based method for the efficient reduction of graphene oxide (GO) films. The method utilizes a laser beam for the in-situ and nonthermal reduction of solution-processed GO layers onto arbitrary substrates. Compared to other reduction techniques, it is single-step, facile, and can be performed at room temperature in ambient atmosphere without affecting the integrity of the either the graphene lattice or the physical properties of the underling substrate. Using this method, conductive layers of reduced GO with a sheet resistance down to ~700 Ω/sq, are obtained. This is much lower than sheet resistance values reported previously for GO layers reduced by chemical means. As a proof of concept, laser-reduced GO layers were successfully utilized as the transparent anode electrodes in flexible bulk-heterojunction OPVs and as the channel material in field-effect transistors. To the best of our knowledge, this is the only example of an in-situ, postfabrication method for the reduction of GO and its implementation in fully functional opto/electronic devices. The nonthermal nature of the method combined with its simplicity and scalability, makes it very attractive for the manufacturing of future generation large-volume graphene-based opto/electronics.

Lung cancer is still the leading cause of cancer among cancer patients. Although there are novel therapies as second line treatment for NSCLC, there is an issue for elderly patients. Patients and Methods: We collected retrospectively data from 60 patients >75 years of age. Thirty of these patients received nab-paclitaxel and first line treatment and were compared to thirty patients that received only best supportive care. Results: The median life of patients at the date of disease progression, although increased by the administration of the drug (92 days versus 70) was not confirmed statistically significantly (Mann-Whitney test: W = 280, p = 0.138). The administration of drug seems to keep stable the biological condition of patients (McNemar's test: X2 = 0.033, p = 0.99). Patients with chemotherapy the death rate was increased by 50% as compared to those with best supportive care (12 vs 8), the median life until the unfortunate event surpassed statistically significantly the latter (150 days of life as compared to 108, Mann-Whitney test: W = 57.5, p = 0.045). Discussion: Nab-paclitaxel as a monotherapy could be considered as a first line treatment option for patients > 75 years of age without any previous cardiological medical history when compared to best supportive care. © Ivyspring International Publisher.

A novel planar magnetic field sensor is presented that is based on a combined flux-gate/Hall-effect arrangement capable of measuring the three components of a three-dimensional quasi-static magnetic field. The proposed device involves a thin, isotropic, circular magnetic core, the magnetization of which is driven to saturation by means of a rotating excitation-field, produced by four printed planar coils. That way, the core magnetization rotates, without Barkhausen jumps inducing a flux-density change that is sensed by a Hall device positioned at the edge of the core. The presented sensor consists of a discrete Hall device, electronic modulation-demodulation circuitry and a circular amorphous core packaged on a printed circuit board (PCB), constructed as a proof of concept for the proposed magnetic field measuring method.

In this paper, results on magnetic and magnetoelastic uniformity measurements concerning magnetostrictive ribbons are presented. Measurements are based on the magnetostrictive delay line (MDL) technique, which is used for the determination of B(H) and λ(H) loops of long magnetostrictive ribbons, wires and rods of uniform rectangular cross section. The principle of operation for the B(H) and λ(H) loop determination is based on the biasing field effect at the receiving and excitation coil of the MDL, respectively. The automated device used allowed the in situ parametric control of field, frequency, temperature and mechanical stress. The magnetic and magnetoelastic softening of amorphous Fe–Si–B ribbons, after stress-current annealing, is illustrated. This technique may be used for the non-destructive quality control of magnetostrictive ribbons and wires, used as sensing cores.

PURPOSE To evaluate an ultra-fast sequence for MR sialography requiring no post-processing and to compare the acquisition technique regarding the effect of oral stimulation with a parallel acquisition technique in patients with salivary gland diseases. MATERIALS AND METHODS 128 patients with salivary gland disease were prospectively examined using a 1.5-T superconducting system with a 30 mT/m maximum gradient capability and a maximum slew rate of 125 mT/m/sec. A single-shot turbo-spin-echo sequence (ss-TSE) with an acquisition time of 2.8 sec was used in transverse and oblique sagittal orientation. All images were obtained with and without a parallel imaging technique. The evaluation of the ductal system of the parotid and submandibular gland was performed using a visual scale of 1-5 for each side. The images were assessed by two independent experienced radiologists. An ANOVA with post-hoc comparisons and an overall two tailed significance level of p = 0.05 was used for the statistical evaluation. An intraclass correlation was computed to evaluate interobserver variability and a correlation of > 0.8 was determined, thereby indicating a high correlation. RESULTS Depending on the diagnosed diseases and the absence of abruption of the ducts, all parts of excretory ducts were able to be visualized in all patients using the developed technique with an overall rating for all ducts of 2.70 (SD +/- 0.89). A high correlation was achieved between the two observers with an intraclass correlation of 0.73. Oral application of a sialogogum improved the visibility of excretory ducts significantly (p < 0.001). In contrast, the use of a parallel imaging technique led to a significant decrease in image quality (p = 0,011). CONCLUSION The applied ss-TSE for MR sialography allows fast and sufficient visualization of the excretory ducts of the main salivary glands in patients, and no elaborate post-processing is required. Use of an oral sialogogum is suggested to improve the results of MR sialography.

