The Fabrication and Characterization of Single‐Component Polymeric White‐Light‐Emitting Diodes

By using Ni⁰‐mediated polymerization, we have systematically synthesized a series of fluorene‐based copolymers composed of blue‐, green‐, and red‐light‐emitting comonomers with a view to producing polymers with white‐light emission. 2,7‐Dibromo‐9,9‐dihexylfluorene, {4‐(2‐[2,5‐dibromo‐4‐{2‐(4‐diphenylamino‐phenyl)‐vinyl}‐phenyl]‐vinyl)‐phenyl}‐diphenylamine (DTPA), and 2‐{2‐(2‐[4‐{bis(4‐bromo‐phenyl)amino}‐phenyl]‐vinyl)‐6‐tert‐butyl‐pyran‐4‐ylidene}‐malononitrile (TPDCM) were used as the blue‐, green‐, and red‐light‐emitting comonomers, respectively. It was found that the emission spectra of the resulting copolymers could easily be tuned by varying their DTPA and TPDCM content. Thus with the appropriate red/green/blue (RGB) unit ratio, we were able to obtain white‐light emission from these copolymers. A white‐light‐emitting diode using the polyfluorene copolymer containing 3 % green‐emitting DTPA and 2 % red‐emitting TPDCM (PG3R2) with a structure of indium tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonic acid)/PG3R2/Ca/Al was found to exhibit a maximum brightness of 820 cd m^–2 at 11 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.35), which are close to the standard CIE coordinates for white‐light emission (0.33,0.33).     

Inhibition of natural killer cell cytotoxicity by cell growth-related molecules

Certain MHC class I molecules on target cells are known to inhibit the cytotoxic action of NK cells. By using monoclonal antibody (mAb) Cho-1, we have found inhibitory non-MHC class I cell surface molecules that are noncovalently-associated with 200 kDa and 40 kDa antigens. Poly I-C-induced rat NK cells were not cytotoxic to rat fetus-derived fibroblast WFB cell line. In contrast, NK cells were cytotoxic to H-ras oncogene-induced transformants of WFB, W14 and W31. FACS analysis indicated that mAb Cho-1 reacts with WFB, but not with W14 and W31 cells. Thus, this antigen may disappear concomitantly with cell growth and transformation. Cho-1 antigens were also expressed on other NK-resistant lines, such as mouse BALB3T3 fibroblast, EL-4 lymphoma and human fibroblast HEPM. However, they were not expressed on NK-sensitive mouse YAC-1 and H-ras transformant (Brash) of BALB3T3 cells. Furthermore, treatment of target cells with IFN-gamma clearly induced the cell surface expression of Cho-1 antigens, and conferred a resistance to NK cytolysis on target cells. These data strongly suggest that Cho-1 antigen expression may correlate with target cell susceptibility to NK cells. Indeed, treatment of NK-resistant WFB as well as HEPM cells with F(ab')2 fragments of mAb Cho-1 resulted in the acquisition of susceptibility to NK cytolysis. Cho-1 antigens may be novel molecules that regulate the NK resistance of cells.     

Gait function in spastic hemiparetic patients walking barefoot, with firm shoes, and with ankle-foot orthosis

Cortical spreading depression is a wave of electrical and biochemical changes that spreads across the cerebral cortex. It has been hypothesized to be an important underlying cause of the visual disturbances occurring during the migraine aura, but this is difficult to test in animals or humans. We created a computational model of cortical spreading depression and found that during the wave of biochemical changes the spatial pattern of neural activity broke up into irregular patterns of lines and small patches of highly activated elements. The corresponding visual disturbances that would be produced by these patterns of neural activity resemble the hallucinations reported during the migraine aura, providing strong support for the cortical spreading depression hypothesis of migraine. The model also makes the testable prediction that these hallucinations move at an exponentially increasing speed across the visual field.     

A self-organizing fuzzy control of weld pool size in GMA welding processes

In arc welding processes, because of the complexity and nonlinearity of heat transfer phenomena, it is often difficult to design an effective control system based upon an exact mathematical model. In this paper, a self-organizing fuzzy control method is proposed to obtain a uniform weld quality by regulation of the surface temperature at a desired level. The proposed control system is designed to comprise a combined structure of the fuzzy SOC with conventional PD control for improving the system's stability. The control experiments show that the proposed controller guarantees a uniform weld quality for various welding conditions.     

A new synthesis procedure for titanium-containing zeolites under strong alkaline conditions and the catalytic activity for partial oxidation and photocatalytic decomposition

A new synthesis procedure for titanium-containing aluminosilicate zeolites has been obtained using a clear colloidal dispersion (sol) which was prepared with titanium isopropoxide, water, hydrochloric acid and colloidal silica, Ludox. When NaY, KL, offretite, mordenite and ZSM-5 zeolites were crystallized from the sol following conventional hydrothermal crystallization procedures, all the aluminosilicate zeolites showed the same X-ray absorption fine structure at the Ti K edge indicating framework Ti. The zeolites showed remarkable catalytic activity for the partial oxidation of cyclohexene using H₂O₂ as an oxidant and the photocatalytic decomposition of trichloroethene using water.     

