Sorption of As(V) from aqueous solution using acid modified carbon black

The sorption performance of a modified carbon black was explored with respect to arsenic removal following batch equilibrium technique. Modification was accomplished by refluxing the commercial carbon black with an acid mixture comprising HNO(3) and H(2)SO(4). Modification resulted in the substantial changes to the inherent properties like surface chemistry and morphology of the commercial carbon black to explore its potential as sorbent. The suspension pH as well as the point of zero charge (pH(pzc)) of the material was found to be highly acidic. The material showed excellent sorption performance for the removal of arsenic from a synthetic aqueous solution. It removed approximately 93% arsenic from a 50mg/L solution at equilibration time. The modified carbon black is capable of removing arsenic in a relatively broad pH range of 3-6, invariably in the acidic region. Both pseudo-first-order and second-order kinetics were applied to search for the best fitted kinetic model to the sorption results. The sorption process is best described by the pseudo-second-order kinetic. It has also been found that intra-particle diffusion is the rate-controlling step for the initial phases of the reaction. Modelling of the equilibrium data with Freundlich and Langmuir isotherms revealed that the correlation coefficient is more satisfactory with the Langmuir model although Freundlich model predicted a good sorption process. The sorption performance has been found to be strongly dependent on the solution pH with a maximum display at pH of 5.0. The temperature has a positive effect on sorption increasing the extent of removal with temperature up to the optimum temperature. The sorption process has been found to be spontaneous and endothermic in nature, and proceeds with the increase in randomness at the solid-solution interface. The spent sorbent was desorbed with various acidic and basic extracting solutions with KOH demonstrating the best result ( approximately 85% desorption).     

Evaluation of gene index for identification of Byssochlamys spp

Comparative sequence analysis was performed on the 18S rRNA gene (1,676 bp), 26/28S rRNA gene D2 region (321 bp) and lys2 (997 bp) to evaluate the gene index for rapid, accurate and convenient identification of Byssochlamys spp. and related species. The results showed that 26 strains (11 species) of the clade could be identified or grouped by means of each gene sequence. The highest resolution to discriminate these species was observed with lys2, but 26/28S rRNA gene D2 region was considered to be the best index for convenient identification. In addition, phylogenetic analysis based on these genes indicated that genus Byssochlamys is not monophyletic, although species in the clade are closely related to each other. Re-classification will be necessary, based on detailed morphological observations.     

Third-order nonlinear optical properties of a π-conjugated biradical molecule investigated by third-harmonic generation spectroscopy

Third-order optical nonlinearity of a biradical molecule with open-shell π-electron system, 1,4-bis- (4,5-diphenylimidazole-2-ylidene)-cyclohexa-2,5-diene (BDPI-2Y) was investigated by the third-harmonic generation method. The figure of merit for third-order optical nonlinearity in BDPI-2Y is comparable to those for conjugated polymers, which have elongated closed π-conjugated systems. This indicates that the biradical nature of BDPI-2Y enhances third-order optical nonlinearity.     

Fiber-Optic 60-GHz Wireless Downlink Using Cross-Absorption Modulation in an EAM

We demonstrate the 60-GHz radio-over-fiber downlink adopting the fiber-optic upconversion process. The cross-absorption modulation (XAM) in the multiple-quantum-well electroabsorption modulator (MQW-EAM) is incorporated for the fiber-optic upconversion. Error-free transmission of the 1.25-Gb/s and 622.08-Mb/s pseudorandom bit sequence data is achieved without critical power penalties after the fiber transmission up to 34 km followed by 1-m wireless transmission between the base station and the customer unit. The system performance is dependent on the bias voltage asserted to the MQW-EAM due to the bias-dependent modulation characteristics of XAM and absorption changes. The optimum performance is obtained at the bias of -0.8 V.     

Ultraviolet generation tunable to 0.185 microm in CsLiB6O10

CsLiB(6) O(10) has been found to be phase matchable for type-1 sum frequency generation to a minimum of 0.185 mum by mixing the fifth harmonic of a Nd:YAG laser at 1.0642 mum and the output of a KTP parametric oscillator pumped by the second harmonic of the same Nd:YAG laser at 20.0 degrees C. The improved Sellmeier equations and the thermo-optic constants of this crystal are reported.     

Asynchronous, all-optical signal processing based on the self-frequency shift of a gigahertz Raman soliton

Ultrafast asynchronous all-optical signal processing is experimentally demonstrated. It is based on the intensity-dependent, self-frequency shift of a gigahertz Raman soliton. We demonstrate error-free, asynchronous, all-optical, bit-by-bit, self-signal recognition and demultiplexing from contended optical packets without use of an optical buffer, control pulse, or bit-phase synchronization. Fourfold, contended, 9.95-Gbit/s optical packets are transmitted through a conventional repeater span of 80 km and simultaneously demultiplexed to multiwavelength 9.95-Gbit/s optical packets with 0.5-dB processing sensitivity. Furthermore, we successfully accomplish demultiplexing from overlapping signals in contended optical packets with better than 3-dB recognition sensitivity. We confirm the capability of realizing a 3x cascade operation from bit-error-rate measurements.     

Integrated nuclear data utilisation system for innovative reactors

A five-year research and development project on an integrated nuclear data utilisation system was initiated in 2002, for developing innovative nuclear energy systems such as accelerator-driven systems. The integrated nuclear data utilisation system will be constructed as a modular code system, which consists of two sub-systems: the nuclear data search and plotting sub-system, and the nuclear data processing and utilisation sub-system. The system will be operated with a graphical user interface in order to enable easy utilisation through the Internet by both nuclear design engineers and nuclear data evaluators. This paper presents an overview of the integrated nuclear data utilisation system, describes the development of a prototype system to examine the operability of the user interface and discusses specifications of the two sub-systems.