Photocatalytic degradation of dyes and organic contaminants in water using nanocrystalline anatase and rutile TiO2

Nanocrystalline TiO₂ was synthesized by controlled hydrolysis of titanium tetraisopropoxide. The anatase phase was converted to rutile phase by thermal treatment at 1023 K for 11 h. The catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier-transform infrared absorption spectrophotometry (FT-IR) and N₂ adsorption (BET) at 77 K. This study compare the photocatalytic activity of the anatase and rutile phases of nanocrystalline TiO₂ for the degradation of acetophenone, nitrobenzene, methylene blue and malachite green present in aqueous solutions. The initial rate of degradation was calculated to compare the photocatalytic activity of anatase and rutile nanocrystalline TiO₂ for the degradation of different substances under ultraviolet light irradiation. The higher photocatalytic activity was obtained in anatase phase TiO₂ for the degradation of all substances as compared with rutile phase. It is concluded that the higher photocatalytic activity in anatase TiO₂ is due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst.     

Catalytic characteristics of MnO2 nanostructures for the O2 reduction process

Nanorods with an α type MnO(2) structure and a diameter ranging from 25 to 40 nm, along with tipped needles with a β MnO(2) structure and a diameter of 100 nm were obtained. The 25 nm diameter α MnO(2) nanorods showed the best catalytic activity for dissociation of HO(2)(-) formed during oxygen reduction in a KOH solution. The MnO(2) nanostructures preferably followed a two-electron oxygen reduction mechanism in a LiOH solution. The size of the catalyst also affected the specific capacities of the non-aqueous Li/O(2) batteries fabricated using the MnO(2) based air electrode. The highest specific capacity of 1917 mA h g(-1) was obtained for an α MnO(2) nanorod catalyst having a diameter of 25 nm. The cation present in the MnO(2) nanostructures appears to determine the catalytic activity of MnO(2).     

Efficiency optimization of green phosphorescent organic light-emitting device

Using a narrow band gap host of bis[2-(2-hydroxyphenyl)-pyridine]beryllium (Bepp₂) and green phosphorescent Ir(ppy)₃ [fac-tris(2-phenylpyridine) iridium III] guest concentration as low as 2%, high efficiency phosphorescent organic light-emitting diode (PHOLED) is realized. Current and power efficiencies of 62.5 cd/A (max.), 51.0 lm/W (max.), and external quantum efficiency (max.) of 19.8% are reported in this green PHOLED. A low current efficiency roll-off value of 10% over the brightness of 10,000 cd/m² is noticed in this Bepp₂ single host device. Such a high efficiency is obtained by the optimization of the doping concentration with the knowledge of the hole trapping and the emission zone situations in this host-guest system. It is suggested that the reported device performance is suitable for applications in high brightness displays and lighting.     

Small molecule interlayer for solution processed phosphorescent organic light emitting device

Using a 4,4′,4′′-tris(N-carbazolyl)-triphenylamine (TCTA) small molecule interlayer, we have fabricated efficient green phosphorescent organic light emitting devices by solution process. Significantly a low driving voltage of 3.0 V to reach a luminance of 1000 cd/m² is reported in this device. The maximum current and power efficiency values of 27.2 cd/A and 17.8 lm/W with TCTA interlayer (thickness 30 nm) and 33.7 cd/A and 19.6 lm/W with 40 nm thick interlayer are demonstrated, respectively. Results reveal a way to fabricate the phosphorescent organic light emitting device using TCTA small molecule interlayer by solution process, promising for efficient and simple manufacturing.     

Investigating effects of temperature on fuel properties of torrefied biomass for bio-energy systems

Torrefaction of selected agro-residues (rice straw and cotton stalk) was successfully carried out on indirectly heated, batch-type fixed-bed reactor under different reactor temperatures (200–300°C) at a fixed heating rate of 10°C/min. Our preliminary results demonstrated that the rice straw, torrefied at 275°C, exhibited higher mass yield (64%) and energy yield (84%) with better fuel properties, i.e. lower moisture content (1.2%), volatile matters (54.7%), higher fixed carbon (24.8%), and higher heating value (HHV) 18.7 MJ/kg. On the other hand, cotton stalk showed a slightly lower mass yield (56.3%) and energy yield (74.4%) compared to rice star with very high HHV 22.5 MJ/kg torrefied at a relatively lower temperature of 250°C. Interestingly, the lignocellulosic composition showed a drastic increase in the lignin content of rice straw and cotton stalk, torrefied at 275°C and 250°C, respectively, which indicates good binding ability of bio-fuel leading to improved energy density. Our present work gives an insight that the torrefied rice straw and cotton stalk could be a promising biomass feedstock for bio-energy based systems such as biomass pyrolsyis and gasification.     