Disturbance of continuous, pump administration of cardiovascular drugs by hydrostatic pressure

Administration of highly concentrated, highly potent, and therefore highly dangerous drugs with syringe pumps is common in modern anaesthesia as well as in intensive care and emergency medicine. Because of their exact flow rates down to < 1 ml/h, these pumps are predestined for delivery of drugs with short half-lives, such as catecholamines and vasodilators. But intravenous application of drugs with syringe pumps is not without problems. While it is well known that syringes not fixed correctly into the pump can empty themselves by the influence of gravity, it seems not to be known that hydrostatic pressure can influence the flow rate of a correctly connected system even during continuous infusion. In this situation a change of height of the syringe pump in relation to the patient's position can have tremendous effects on hemodynamics due to unintended acceleration or deceleration of the flow rate. This case report demonstrates that the elevation of a connected epinephrine pump while moving a cardiac surgery patient after ACB operation from the operation table into his bed led to critical increases of heart rate, blood pressure and left atrial pressure. In order to quantify the problem we repeated the situation experimentally. It could be demonstrated that the elevation of the syringe pump by 80-100 cm delivers an additional bolus of 4-5 drops as the central venous catheter outlet. Lowering the pump consecutively leads to the opposite effect. In the case reported, the accidentally administered bolus of epinephrine was 12-15 micrograms (we use a concentration of 60 micrograms/ml epinephrine for continuous infusion with syringe pumps). From this accidental observation the following conclusion can be drawn: The change of height, in relation to the patient's position, of a running syringe pump during continuous infusion of highly concentrated cardiovascular drugs may cause considerable, even life-threatening hemodynamic disorders. Even in a closed infusion system (syringe-extension-central venous catheter), hydrostatic pressure influences infusion rate. Elevation of the pump leads to unintended bolus administration, and lowering of the pump is followed by an interruption of the infusion. In the knowledge of this phenomenon, unexpected hemodynamic reactions during transport of critically ill patients cannot always be interpreted as a result of inadequate anesthesia or volume load, but may be a consequence of incorrect handling of the syringe pumps as described in this report.     

Wear and Wear Transition in Silicon Carbide Ceramics during Sliding

Wear and wear transition in silicon carbide ceramics during sliding have been investigated. Three different microstructures, i.e., solid-state-sintered silicon carbide, liquidphase-sintered silicon carbide, and a liquid-phase-sintered SiC-TiB₂ composite, were produced by hot pressing. Wear data and examinations of worn surfaces showed that the wear behavior of these silicon carbide ceramics was significantly different. In the solid-state-sintered silicon carbide, the wear occurred by a grooving process. In the liqudphase-sintered silicon carbide and composite, on the other hand, an abrupt transition in the wear mechanism from an initial grooving process to a grain pullout process occurred during the test. The transition occurred significantly earlier in the composite than in the carbide. The different wear behavior in these silicon carbide ceramics is discussed in relation to the grain or interphase boundary strength.     

Global folds of highly deuterated, methyl-protonated proteins by multidimensional NMR

The development of 15N, 13C, 2H multidimensional NMR spectroscopy has facilitated the assignment of backbone and side chain resonances of proteins and protein complexes with molecular masses of over 30 kDa. The success of these methods has been achieved through the production of highly deuterated proteins; replacing carbon-bound protons with deuterons significantly improves the sensitivity of many of the experiments used in chemical shift assignment. Unfortunately, uniform deuteration also radically depletes the number of interproton distance restraints available for structure determination, degrading the quality of the resulting structures. Here we describe an approach for improving the precision and accuracy of global folds determined from highly deuterated proteins through the use of deuterated, selectively methyl-protonated samples. This labeling profile maintains the efficiency of triple-resonance NMR experiments while retaining a sufficient number of protons at locations where they can be used to establish NOE-based contacts between different elements of secondary structure. We evaluate how this deuteration scheme affects the sensitivity and resolution of experiments used to assign 15N, 13C, and 1H chemical shifts and interproton NOEs. This approach is tested experimentally on a 14 kDa SH2/phosphopeptide complex, and a global protein fold is obtained from a set of methyl-methyl, methyl-NH, and NH-NH distance restraints. We demonstrate that the inclusion of methyl-NH and methyl-methyl distance restraints greatly improves the precision and accuracy of structures relative to those generated with only NH-NH distance restraints. Finally, we examine the general applicability of this approach by determining the structures of several proteins with molecular masses of up to 40 kDa from simulated distance and dihedral angle restraint tables.