In this paper a new magnetostrictive delay line set-up for sensor applications is proposed. The tri-layer set-up consists of an inner cylindrical copper core, an intermediate thin insulating layer and an outer circumferential magnetoelastic thin film. Packaging reasons require a coating-insulating layer on top of the set-up. Different Fe–Ni compositions have been tested for the magnetostrictive film. Characterization of the devices showed that negative magnetostrictive film operates as a magnetostrictive delay line set-up, even without magnetic and heat treatment. Concerning positive magnetostrictive films, heat treatment was necessary to allow the propagation and detection of the elastic pulses.

We report 80 GHz of mode-hop-free tuning from an extended cavity diode laser (ECDL) without the need for antireflection coating on the diode facet. A large continuous tuning range was achieved by using a simple electronic circuit which simultaneously varies the diode laser current and external cavity length in an appropriate ratio. The ECDL employs a commercial, single mode AlGaAs diode laser, operating at 814 nm, in a Littrow external cavity configuration. The applicability of this technique to the most commonly available single-mode diode lasers without the requirement of antireflection coating, makes it an attractive approach for the attainment of mode-hop-free tuning over extended ranges.

Except for some few cases only symptomatic cholecystolithiasis constitutes an indication for operative treatment. The gold standard meanwhile has been the laparoscopic cholecystectomy, because the method shows good results with short hospital stay. Recently there has been an intensive discussion about combination of laparoscopic techniques with natural body orifice using surgery (NOTES). These techniques permit further reduction of surgical trauma and enhancing of cosmetic results. However, the technical effort is significant and most of the times a combination (hybrid procedure) of NOTES with standard laparoscopic procedure is performed, so that we concentrated on performing a laparoscopic cholecystectomy using a single incision through the umbilicus.A 5-mm incision left deep in the umbilicus and a 10-mm incision directly below were used for creating a pneumoperitoneum and for inserting the ports for the optic and the dissector. Exposition of the gallbladder was carried out by sutures, that were penetrated from outside through the abdominal wall into the abdominal cavity and transfixed through the gallbladder in order to hang up the gallbladder like a puppet by penetrating the abdominal wall again to the outside. Removal occurred through the umbilical incision.We successfully operated on 90 patients in a 12-month period. Mean operating time was 48 (39-71) min whereby no conversion to open surgery was necessary. No intra- or postoperative complications occurred in any patient. Average hospital stay was 2.5 (2-4) days, postoperative examination showed no differences to the usual laparoscopic cholecystectomy with a good cosmetic result and no visible scars.The purpose of our study was to further improve the cosmetic results of minimally invasive surgery of the gallbladder by operating totally through the umbilicus, using 2 ports deep in the umbilicus. We thereby avoid further surgical trauma due to creating an access through another organ as is done in the NOTES technique. For this operation no special equipment like flexible endoscopes was needed as common laparoscopic instruments were used.

A continuous-wave pump-enhanced singly resonant optical parametric oscillator (OPO) directly pumped by a grating-stabilized external-cavity diode laser operating at ≈810 nm is described. The OPO was based on periodically poled LiNbO3 and could be tuned over 1.06–1.19 μm at the signal and 2.58–3.44 μm at the idler. The OPO threshold was typically 25–30 mW over the observed tuning range. Up to 4 mW of one-directional idler output was obtained for 62 mW of external-cavity diode laser pump power. The high stability of the external-cavity diode-laser pump source allowed locked, single-mode OPO operation for periods of greater than 1 h.

