We report the fabrication of a photoresponsive organic field-effect transistor (OFET) based on a stable, n-type organic semiconductor (F 16 CuPc) and low-temperature processable polymer gate dielectric. The device exhibited a photoswitching speed of much less than 10 ms and a photosensitivity of 1.5 mA/W at low optical power. Under illumination, the device produced a current gain (I light /I dark ) of 22 at V G ) 4 V. The drain current increased gradually with an increase in the illumination intensity, resulting in typical output FET characteristics. The multifunctions (photodetection, photoswitching, signal amplification) achieved by the single device can ensure very promising material for future optoelectronic applications.

Highly stable, reproducible, photosensitive organic field-effect transistors based on an n-type organic material, copper hexadecafluorophthalocyanine, and two different polymeric gate dielectrics has been reported and their performances have been compared by evaluating the surface/interface properties. The devices produced a maximum photocurrent gain (I(light)/I(dark)) of 79 at V(G) = 7 V and showed the potentiality as multifunctional optoelectronic switching applications depending upon the external pulses. The switching time of the transistor upon irradiation of light pulse, i.e., the photoswitching time of the device, was measured to be approximately 10 ms. On the basis of optical or combination of optical and electrical pulses, the electronic/optoelectronic properties of the device can be tuned efficiently. The multifunctions achieved by the single device can ensure very promising material for high density RAM and other optoelectronic applications. Furthermore, as the device geometry in the present work is not limited to rigid substrate only, it will lead to the development of flexible organic optoelectronic switch compatible with plastic substrates.

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High quality, single crystalline, ordered arrays of a p-conjugated organic molecule, N,N 0 -dioctyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C 8 ), were grown by solution processing and used to fabricate a low-cost, high-performance organic phototransistor (OPT). The single crystalline nature of the microstructure was investigated using 2D-GIXD measurement. The organic field-effect transistor fabricated using periodic arrays of elongated crystals exhibited a photoresponsivity (P) of ca. 1 A W À1 and a photo to dark current ratio (I on /I off ) of 2.5 Â 10 3 at V G ¼ 12 V and a maximum P of ca. 7 A W À1 at the high gate bias regime (V G ¼ 50 V) with an optical power of ca. 7.5 mW cm À2 . With polymeric gate dielectric, the OPT exhibited very stable n-type characteristics both in the dark and under light illumination and showed reproducible photo-switching behavior. The dependence of the photocurrent on the gate/drain voltage and on illumination intensity provided an effective way to control the number of photo-carriers generated in the active material, enabling the precise tuning of the device's performance. Performance comparison between OPTs with ordered crystal arrays and thin films of PTCDI-C 8 confirmed that the material's intrinsic properties were better realized in the crystalline device, presumably because of higher charge carrier mobility and better charge transport capability. This one-step, solution-based, self-assembly fabrication of multifunctional (photodetection, photoswitching, signal amplification) optoelectronic devices has potential to aid the development of organic semiconductors with high-quality micro/nanostructures for large-scale application and lowcost optoelectronic devices.

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We investigated whether chronic fatigue syndrome (CFS) patients have physical and/or cardiovascular de-conditioning, in 273 CFS patients and 72 healthy controls. We used laboratory tests to assess haematological, biochemical, endocrinological and immunological systems. The cardiovascular system was assessed by echocardiography and carotid echography. Body composition was determined by dual energy X-ray absorptiometry (DEXA). CFS patients had smaller left ventricular end systolic (p < 0.001) and diastolic (p = 0.008) dimensions but thinner posterior walls (p = 0.02) than corresponding values in healthy controls. Left ventricular mass was also reduced in CFS patients (p = 0.006). Both maximum (p < 0.001) and minimum (p < 0.008) diameter of the carotid artery were smaller in CFS patients. The laboratory screening tests showed significant differences in serum albumin (p = 0.05), phosphate (p = 0.02), HDL-cholesterol (p = 0.03), HDL:total cholesterol ratio (p = 0.01), triglycerides (p = 0.02), neutrophils (p = 0.01) and thyroid-stimulating hormone (p = 0.04) between CFS patients and controls. Male CFS patients had an increased percentage of fat mass compared with healthy male subjects (p = 0.02). This large group of CFS patients had evidence of physical and cardiovascular de-conditioning, suggesting that in these patients a graded exercise programme could lead to physical reconditioning and could increase their ability to perform physical activities.

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PbS particles of average diameters ranging from 9.9 to 18.0 nm have been synthesized within a polyacrylamide matrix. The percolative chains of these particles exhibit intrinsic semiconducting behavior at temperatures higher than 340 K. The estimated band gap for these particles are found to be much higher than that of bulk PbS being in the range 1.03 to 1.49 eV. The low-temperature conductivity of these composites appears to be controlled by an electron tunneling mechanism.