Fabrication of buried microfluidic channels with observation windows using femtosecond laser photoablation and parylene-C coating

We developed an advanced method for fabricating microfluidic structures comprising channels and inputs/outputs buried within a silicon wafer based on single level lithography. We etched trenches into a silicon substrate, covered these trenches with parylene-C, and selectively opened their bottoms using femtosecond laser photoablation, forming channels and inputs/outputs by isotropic etching of silicon by xenon difluoride vapors. We subsequently sealed the channels with a second parylene-C layer. Unlike in previously published works, this entire process is conducted at ambient temperature to allow for integration with complementary metal oxide semiconductor devices for smart readout electronics. We also demonstrated a method of chip cryo-cleaving with parylene presence that allows for monitoring of the process development. We also created an observation window for in situ visualization inside the opaque silicon substrate by forming a hole in the parylene layer at the silicon backside and with local silicon removal by xenon difluoride vapor etching. We verified the microfluidic chip performance by forming a segmented flow of a fluorescein solution in an oil stream. This proposed technique provides opportunities for forming simple microfluidic systems with buried channels at ambient temperature.     

Noninvasive detection of bladder cancer with the BTA stat test

PURPOSE: We assess the sensitivity and specificity of the noninvasive BTA stat urine test for detection of primary and recurrent bladder cancer with special reference to the size, grade and stage of the tumors, and examine the effect of intravesical bacillus Calmette-Guerin treatment on the results. MATERIALS AND METHODS: A total of 250 patients recruited from 3 medical centers provided voided urine samples for the BTA stat test and cytopathological study. Of these patients 162 were monitored following resection of bladder tumors and 88 were evaluated for the first time for hematuria or irritative voiding symptoms. Each patient underwent cystoscopy. Biopsies were obtained when a bladder tumor was seen or if carcinoma in situ was suspected. The sensitivity, specificity and accuracy of the BTA stat test were compared to standard voided urine cytology. RESULTS: No tumor was found in 122 patients, primary transitional cell carcinoma was found in 71 and cystoscopy revealed recurrent tumors in 57. Overall sensitivity of the BTA stat test was 82.8% and specificity was 68.9%. Sensitivity of urine cytology was 39.8% and specificity was 95.1%. The BTA stat test detected 90.1% of the primary and 73.7% of the recurrent tumors. All patients with carcinoma in situ, high grade tumors, muscle invasive cancer and tumors larger than 2 cm. were diagnosed by the BTA stat test. CONCLUSIONS: The BTA stat test can be used as a screening test for bladder cancer in patients with hematuria or irritative voiding symptoms and for surveillance of those who have not been treated with intravesical bacillus Calmette-Guerin.     

On Configuration of Load in Radiant Furnace for Uniform Thermal Conditions

This work aimed to investigate the boundary design problem for uniform thermal conditions, when multiple three-dimensional (3-D) design objects (DOs) are placed inside the radiant furnace, and to explore the suitable configuration of DOs located inside the radiant furnace. Also the objective includes ascertaining the limit of maximum numbers of DOs that can be accommodated to get the uniform thermal conditions. To accomplish this task, 19 cases are evaluated, consisting of the different number of DOs with various configurations, located on the bottom surface of the furnace enclosure. Each case is treated as an inverse boundary design problem separately. The radiative information is calculated using the radiation element method by ray emission model (REM²). The microgenetic algorithm (MGA) is used as an optimization tool. The specularity effect of the surfaces of heaters, of surfaces of radiant enclosure, and of the DOs is taken into account. The suitability of the configuration of DOs is shown by comparing the estimated heat flux distribution on DOs. The effect of different heater power ranges on the uniformity of the heat flux distribution on DOs is discussed. With a sample case, the optimal heater power setting that produces the desired uniform thermal conditions on DOs is also given. In the present boundary design problems, to obtain the uniform thermal conditions, a pronounced effect of the configuration of DOs and the numbers of DOs is observed.     

Soluble processed low-voltage and high efficiency blue phosphorescent organic light-emitting devices using small molecule host systems

We report low voltage driving and highly efficient blue phosphorescence organic light emitting diodes (PHOLEDs) fabricated by soluble process. A soluble small molecule mixed host system consisting of hole transporting 4,4’,4’’ tris(N-carbazolyl)triphenylamine (TCTA) and bipolar carrier transporting 2,6-bis(3-(carbazol-9-yl)phenyl)pyridine (26DCzPPy) exhibits high solubility with smooth surface properties. Moreover, this small molecule host shows the smoothest morphological property similar to a vacuum deposited amorphous film. A low driving voltage of 5.4 V at 1000 cd/m² and maximum external quantum efficiency 14.6% obtained in the solution processed blue PHOLEDs are useful for large area low cost manufacturing.