Einleitung: Die Behandlung der Cholezystolithiasis wird üblicherweise durch verschiedene Methoden durchgeführt: a. konservativ, b. Laparotomie und c. Laparoskopische Cholezystektomie. Über neue Behandlungsansätze durch die Kombination laparoskopischer und natürliche Körperöffnungen[for full text, please go to the a.m. URL], 127. Kongress der Deutschen Gesellschaft für Chirurgie

We report the design and development of a high repetition rate pseudospark trigger generator for operating pseudospark switches with a low impedance of approximately 50 Omega between the trigger pins. The trigger generator can be operated from a single-shot mode up to a repetition rate of 1 kHz. It produces 3 kV, 1 mus pulses into a 100 Omega load to trigger a single pseudospark gap. Also, with the addition of a self-break spark gap and pulse forming network, the trigger generator can be used to trigger a pseudospark gap with low jitter. In this configuration, it produces 300 ns, 3 kV pulses with rise time of 10 ns. The jitter between trigger pulses applied to the pseudospark is less than 1 ns.

We present the results from low current X-pinch machine capable to produce the current around 50 kA with a rise time of 50 ns. The X-pinches were made from two 5-10 mum diameter wires. The emission of EUV radiation at 13.5 nm starts from less than 10 ns time corresponding to the current flow in the wires and lasts about 100 ns. Details of dynamics of the pinch were obtained from laser shadowgraphic and time integrated images, showing formation and evolution of low density coronal plasma. The emission of EUV becomes twice in amplitude at the time of pinching within few nanoseconds rise-time. The multiple peaked structure observed in time resolved EUV and x-rays signals show the pinching and the formation of hotspots between 40 - 70 ns after the start of the current, depending on the diameter of the wires. The dynamics of the low current X-pinch in the radial as well as in the axial direction were simulated using the 2D MHD code.

Summary form only given. Though based on the geometrical optics approximation, quantitative refractive shadowgraphy can be a reliable alternative to interferometry for sensitive optical measurements of electron densities in under-critical plasmas. We carried out a careful comparison of the two methods arranging an optical set-up capable of taking simultaneously and in single-shot a shadowgram and an interferogram of laser-produced plasma bubbles in air. In the range of electron densities 0.2-1.5times1019 cm-3 and plasma bubble diameter between 30 and 60 mum, the results of both methods were virtually identical. We reported slightly better sensitivity and spatial resolution for the shadowgraphy channel. Signal-to noise estimates assigned a density sensitivity of 0.05times1019 cm-3 for shadowgraphy and 0.2times1019 cm-3 for interferometry. The smallest detected details were measured to be of 20 mum in shadowgraphy, and 30 mum in interferometry. Apart from diffraction effects, limitations to the quantitative shadowgraphy arise mainly from inverse bremsstrahlung absorption in the probed plasma. Just a 10% absorption induces a 50% systematical error in the evaluation of the peak phase-shift of the retrieved shadow graphic data. Our simulations pointed out that appropriate calibration of the shadowgram with absorption measurements can retrieve accurately density profiles even with absorptions up to 20%. Additionally, this procedure will provide information on inverse bremsstrahlung coefficients, thus opening the possibility to estimate simultaneously density and temperature profiles in under-critical plasmas.

To evaluate an ultra-fast sequence for MR sialography requiring no post-processing and to compare the acquisition technique regarding the effect of oral stimulation with a parallel acquisition technique in patients with salivary gland diseases.128 patients with salivary gland disease were prospectively examined using a 1.5-T superconducting system with a 30 mT/m maximum gradient capability and a maximum slew rate of 125 mT/m/sec. A single-shot turbo-spin-echo sequence (ss-TSE) with an acquisition time of 2.8 sec was used in transverse and oblique sagittal orientation. All images were obtained with and without a parallel imaging technique. The evaluation of the ductal system of the parotid and submandibular gland was performed using a visual scale of 1-5 for each side. The images were assessed by two independent experienced radiologists. An ANOVA with post-hoc comparisons and an overall two tailed significance level of p = 0.05 was used for the statistical evaluation. An intraclass correlation was computed to evaluate interobserver variability and a correlation of0.8 was determined, thereby indicating a high correlation.Depending on the diagnosed diseases and the absence of abruption of the ducts, all parts of excretory ducts were able to be visualized in all patients using the developed technique with an overall rating for all ducts of 2.70 (SD +/- 0.89). A high correlation was achieved between the two observers with an intraclass correlation of 0.73. Oral application of a sialogogum improved the visibility of excretory ducts significantly (p0.001). In contrast, the use of a parallel imaging technique led to a significant decrease in image quality (p = 0,011).The applied ss-TSE for MR sialography allows fast and sufficient visualization of the excretory ducts of the main salivary glands in patients, and no elaborate post-processing is required. Use of an oral sialogogum is suggested to improve the results of MR sialography.

The production of charged pions in minimum bias p+C interactions is studied using a sample of 377000 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.8 GeV/c in transverse momentum and from -0.1 to 0.5 in Feynman xF. Inclusive invariant cross sections are given on a grid of 270 bins per charge, thus offering for the first time a dense coverage of the projectile hemisphere and of the cross-over region into the target fragmentation zone. © 2007 Springer-Verlag.

A novel 2D magnetic field sensor is presented that is based on a combined Fluxgate/Hall-Effect arrangement. The proposed device involves a thin, isotropic, circular magnetic core, the magnetization of which is driven to saturation, by means of a rotating excitation-field produced by four printed planar coils. That way, the core magnetization rotates, without Barkhausen jumps inducing two orthogonal harmonic flux-density signals that are sensed respectively by two pairs of Hall devices positioned at the edge of the core. The presented sensor incorporates discrete Hall devices and electronic circuitry, as well as a 200 mm diameter amorphous core, packaged on a PCB board. However, the system can easily be implemented on a single silicon-chip, by means of standard CMOS technologies. In this case, the amorphous core is attached onto the chip that contains the Hall devices, planar coils, and electronic circuitry, according to a state-of-art low-temperature post-process

Summary form only given. In plasma physics, shadowgraphy has always been considered as an important but a qualitative diagnostic. For optically thin plasmas quantitative data can also be extracted from shadowgrams. However, in contrast to other fields of physics, quantitative shadowgraphy can rarely be found in plasma physics. Density profiles are usually retrieved by means of interferometric techniques, which can give accurate results over a wide range of plasma densities. However, they are not suitable for real-time diagnostics as the processing of the interferogram requires phase unwrapping algorithms which often demand manual intervention. The aim of our investigation is to show that quantitative shadowgraphy can be a simpler alternative to interferometric methods for two dimensional, automated, real-time characterization of low density plasmas generated by intense laser pulses in gases. We verified the accuracy of the shadowgraphic method by retrieving density profiles of several test objects (optical fibers, gas jets, plasma filaments in air) and comparing the results with interferograms. Agreement has been found for samples satisfying the Rayleigh-Gans condition. An algorithm has been developed for the retrieval of the optical path using a multigrid solver that processes in real-time a 256times256 pixel frame in about 1 second on an AMD Turion 64-bit processor. According to our numerical simulations, the technique will be able to monitor in green light plasma samples up to a thickness of 100 micrometers with an electron density of up to 1018 cm -3

We report the generation of tunable continuous-wave (cw) radiation in the blue by intracavity frequency-doubling of an all-solid-state Ti:sapphire laser in the crystal of BiB/sub 3/O/sub 6/. Wavelength tuning over the range of 373-435 nm is demonstrated and cw blue powers of 350 mW have been obtained without optimisation.

Current sheath dynamics is an important parameter for good focusing or pinching in a dense plasma focus device. In this paper, we present pinching evidence and details of the filamentary structure of the current sheath in a miniature plasma focus device using a time-resolved laser shadowgraphic technique and time-integrated optical imaging.

Summary form only given. Continuous wave optical parametric oscillators (OPOs) pumped directly by single-mode diode lasers are potentially compact, widely tunable spectroscopic sources in the near- to mid-infrared. Such devices based on periodically poled LiNbO/sub 3/ (PPLN) have been demonstrated, with thresholds as low as 16 mW being readily pumped by single-mode diodes. However, frequency stability of solitary Fabry-Perot diodes is generally poor and attempts to stabilize OPOs pumped by such diodes have previously been restricted by pump mode-hopping, limiting single-mode OPO operation to periods of around one minute.

The design and construction of a pulsed plasma focus device to be used as a portable neutron source for material analysis such as explosive detection using gamma spectroscopy is presented. The device is capable of operating at a repetitive rate of a few Hz. When deuterium gas is used, up to 105 neutrons per shot are expected to be produced with a temporal pulse width of a few tens of nanoseconds. The pulsed operation of the device and its portable size are its main advantage in comparison with the existing continuous neutron sources. Parts of the device include the electrical charging unit, the capacitor bank, the spark switch (spark gap), the trigger unit and the vacuum–fuel chamber / anode–cathode. Numerical simulations are used for the simulation of the electrical characteristics of the device including the scaling of the capacitor bank energies with total current, the pinch current, and the scaling of neutron yields with energies and currents. The MCNPX code is used to simulate the moderation of the produced neutrons in a simplified geometry and subsequently, the interaction of thermal neutrons with a test target and the corresponding prompt γ-ray generation.

We report on post-fabrication, in situ, laser induced reduction of graphene oxide (GO) field effect transistors. Our one-step method is efficient, fast, and elevates the conductivity of GO transistor channels by two orders of magnitude. Compared to other reduction techniques, it is facile and simple since it does not require any stringent experimental conditions. Most importantly, we show here that it can be applied for, in situ, post-fabrication reduction of GO devices without compromising any of its components. The physical properties of the laser-reduced graphene oxide were assessed by micro-Raman and X-ray photoelectron spectroscopy analysis and the electrical properties by electric field effect measurements. The application of this technique in other graphene-based optoelectronic devices, especially those fabricated on inexpensive and temperature sensitive flexible substrates such as plastic, is envisaged.

The method used by the author in cooperation with S. I. Goldberg and T. Ishihara in the study of harmonic mappings of bounded dilatation (J. Differential Geometry 10 (4) (1975)) is employed here to derive a Picard type theorem for quasiconformal mappings into spaces which are not necessarily hyperbolic. More precisely: if N N is a nonpositively curved Riemannian manifold of dimension n n and scalar curvature bounded away from zero, and if M M is a complete locally flat Riemannian manifold of dimension m ⩾ n m \geqslant n , then every harmonic K K -quasiconformal mapping f : M → N f:M \to N is a constant mapping. If, in addition, M M and N N are Kaehler manifolds then every conformal mapping, f : M → N f:M \to N is of rank at most n − 2 n - 2 . For m = n = 2 m = n = 2 we obtain the classical “little” theorem of Picard.

The method used by the author in deriving a Picard type theorem for quasiconformal mappings [Proc.. Amer. Math. Soc. 61 (1976), 265-27], improved by a proposition of S.-T. Yau [Amer. J. Math. 100 (1978), 197-203] is employed here to extend the Schwarz-Ahlfors lemma to harmonic quasiconformal mappings. The target space is not necessarily hyperbolic, not even negatively curved.

Summarization: The shortage of highly qualified engineers in our knowledge-based economy requires the collaborative and coordinated action of academic institutions, professional societies, industry players, and education policy makers. In particular, lifelong learning of engineers is considered as one of the most important presumptions for future growth and social welfare. The aim of this paper is to identify the needs for lifelong learning of Greek engineers, based on recent survey data publicly available by the Technical Chamber of Greece. Furthermore, we assess the approach followed by the Department of Electronics of the Technical Educational Institute of Crete (TEloC) in response to the demand for problem-based education in telecommunications and network engineering. This approach, as well as the experience gained from other actions carried out by TEloC (i.e., the establishment of a unit for lifelong learning, the organization of summer schools in hot areas of engineering, workshops offered to the academic instructors), present to be efficient strategies for lifelong learning education. Παρουσιάστηκε στο: Meeting the Growing Demand for Engineers and Their Educators 2010-2020 International Summit

Summarization: In this paper, the content of two laboratory courses developed at the Department of Electronics of the Technological Educational Institute of Crete, Greece, focused on optoelectronics and optical communications, respectively, is presented. Both of these laboratory courses were developed with the philosophy of introducing a research-oriented approach. Emphasis is given on hands-on experimentation. In such a way, students get a better understanding of the various theoretical concepts (generation of light through single mode continuous wave lasers, transmission of optical power, etc.), and become able to analyze and solve problems associated with photonics components and their integration to optical systems. Coupling of experimentation and research is facilitated with a Marie Curie EU-funded grant for the establishment of a Centre of Excellence via the transfer of knowledge in the scientific area of optoelectronics and lasers. Our approach is presented by referring to specific laboratory exercises, such as the experimental study of a variable optical attenuator developed for research purposes, the development of an X-ray high power x-pinch optoelectronic device, etc Παρουσιάστηκε στο: Frontiers in Education Conference, 36th Annual